Keryx 🏛️

Every time an AI uses a creator's work as a source, the creator gets paid — instantly.

🔗 Live: keryx.cc — free to try, no wallet, no sign-up  ·  ▶️ npm run demo — the whole loop, real settlement, ~90s  ·  🤖 npx -y keryx-mcp@latest — plug Keryx into any MCP agent  ·  🧩 Fork the Arc primitives

The problem

The web's economics assume a human reader: you write, people visit, attention becomes ads, subscriptions, tips. AI agents broke that contract. They read everything and send back nothing — no click, no view, no cent. Every answer an assistant gives is built on someone's work, and that someone is invisible at the exact moment their work proves its value.

Keryx (κῆρυξ — herald) exists to fix that one moment. It makes citation itself the payment event: the instant an agent relies on your writing to answer a question, you are paid, proportional to how much you helped, settled sub-cent in USDC on Arc. No accounts, no invoices, no ad tech. A creator onboards by pasting an RSS URL. An agent pays because paying is cheaper than not knowing.

Related MCP server: Tilde x402 MCP Server

What Keryx is

Keryx is a citation-toll reading agent — an autonomous reader with a wallet, and the payment rail underneath it. Give it a question and a budget:

1. It decomposes the question into sub-claims and discovers candidate sources (free previews).

2. It decides, per source: buy / skip / cache — expected value vs price vs remaining budget, with a human-readable rationale for every choice.

3. It pays the x402 toll only for what it buys, checks sufficiency after each read, and stops early when it has enough.

4. It synthesizes a grounded answer with inline citations, weighs each source's real contribution, and settles a weighted USDC nanopayment to every creator it cited — multi-author works split on-chain, 100% to creator wallets, 0% platform fee.

The result is a working micro-economy: readers that pay by default, and writers that earn by being useful — not by being clicked.

An agent that genuinely decides

Most "payment agents" are scripts with a wallet. Keryx's differentiator is visible agency — the model reasons about money and shows its work, streamed live to the UI:

• Buy / skip / cache with rationale — every spend decision is logged in plain language, per source.

• Adjudication ⚖️ — when two sources conflict, the agent doesn't average them; it decides which to trust and says why.

• Confidence verdict 📊 — it rates its own answer (High / Moderate / Low) and hedges the prose accordingly, instead of bluffing.

• Evidence ledger — every rewarded citation carries a claim-indexed exact quote. The orchestrator verifies that quote against content it actually read before the marker can receive a citation reward; rejected markers are removed from the answer.

• Cross-query memory — sources that proved useful (or useless) in past runs on the same subject shift future buy/skip decisions. A source is scored against the runs that actually read it, so a skip never becomes evidence against the source it skipped.

• Semantic discovery — candidate matching by embedding similarity, not keyword luck.

• Emergent frugality — it stops early, reuses its cache, and correctly spends nothing when nothing is worth buying.

Money safety is enforced in code, not by the model: the LLM proposes value; the orchestrator enforces the hard budget cap, so a hallucinated number can never overspend. An economic-invariant test suite (spend ≤ budget, payouts = weights, splits sum exactly) runs in CI on every push.

Example trace (real output):

[decide]  BUY Agent Economy Weekly — strong match on x402, autonomous, commerce; worth the $0.004 toll
[decide]  SKIP Garden & Soil Monthly — weak match (no key terms); not worth $0.002
[fetch]   Paid $0.004 to Agent Economy Weekly — S1
[sufficiency] Read 2 sources covering all sub-claims; stopping early to save budget
[settle]  Settled $0.015 → Mara Okoye · $0.010 → Devin Park   (60/40 author split)
📊 $0.032 spent → 100% to creators · 3 bought / 3 skipped

For creators

• Claim proven demand — keryx.cc/wanted shows claims paid dispatches left under-covered. Check your RSS feed, offer the exact matching post, and Keryx queues a bounded targeted retry after ownership verification. Fulfillment is public only when that source passes the evidence gate and its citation reward really settles. Every claim has a canonical shareable brief and social card, so the specific gap can reach the writer who covers it.

• Onboard from your own wallet — paste an RSS feed at keryx.cc/register and your wallet writes the source to the on-chain registry itself. Keryx sets up the x402-priced endpoint and the free preview; it never holds your key, and the faucet on that page covers the gas. All 20 listed sources are written to the on-chain registry, including real public feeds — Hugging Face, Vitalik Buterin, CoinDesk, the Ethereum Foundation, Stripe, Latent Space, Simon Willison — each earning per citation.

