Synthex Forge — x402 Paid Agent Services

Attested Agent Execution — bounded agent run (PAID $1.00)

VALUE: One audited agent execution with a cost ledger and a signed result, so the work is reproducible and the spend is attributable.

PRICE: $1.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Ebook Download

VALUE: The full 121-page book 'x402 — The Agent Economy' — the definitive account of building machine-native services agents pay for, in one file.

PRICE: $29.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Mint a signed typed receipt for any transaction or action.

VALUE: A signed receipt for an action, mintable as evidence of what happened — a portable 'it did that'.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Assess and attest a financial statement or metrics payload into signed, reproducible evidence.

VALUE: Signed, dated financial evidence extracted from a statement — the figure a lender, investor or auditor can rely on without a call.

PRICE: $0.35 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed self-contained audit evidence package with a Merkle root (PAID $4.00)

VALUE: A single signed package binding artifacts, assertions and attestations for a period — what an auditor asks for, without three weeks of chasing.

PRICE: $4.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Budget Preflight

VALUE: Whether this call fits the budget, BEFORE you spend — turns a surprise overage into a decision you can make in advance.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

x402 Bureau — full conformance audit of any endpoint (PAID $0.25)

VALUE: A full conformance audit of any target endpoint against the x402 standard, every clause, signed and dated — the check a buyer cannot do from the outside.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

x402 Bureau — conformance-check any issuer's receipt/offer (PAID $0.05)

VALUE: Independent verification that a receipt is genuine and matches the offer it claims to settle — counterparty-side proof, not your own.

PRICE: $0.05 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

x402 Bureau — reputation from signed observation history (PAID $0.10)

VALUE: The Verification Bureau's standing reputation read for a subject, from its own corpus — third-party standing you cannot manufacture.

PRICE: $0.10 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Compliance Check

VALUE: A specific, dated compliance verdict for one described processing activity — the artifact a regulator asks for, not a policy PDF.

PRICE: $1.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Containment Register

VALUE: A registered, signed containment policy with named emergency contacts — so 'what happens if this agent goes wrong' has an answer that is already signed and enforceable.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed rule-based extraction of the clauses that decide money and liability (PAID $1.50)

VALUE: The obligations in a contract as structured, dated data — so compliance is a query, not a re-read of forty pages.

PRICE: $1.50 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Counterparty credit & conduct score from your own observations (PAID $0.50)

VALUE: Price the risk of paying an unknown agent, endpoint or host from YOUR OWN observations — a 0-1000 credit and conduct score with the weighted factors behind it, so you price trust before you pay.

PRICE: $0.50 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Issue a scoped, expiring, offline-verifiable capability credential (PAID $0.05)

VALUE: A scoped, time-limited, signed credential — delegation with an expiry, so access does not have to be revoked by hand.

PRICE: $0.05 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

C2Pa Verify

VALUE: Whether a media file carries a valid C2PA provenance manifest — the check that separates authentic media from generated media.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Assess whether data is still fresh, undated or conflicting (PAID $0.02)

VALUE: Whether a claim's source is still fresh enough for the decision you are about to make — staleness is the failure mode nobody prices in.

PRICE: $0.02 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed Snapshot

VALUE: A tamper-evident snapshot of a series with its sources and fetch time — a data point you can defend later, not just cite.

PRICE: $0.30 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Validate, normalise and mechanically repair a payload against a declared JSON-Schema subset. Repair never fabricates data: a required property with no default is reported missing, not inserted. Keywords outside the supported subset are reported in schema_keys_unsupported rather than silently ignored.

VALUE: Coercion and repair of a payload against a schema, with the repairs itemised — malformed input becomes clean input, and every change is on the record.

PRICE: $0.02 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed decision attestation with an assurance level and explicit unknowns (PAID $2.50)

VALUE: A signed, dated, replayable attestation of a decision and the policy that produced it — the difference between a decision and an accountable one.

PRICE: $2.50 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed advisory dispute ruling from a deterministic rubric (PAID $2.00)

VALUE: A binding ruling on a dispute from the contract, evidence and policy — so the resolution is a signed artifact, not an argument.

