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x402 rails / x402 v2

x402 v2 on BlockRun: the manifest, the networks, the headers

BlockRun publishes an x402 v2 manifest listing every payable endpoint with its price and CAIP-2 network, next to the v1 list and an OpenAPI document with an x402 scheme.

Get your agent on BlockRun Read the docs

How it works

x402 is the HTTP payment protocol: a paid endpoint answers a request without payment with a 402 and the requirements, the client signs a USDC authorization and retries. The v2 conventions add a machine-readable manifest of endpoints with prices and CAIP-2 network ids, so an agent can decide what it can afford before it calls.

BlockRun's manifest at /.well-known/x402 carries both the v1 resource list and the v2 endpoints array, derived from the same OpenAPI document the API is described by, so the three cannot disagree on a price. The OpenAPI document declares the x402 security scheme on every paid operation and marks free ones explicitly.

Behind it is the BlockRun catalog: 78 chat models plus image, video, music and speech generation, search, market data and multi-chain RPC, priced per call. 6 open-weight models are free and need no wallet.

Setup

1. Read the manifest

curl https://blockrun.ai/.well-known/x402 | jq '.endpoints[:3]'

2. Read the OpenAPI security scheme

curl https://blockrun.ai/openapi.json | jq '.components.securitySchemes'

Questions

Do v1 clients still work?
Yes. The manifest keeps the v1 resource list and the 402 flow is unchanged.
Where do the prices in the manifest come from?
From the OpenAPI document, at render. The 402 is always the authoritative quote for a specific call.

Related

Two ways to run this

Get an API key

Sign in, get a key, and call the same endpoints with usage billed to your account. For teams that want one invoice instead of one wallet.

Get an API key 

Or let your agent pay per call, in USDC

No account, no API key. Three steps, and the last one is the request this page is about.

  1. 01
    Point your agent at BlockRun

    Install ClawRouter, or add the BlockRun MCP server to Claude Code, Cursor, Codex or OpenClaw. Any OpenAI-compatible client works too — change the base URL, nothing else.

    curl -fsSL https://blockrun.ai/ClawRouter-update | bash
  2. 02
    Fund a wallet with USDC

    Send USDC to a wallet on Base or Solana. There is no account to create and no API key to issue: the wallet is the account, and it pays per call.

  3. 03
    Use BlockRun from x402 v2

    The first call returns HTTP 402 with the exact price, your agent signs it, and the answer comes back. Payment settles on-chain; nothing is charged if the call fails.

    curl https://blockrun.ai/.well-known/x402 | jq '.endpoints[:3]'
ClawRouter setup →How paying per call works →

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