• Own your payout — the payout address is the wallet you signed in with. The first owner-verified creator (conzit.com) proved feed ownership, set its address, was cited & paid end-to-end — and has since claimed its registry record from its own wallet, so its on-chain creator is the creator, not Keryx. We've also proposed this as an opt-in convention upstream in RSSHub. Honest note: the demo sources seeded before this switch still have operator-held payout keys — they are Keryx's own sample publications, not third-party creators. Nine of the twenty on-chain records also name Keryx's treasury as their registry creator, so the treasury, not the source wallet, can update or deactivate those nine. The payout address is correct on all twenty — an hourly watchdog re-reads every record from the chain and publishes the comparison on /status.

• Know the moment you're cited — opt into a plain email alert (no webhook server needed, rate-capped, one-click unsubscribe) and/or signed webhooks that fire the instant a citation settles; every payout on your public earnings page shows the actual question your work helped answer.

• Show it off — an embeddable "Cited by Keryx" badge (live SVG at /api/creator/<id>/badge.svg) displays your real citation count + USDC earned on your own site, with copy-paste Markdown/HTML on each creator page. Payouts become portable, verifiable proof.

• Cash out yourself, gas-free — a self-serve, non-custodial withdraw: your wallet signs a Gateway burn intent in the browser, the treasury relays gas. Real creators have executed real on-chain cash-outs.

• Keep everything — 100% of every citation reward goes to creator wallets. 0% platform fee.

• Squat-proof identity — sources live in an on-chain SourceRegistry (0x2e12Fa…) with creator-scoped IDs and on-chain multi-author splits.

For developers & agents

• Free, no-wallet trial — keryx.cc answers without any setup, with a graceful upgrade path when you outgrow the free budget.

• Browser extension (extension/) — highlight text on any page and ask Keryx from a toolbar popup, or right-click to list a page you own as a paid source. A thin, no-key client over the OpenAI-compatible endpoint; load unpacked on any Chromium browser.

• Remote MCP — connect an MCP client directly to https://keryx.cc/mcp over Streamable HTTP: no package or local wallet process. The research tool has an anonymous, IP-limited trial; an ask-scoped kx_live_… Bearer key raises the cap and attributes usage to its verified wallet. Creator rewards still settle in USDC on Arc. Quick connect: codex mcp add keryx --url "https://keryx.cc/mcp?client=codex" or claude mcp add --transport http keryx "https://keryx.cc/mcp?client=claude". The interactive setup guide is at /integrations/mcp.

• Local x402 MCP — on the official MCP registry; npx -y keryx-mcp@latest keeps the caller-funded path: its local Arc wallet pays Keryx's x402 toll before Keryx researches and pays creators.

• Discord slash command — install the Keryx app in any server and type /ask: the reply embed carries the grounded answer, every creator paid, and a link to the dispatch trace. No bot process — signed interactions POST straight to the API (docs/discord-bot-setup.md).

• Telegram bot — DM @keryxai_bot any question (or /ask … in a group): same full reasoning loop, same real creator payouts, answered in-chat with a dispatch-trace link. Webhook-only, no polling process (docs/telegram-bot-setup.md).

• Slack slash command — a /keryx … command for any workspace: signed requests POST straight to /api/slack/commands, the same full reasoning loop and real creator payouts answered in-channel with a dispatch-trace link. No bot token or scopes — replies ride the command's response_url. Setup + app manifest in (docs/slack-bot-setup.md).

• Agent-to-agent API — POST /api/agent/ask lets other agents buy Keryx's research over x402: an agent paying an agent that pays creators, end to end.

• OpenAI-compatible endpoint — point any OpenAI SDK or tool (LangChain, LlamaIndex, OpenWebUI, LibreChat, Continue) at https://keryx.cc/api/v1 with model keryx: a drop-in Chat Completions API. Free with no key, or pass a kx_live_… key as the Bearer token for higher limits. Every cited creator is still paid downstream in USDC on Arc; with stream:true, the agent's live buy/skip/trust reasoning streams as reasoning_content deltas. Try it with no install in the browser playground — it also hands you the exact curl/Python/JS call.

• Public API with wallet-issued keys — SIWE-authenticated key minting (hashed, show-once, rate-limited) and OpenAPI docs at /api/docs.

• Non-custodial by design — interactive spend uses a session EOA the user funds from their own wallet; the browser co-signs each x402 authorization in-tab. The funded amount is the hard cap. Keryx never holds your key or your funds.

• The chain decides who gets paid — before anything signs or settles, every payee is checked against the on-chain SourceRegistry, not against Keryx's database. Editing the database cannot reroute a single citation reward, on any path — browser, volume engine, or A2A.