PRICE: $2.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Prior-test registry query: what has actually been tested on an instrument/timeframe/strategy-type before, and what the prior evidence says. Every field is optional but at least one must be supplied.

VALUE: What has actually been tested on this instrument, timeframe and strategy type before, and what the prior evidence says — so you do not pay to rediscover a known result.

PRICE: $0.05 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Is that track record real, or did you find it by looking? (PAID $3.00)

VALUE: Whether a claimed edge survives replication on your own returns — the test that separates a real edge from a curve fit.

PRICE: $3.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Exact-decimal financial calculation with its published convention (PAID $0.01)

VALUE: Exact decimal arithmetic under stated conventions — financial totals that do not drift by a cent when you scale them.

PRICE: $0.01 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Seal one signed-attribution / forensics evidence record into a tamper-evident vault entry.

VALUE: Sealing one evidence record into a tamper-evident vault entry — chain of custody that survives after the fact.

PRICE: $0.20 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Bind sealed forensics-vault entries into ONE signed query receipt.

VALUE: Querying that vault by actor or predicate — the retrieval side of evidence you cannot quietly edit.

PRICE: $0.15 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Agent Spend Governor — ATOMIC reserved lease (PAID $0.02)

VALUE: A leased, expiring reservation of budget for a named intent — spend that is committed before it is spent.

PRICE: $0.02 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Agent Spend Governor — settle a lease, idempotent (PAID $0.02)

VALUE: Closing a reservation against what was actually spent — the difference between a budget and a wish.

PRICE: $0.02 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Liveness and settlement-configuration probe for the x402 service. Returns the live network, receive address and whether settlement is enabled.

VALUE: Free, because an agent that cannot tell a live service from a dead one pays for nothing useful.

PRICE: FREE — no payment required.

Call it directly. No payment, no headers, no account.

Identity Control Proof

VALUE: Proof that a claimer controls an identifier, signed and dated — so an identity claim is a verification, not an assertion.

PRICE: $0.20 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

The signed Synthex Agentic-Commerce Index: a dated, rule-published mark (PAID $5.00)

VALUE: The Synthex Agentic-Commerce Index — a dated, signed mark on the agentic economy itself, computed from our own observation corpus of x402 settlements. The rules are published with the answer, so you can re-derive the marks.

PRICE: $5.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Invoice Ocr

VALUE: Structured line items, vendor and total from an invoice image — the manual data entry an agent removes.

PRICE: $0.02 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Licence Check

VALUE: Whether a specific dataset licence permits a specific intended use in a specific jurisdiction — a legal question with a dated answer.

PRICE: $0.10 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed compliance certificate: does this portfolio comply with this mandate (PAID $5.00)

VALUE: A signed, dated compliance certificate an allocator can actually file — replaces an analyst hour on a document, and never certifies compliance on missing evidence.

PRICE: $5.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed market-hours / holiday / settlement answer (PAID $0.01)

VALUE: Session hours, holidays and settlement cut-offs for a venue, DST aware — so you never settle into a closed market.

PRICE: $0.01 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed bar series over an explicit range (PAID $1.00)

VALUE: Historical bars for an instrument, formatted and bounded — the data a backtest needs, without hand-assembling it.

PRICE: $1.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed bulk bar series, up to 20 pairs (PAID $5.00)

VALUE: The same history for many pairs in one call — the cost of a portfolio-wide study drops to a single request.

PRICE: $5.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed OHLCV snapshot from our own market-data store (PAID $0.01)

VALUE: A point-in-time market snapshot for an instrument, bounded and timestamped — the 'now' you stamp a decision with.

PRICE: $0.01 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Judge Grade

VALUE: A rubric-scored judgement of a model response, signed and dated — evaluation you can re-check rather than re-argue.

PRICE: $0.15 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Tool Permission Threatmodel

VALUE: A threat model of a tool manifest with per-tool permissions and runaway protection — the analysis before you grant an agent a capability.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Uptime Canary Probe

VALUE: Independent uptime confirmation tied to a settled receipt — proof of service that a self-report cannot manufacture.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Return the latest signed, reproducible sealed state for a key.

