dev.rfc

Look up an IETF RFC by number. Pass number as RFC2616, 2616, or the integer 2616. Returns the RFC title, authors, publication date, status (e.g. INTERNET STANDARD, PROPOSED STANDARD, DRAFT STANDARD, INFORMATIONAL, EXPERIMENTAL, HISTORIC, BEST CURRENT PRACTICE), stream (IETF/IAB/IRTF/Independent/Legacy), DOI, canonical rfc-editor.org URL, and the full standards relationship chain: which RFCs this one obsoletes / is obsoleted by, and which it updates / is updated by. Authoritative data from the IETF/RFC Editor index. Use this to resolve whether a spec is current or superseded before relying on it.

price

$0.0012 USDC per call

method

GET/api/dev/rfc

payment

x402 v2 · USDC on Base (EIP-3009) or Solana (SPL transfer)

auth

None. Sign the payment, retry with PAYMENT-SIGNATURE.

tier

Tier 0 — no paid upstream

Parameters

Name	Type	Description
`number`required	string	RFC number, e.g. RFC2616 or 2616. min 1 chars · max 12 chars

Code samples

cURLbash

# 1. Probe with no auth → 402 envelope with PaymentRequirements
curl -sS 'https://2s.io/api/dev/rfc?number=example'

# 2. Sign + retry with PAYMENT-SIGNATURE:
curl -sS 'https://2s.io/api/dev/rfc?number=example' \
  -H 'PAYMENT-SIGNATURE: <base64-json-payload>'

# Or use the canonical runner (handles probe → sign → retry):
#   EVM_PRIVATE_KEY=0x... node --env-file=.env.local \
#     --experimental-strip-types scripts/x402-pay.ts \
#     'https://2s.io/api/dev/rfc?number=example'

TypeScript / Node — @2sio/sdktypescript

import { TwoS } from '@2sio/sdk'

const client = new TwoS({
  privateKey: process.env.EVM_PRIVATE_KEY as `0x${string}`,
})

const result = await client.dev.rfc({
  "number": "example"
})

console.log('endpoint:', result.endpoint)
console.log('cost:', result.costUsd, 'USDC')
console.log('tx:', result.settlement?.txHash)
console.log('data:', result.data)

Python — 2siopython

import os
from twosio import TwoS

client = TwoS(private_key=os.environ["EVM_PRIVATE_KEY"])

result = client.dev.rfc(number="example")

print("endpoint:", result.endpoint)
print("cost:", result.cost_usd, "USDC")
print("tx:", (result.settlement or {}).get("tx_hash"))
print("data:", result.data)

MCP — Claude Desktop / AgentKit / any MCP hostjson

// 1. Add @2sio/mcp to your MCP host config (Claude Desktop example below).
//    EVM_PRIVATE_KEY funds x402 payments per call.

// claude_desktop_config.json
{
  "mcpServers": {
    "2sio": {
      "command": "npx",
      "args": ["-y", "@2sio/mcp"],
      "env": { "EVM_PRIVATE_KEY": "0x..." }
    }
  }
}

// 2. Once the server is running, agents call this tool via standard MCP:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "dev.rfc",
    "arguments": {
      "number": "example"
    }
  }
}

Response

Field	Type	Description
`query`	object
`returned`	number
`rfc`	object
`source`	object

Example response datajson

{
  "query": {
    "number": 1
  },
  "returned": 1,
  "rfc": {
    "number": 1,
    "title": "example",
    "authors": [
      "example"
    ],
    "date": "example",
    "status": "example",
    "stream": "example",
    "obsoletes": [
      1
    ],
    "obsoletedBy": [
      1
    ],
    "updates": [
      1
    ],
    "updatedBy": [
      1
    ],
    "doi": "example",
    "url": "example"
  },
  "source": {
    "provider": "example",
    "url": "example",
    "license": "example"
  }
}

Discovery

/api/directory — full catalog of every endpoint
/openapi.json — OpenAPI 3.1 spec (per-op x-payment-info, x402Payment security)
/.well-known/x402 — machine-readable service descriptor for x402-aware crawlers
/.well-known/mcp/server-card.json — MCP SEP-1649 server card
/llms.txt — plain-text manifest for LLM ingestion

2s.io is x402-native. Every call is paid per-request from a USDC-funded EVM wallet on Base — no signup, no API keys, no monthly fees. Source code: github.com/2s-io/sdk.