• Transparent treasury — /api/treasury publishes the settlement wallet's chain-abstracted Gateway balance (via Circle App Kit), so anyone can audit what backs the payouts.

• Live activity feed — /api/activity streams the most recent real settled citations (source, question, reward) — a proof-of-life surface and a zero-prior-knowledge way for tooling to see what Keryx is citing right now; it also drives the live ticker on the landing.

• Answer archive as an Atom feed — subscribe to /answers/feed.xml and see every new paid answer as it settles. Keryx onboards creators by reading their RSS feeds; this is the same door pointed the other way — Keryx itself becomes a source any reader or agent can follow.

The money rails

Payments are the product, so none of them are pretend. Policy: no mocked settlement — every reported figure is a real, settled transaction; offline dev runs are loudly labeled SIMULATED.

• x402 pay-per-request (@circle-fin/x402-batching) — a two-toll design: a small fixed access toll to read, plus a dynamic citation reward priced by contribution weight. Fetched but uncited earns the toll; cited earns proportionally more only after its evidence passes the deterministic grounding gate.

• Circle Gateway nanopayments — batched sub-cent settlement (floor $0.000001). Average Keryx payment: ~$0.0044 — a true nanopayment, uneconomical on any card rail.

• Circle App Kit (Unified Balance Kit) — chain-abstracted treasury balance, published live on /status and /api/treasury.

• SourceRegistry contract on Arc — source identity, IPFS CIDs, multi-author splits; on-chain events drive the off-chain indexer.

• Encrypted content on IPFS — AES-256-GCM ciphertext pinned publicly; plaintext is released only after x402 settlement verifies. Free previews stay plaintext.

• USDC-native chain — Arc settles in <500ms with USDC as gas, which is what makes per-citation economics physically possible.

Live numbers

Arc testnet · snapshot 2026-07-23 · always current at /status

Top earners: Onchain Micropayments Digest $6.15 · Agent Economy Weekly $5.38 · Stablecoin Ledger $5.17 · Ethereum Foundation $0.86 · Latent.Space $0.67 · CoinDesk $0.66 · Stripe Blog $0.66 · Cointelegraph $0.65 · Hugging Face $0.52 · Vitalik Buterin $0.46 · Simon Willison $0.43 · Conzit Labs $0.07 (owner-verified).

Honesty on usage: most of this volume is generated by Keryx's own 24/7 autonomous agents (volume engine + headless web/A2A clients) — real on-chain settlement, agent-driven rather than external human traffic, and labeled as such on the dashboard. The external on-ramps (MCP server, A2A endpoint, owner-verified creators) are live; growing genuine third-party usage is the current push. Settlements batch through Circle Gateway, so on-chain proof is the batched settlement wallet + the SourceRegistry contract on arcscan, not per-payment tx links.

Architecture

BROWSER (Web App)                    IPFS + Arc Smart Contracts              Circle Gateway + Arc Testnet
─────────────────                    ─────────────────────────               ──────────────────────────────
┌──────────────────┐                 [SourceRegistry]
│ /ask page        │ (SIWE           on Arc 0x2e12Fa...                       USDC on Arc
│ + wallet connect │  auth)           • sources[]                             (ERC-20, 6 decimals)
│                  │                   • emit Registry events
└────────┬─────────┘                   • indexed by off-chain DB
         │ session-grant
         │ (user funds session EOA)     [IPFS Content]
         │ MetaMask tx → session       • AES-256-GCM encrypted                [Circle Gateway]
         │ deposits in Gateway          • plaintext released only post-settle  • batch settlement
         │                                                                      • x402 EIP-712 verify
         │                             [Keryx API]
         │ co-sign loop (fetch+POST):  • auth: SIWE JWT (browser + API key)   [Arc RPC]
    /api/ask (SSE) ──────────────────▶ /api/session/*   (grant, credit)       rpc.testnet.arc.network
    browser streams                     /api/ask         (agent asks, gets
    sign-requests                       /api/ask/sign    sign-requests back)
    ◀────────────────────────────────  /api/source/[id] (fetch toll + IPFS key)
    client-side session key             /api/cite        (citation reward)
    signs EIP-712                       /api/keys        (API key mint/verify)
    auto-signs (NO prompt)              /api/agent/ask   (A2A, x402-priced)
                                        /api/treasury    (App Kit unified balance)
                                        /api/docs        (OpenAPI)

    Agent brain (lib/agent/run-agent.ts):
    decompose→discover→decide→fetch→sufficiency→synthesize→attribute→settle

Run it

One command — the full cycle (~90s). Decide → pay the x402 toll → read → synthesize → settle weighted citation rewards, then print the Arc-testnet wallets whose USDC actually moved:

npm run demo -- "How do x402 and stablecoins enable AI agent commerce?" --budget 0.05

With ANTHROPIC_API_KEY + AGENT_FUNDER_PRIVATE_KEY + NEXT_PUBLIC_KERYX_REGISTRY_ADDRESS it settles for real and prints on-chain proof; without them the same flow runs offline, clearly labeled SIMULATED — a mock is never presented as settled.