VALUE: Reading that durable memory back — continuity for an agent that must not forget.

PRICE: $0.05 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Persist a budget-capped state version into a signed, reproducible memory vault.

VALUE: A durable, owned memory entry — a fact that survives the session and belongs to someone you can name.

PRICE: $0.10 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed NAV attestation for agent treasuries: what is this book worth, as of when, computed how (PAID $10.00)

VALUE: A signed NAV attestation for agent treasuries — the single document every allocator, auditor and counterparty asks for: what is this book actually worth, as of when, computed how.

PRICE: $10.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Output Verify

VALUE: Whether an output actually satisfies its schema, claims and staleness budget — a check the model cannot run on itself.

PRICE: $0.50 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Pass Purchase

VALUE: Prepaid capacity at a lower effective per-call price — the difference between renting and owning the cost.

PRICE: $25.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Buy a trial prepaid capacity pass — $0.50 for 20 calls, 7 days (PAID $0.50)

VALUE: The trial tier of the same prepaid capacity — proof of the unit economics before you commit to the full pass.

PRICE: $0.50 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Validate a captured x402 402 payment envelope (PAID $0.25)

VALUE: Whether a signed payment envelope is well-formed, unexpired and for the right resource — catch a bad payment before it settles.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Deterministic policy evaluation: is this action allowed under this policy given this caller state? Returns a signed allow/deny verdict with the specific rule that fired. Safe-deny on malformed input.

VALUE: Whether one action is permitted for one caller under one policy, as of one instant — enforcement you can ask a question of.

PRICE: $0.10 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed exposure report under the caller's own risk model (PAID $3.00)

VALUE: Risk for a set of positions under a named model, dated — the number that decides whether a portfolio is sized right.

PRICE: $3.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed preflight verdict on a counterparty BEFORE you pay them. Returns a three-state verdict (go | caution | avoid | unknown) with dated, signed evidence. Fewer than 3 independent observations in 30 days returns unknown with the coverage gap named — never a guessed go.

VALUE: The agent's first call: a signed three-state verdict on a counterparty before you pay them, with the coverage gap named when there isn't enough evidence.

PRICE: $0.01 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Pre-trade risk gate: approve / reduce / reject an order against your own declared limits (PAID $0.25)

VALUE: The order gate: approve, reduce or reject an order against the risk limits you declared — and a reduce hands back a size that actually passes, so one bad order never reaches the market.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed quota reservation decision (PAID $0.01)

VALUE: Whether a call fits a remaining quota, before you spend it — the check that stops a quota from being discovered by exhaustion.

PRICE: $0.01 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed reference rates, always as-of stamped. FX leg is the ECB euro reference rates (official, daily); crypto leg is the Binance public spot bookTicker. On a weekend or holiday the LAST BUSINESS DAY is returned with is_stale=true and the real staleness in seconds — a stale rate is never presented as live.

VALUE: What is this amount worth right now?

PRICE: $0.01 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Readiness Attest

VALUE: A signed readiness attestation with the evidence and policy snapshot behind it — readiness you can evidence, not assert.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Compute a signed agent-reputation composite from an agent id and its event list.

VALUE: Reputation scored from dated, signed behaviour events rather than self-reported claims — so you can price trust before you trade.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Sec Extract

VALUE: Structured data extracted from a company's SEC filings — primary filings, not a data vendor's interpretation of them.

PRICE: $0.05 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Dependency Risk

VALUE: Risk analysis of a dependency set for a given ecosystem — supply chain exposure enumerated rather than assumed.

PRICE: $0.20 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Redteam Authorized Scan

VALUE: An authorized adversarial scan of a target you have evidence of permission to test — the finding, with the authorization on the record.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Threatmodel Analyze

VALUE: A threat model of a tool manifest in its deployment context — attack surface before it is exploited.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed conditional-release verdict — are the release conditions met? (PAID $0.25)

VALUE: A settlement that releases only if its named conditions hold — escrow logic as a single call.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed settlement-receipt verdict for a tx hash (PAID $0.01)

VALUE: Independent confirmation that a transaction settled to the right payee for the right amount — proof of payment from the ledger, not from the payer.

