Rail402

x402 payments infrastructure for Stellar: a facilitator, a discovery layer (Bazaar), an MCP server for agents, a payments explorer, and the SDKs to build on all of it.

Live facilitator (testnet): https://facilitator.rail402.dev

What's here

Directory	What it is
`apps/facilitator`	x402 verify / settle / supported service for `stellar:testnet`, with sponsored fees and the Bazaar co-deployed
`apps/bazaar`	catalog, automatic cataloging at verify/settle, `/discovery/resources` and `/discovery/search` (hybrid BM25 + embedding ranking)
`apps/mcp-discovery`	MCP server exposing search and a spend-capped paid-call tool
`apps/explorer`	indexes and classifies x402 settlements from the Stellar ledger, serves a public read API
`apps/cli`	command-line wallet and agent tool (`rail402`)
`apps/playground`	interactive demo of the discover → pay loop
`apps/docs`	documentation site
`packages/*`	error registry, seller/agent helpers, the `upto` scheme, conformance harness, canaries, umbrella SDK
`contracts/`	Soroban contracts: `upto` settlement and an agent spending policy
`examples/`	end-to-end integrations: paid API + agent, MCP tool seller, smart-account buyer

Payment schemes: exact and upto (authorize a ceiling, settle actual usage — backed by a small Soroban contract). Buyers can be classic keypairs or smart accounts; network fees are sponsored so buyers need no XLM.

Run it

pnpm install
pnpm --filter @rail402.dev/facilitator dev   # needs a funded testnet secret, see apps/facilitator/.env.example

Or with Docker (facilitator + Bazaar in one image):

docker build -t rail402 . && docker run -p 8080:8080 --env-file .env rail402

Checks

pnpm verify   # lint + typecheck + tests + dependency license gate
pnpm test

Settlement evidence (transaction hashes, conformance runs, rejection audits) is generated into docs/status/.

Packages

Published under the @rail402.dev scope on npm.

License

Apache-2.0. See LICENSE and NOTICE.

rail402 MCP Discovery