# 1. Install (Node v20.18.2+)
npm install

# 2. Configure (optional — runs offline with zero keys)
cp .env.example .env.local

# 3. Wallets + demo sources
npm run generate-wallets
npm run seed-sources

# 4a. One question, full reasoning trace in the terminal
npm run ask -- "How do x402 and stablecoins enable autonomous AI agent commerce?" --budget 0.05

# 4b. Or the full web app (SIWE auth, session grants, browser co-sign)
npm run dev          # http://localhost:3939

# 5. Autonomous volume engine · live metrics
npm run seed -- --count 20
npm run metrics

Built to stay up

Keryx runs as a real service, not a demo that dies after the video:

• Public /status + /api/health — uptime, deployed commit, settlement mode, live traction, treasury balance.

• Low-downtime deploys — new builds compile beside the live one, swap atomically, health-gate, and auto-roll-back if the new build doesn't come up (npm run redeploy).

• Treasury watchdog — hourly cron checks settlement-wallet USDC + gas against thresholds and alerts before settlements can stall; failed settlements alert immediately.

• Rotating off-box backups of the traction datastore, hourly.

• CI — typecheck + the economic-invariant suite on every push.

• 24/7 volume daemon — the agent keeps reading, paying, and settling around the clock.

Security & honest trade-offs

The interactive path is non-custodial, with the remaining testnet trade-offs documented (each with an upgrade path in the roadmap):

1. Circle facilitator — x402 settlement batches through Circle's facilitator (no on-chain alternative on Arc testnet yet).

2. Server holds the IPFS decryption key — content is encrypted at rest, but key release is server-side (Lit Protocol planned once Arc is supported).

3. Session key lives in a Web Worker — derived there, never returned; the tab holds only AES-GCM ciphertext under a non-extractable key. The worker signs payment authorizations to registry-authorised payees only, and transactions only to USDC/Gateway — so page-level XSS can neither steal the key nor name itself as payee. Residual: the derivation signature is produced on the main thread, a one-call window at setup.

4. Treasury gas wallet — holds gas only, rotated; a compromise cannot touch creator funds.

Full threat matrix and verification results: docs/security-threat-model.md.

Fork the primitives

The reusable building blocks are MIT-licensed and standalone in keryx-arc-primitives (also vendored at arc-primitives/ — clone with --recurse-submodules):

• Two-toll x402 settlement — fixed access price + dynamic citation reward.

• On-chain creator/attribution registry — squat-proof IDs, multi-author splits, event indexer.

• Non-custodial spend cap — server-enforced budget over a user-funded session EOA.

Project docs

• docs/openai-compatible-api.md — drop-in recipes for OpenAI SDK, LangChain, LlamaIndex, Open WebUI, LibreChat, Continue

• docs/system-architecture.md — data/money flow + on-chain components

• docs/security-threat-model.md — threat matrix, audits, residuals

• docs/codebase-summary.md — module map

• docs/project-roadmap.md — where this is going

• TRACTION.md — real payment volume, updated from the live datastore

• FEEDBACK.md — Circle/Arc dev-tool feedback we filed while building

• DECISIONS.md — architecture decision log

• CLAUDE.md — contributor orientation

Origin & where it's going

Keryx started at the Lepton Agents Hackathon (Canteen × Circle, on Arc, June 2026) as the canonical build of the "herald" model — content cited, paid per citation — and never stopped running. It has been live at keryx.cc since, settling real value every hour, onboarding real feeds, and shipping continuously in public. Next: Lit Protocol for client-side IPFS key release, growing external agent traffic through the MCP and A2A on-ramps, and a single config flag between this system and mainnet.

Stack

Next.js 16 · React 19 · Tailwind 4 · shadcn/ui · viem/wagmi · @circle-fin/x402-batching · @circle-fin/unified-balance-kit · @x402/fetch · Node node:sqlite / Supabase · Anthropic / DeepSeek. Built on the verified circlefin/arc-nanopayments x402/Gateway plumbing.