law.cfr-section

Fetch the authoritative text of any section of the US Code of Federal Regulations by title and section number — for example title 12, section 1026.43 returns Regulation Z’s ability-to-repay standards. Returns the canonical citation, section heading, full plain text, Federal Register source credit, the as-of date, and a link to the official eCFR page. An optional date parameter (YYYY-MM-DD) retrieves the historical text in force on that date, back to 2017. Data from the Electronic Code of Federal Regulations (US GPO / Office of the Federal Register), public domain, updated daily — verify regulatory citations against the authoritative source instead of relying on model memory.

price

$0.0018 USDC per call

method

GET/api/law/cfr-section

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
`title`required	integer	CFR title number, 1-50 (e.g. 12 for Banks and Banking, 40 for Protection of Environment). min 1 · max 50
`section`required	string	Section identifier as "part.section", e.g. "1026.43" or "240.10b-5". The part is the digits before the dot. match ^[0-9]{1,4}[a-zA-Z]{0,2}\.[0-9a-zA-Z][0-9a-zA-Z.\-]{0,18}$
`date`	string	Optional point-in-time date (YYYY-MM-DD). Returns the text in force on that date; coverage starts 2017-01-03. Defaults to the latest available text. match ^\d{4}-\d{2}-\d{2}$

Code samples

cURLbash

# 1. Probe with no auth → 402 envelope with PaymentRequirements
curl -sS 'https://2s.io/api/law/cfr-section?title=1&section=12345678&date=2024-01-01'

# 2. Sign + retry with PAYMENT-SIGNATURE:
curl -sS 'https://2s.io/api/law/cfr-section?title=1&section=12345678&date=2024-01-01' \
  -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/law/cfr-section?title=1&section=12345678&date=2024-01-01'

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.law.cfrSection({
  "title": 1,
  "section": "12345678",
  "date": "2024-01-01"
})

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.law.cfr_section(title=1, section="12345678", date="2024-01-01")

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": "law.cfr-section",
    "arguments": {
      "title": 1,
      "section": "12345678",
      "date": "2024-01-01"
    }
  }
}

Response

Field	Type	Description
`citation`	string	Canonical citation, e.g. "12 CFR 1026.43".
`title`	integer	CFR title number.
`part`	string	Part identifier (digits before the dot).
`section`	string	Full section identifier.
`heading`	string	Official section heading.
`text`	string	Plain-text body of the section.
`sourceCredit`	string	Federal Register source credit (citation history), when present.
`asOfDate`	string	Date (yyyy-mm-dd) the returned text reflects.
`truncated`	boolean	True if text was cut at the response cap (rare, giant sections only).
`url`	string	Official eCFR page for the section.
`source`	object

Example response datajson

{
  "citation": "example",
  "title": 1,
  "part": "example",
  "section": "example",
  "heading": "example",
  "text": "example",
  "sourceCredit": "example",
  "asOfDate": "example",
  "truncated": false,
  "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.