fx.rates

Daily reference exchange rates from the European Central Bank (via Frankfurter). 30+ major currencies. Pass base = 3-letter ISO 4217 currency (default USD), optional symbols = comma-separated target codes (default = all available), optional date = YYYY-MM-DD for historical rates (history back to 1999, business days only; omit for latest), optional amount to convert (default 1). Returns base, date, amount, and a map of currency code → rate.

price

$0.0012 USDC per call

method

GET/api/fx/rates

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
`base`	string	match ^[A-Za-z]{3}$
`symbols`	string	min 3 chars · max 200 chars
`date`	string	match ^\d{4}-\d{2}-\d{2}$
`amount`	number	min 0 · max 1000000000

Code samples

cURLbash

# 1. Probe with no auth → 402 envelope with PaymentRequirements
curl -sS 'https://2s.io/api/fx/rates?base=USD&symbols=xxx&date=2024-01-01&amount=1'

# 2. Sign + retry with PAYMENT-SIGNATURE:
curl -sS 'https://2s.io/api/fx/rates?base=USD&symbols=xxx&date=2024-01-01&amount=1' \
  -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/fx/rates?base=USD&symbols=xxx&date=2024-01-01&amount=1'

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.fx.rates({
  "base": "USD",
  "symbols": "xxx",
  "date": "2024-01-01",
  "amount": 1
})

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.fx.rates(base="USD", symbols="xxx", date="2024-01-01", amount=1)

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": "fx.rates",
    "arguments": {
      "base": "USD",
      "symbols": "xxx",
      "date": "2024-01-01",
      "amount": 1
    }
  }
}

Response

Field	Type	Description
`base`	string
`date`	string
`amount`	number
`rates`	object
`source`	object

Example response datajson

{
  "base": "example",
  "date": "example",
  "amount": 1,
  "rates": {},
  "source": {
    "provider": "example",
    "url": "https://example.com",
    "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.