PRICE: $0.01 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Create a signed, tamper-evident track-record attestation (Ed25519 + SHA-256) over any claim.

VALUE: A signed, dated attestation of a claim with a claim type — a standalone 'this is true, and here is when'.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Generate a tamper-evident, signed research brief on a requested topic.

VALUE: A researched brief on a topic with its sources and depth stated, attested — research with a provenance you can point at.

PRICE: $2.00 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Signed Research

VALUE: Paid route: $0.50 USDC on eip155:8453 (USD). An unauthenticated request is answered HTTP 402 with a machine-readable price challenge in the Payment-Required response header and a JSON body carrying error, error_reason, error_message and x402Version. Error codes and their remedies are published at https://x402.synthexforge.com/v1/errors.

PRICE: $0.50 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Screen an SME sale against the house LBO structure and rules (PAID $2.50)

VALUE: A structured screen of an SME on turnover, EBITDA, structure and sector — the first pass over an acquisition candidate.

PRICE: $2.50 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Multi-channel social-signal search (PAID $0.02)

VALUE: Paid route: $0.02 USDC on eip155:8453 (USD). An unauthenticated request is answered HTTP 402 with a machine-readable price challenge in the Payment-Required response header and a JSON body carrying error, error_reason, error_message and x402Version. Error codes and their remedies are published at https://x402.synthexforge.com/v1/errors.

PRICE: $0.02 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Fold research + quant + audit inputs into ONE signed verdict.

VALUE: A signed verdict fusing audit, quant and research inputs on one subject — the answer, with the inputs that produced it.

PRICE: $0.50 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Compute a signed trusted-route ranking for a counterparty.

VALUE: The specific routes an agent is cleared to call, with the evidence behind each clearance — so you can enforce a least-privilege allowlist instead of trusting a name.

PRICE: $0.30 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Utils Code Review Brief

VALUE: A structured review brief for a code block — the issues worth reading, separated from the noise.

PRICE: $0.15 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Utils Doc Convert

VALUE: Converting a document between formats with a signed output — turning a file into something a machine can read.

PRICE: $0.10 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Utils Invoice Extract

VALUE: Structured line items from invoice text — the manual data entry an agent removes, without the image.

PRICE: $0.10 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Utils Pii Redact

VALUE: Redacting names and other identifiers from text, in place — compliance with a diff you can inspect.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Utils Schema Cleanup

VALUE: Cleaning a CSV or JSON payload against a schema — the messiness removed before it reaches your model.

PRICE: $0.05 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Utils Translate Doc

VALUE: Translating a document with its structure preserved — a document an agent in another language can actually use.

PRICE: $0.10 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Register a service into the network-effect verify catalog and grow the trust index.

VALUE: Registering a service in the verification catalogue with its signature — the entry that lets others verify it too.

PRICE: $0.25 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

Verify a signed receipt you already hold — FREE, no payment, no network call to us. Recomputes the canonical JSON digest and checks the Ed25519 signature against the published public key, so you can confirm a receipt's authenticity before you act on it.

VALUE: Free, because verifying a receipt you already paid for must never cost a second payment.

PRICE: FREE — no payment required.

Call it directly. No payment, no headers, no account.

Dated proof of what existed at time T (PAID $0.01)

VALUE: A dated economic anchor point for the x402 economy — the yardstick for whether activity is actually growing.

PRICE: $0.01 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.

The queryable index of the agent economy: what is offered, what it costs, and whether it still works. An endpoint is never invented — every result exists in the corpus with a last_seen.

VALUE: The live index of paid x402 services, filterable by price, network and conformance — where new services are found.

PRICE: $0.02 USDC per call.

HOW TO PAY: USDC on eip155:8453, exact scheme, to 0xc8fF67FAE72596478599EAAcfad8656fAe1113c8. Sign an EIP-3009 transferWithAuthorization for the exact amount and put it in the X-PAYMENT header, then retry the same call. An unpaid call returns a payment_required payload with the amount, asset, network and payTo already filled in. The synthex-x402 SDK (PyPI and npm) does the 402 -> sign -> retry loop in one call.