nonprofit.search

US 501(c) nonprofit organization search. Lookup by 9-digit EIN (with or without hyphen), free-text name, 2-letter state, NTEE category code (e.g. 'B99' for education), or IRS subsection code (3 = 501(c)(3), 4 = 501(c)(4), etc.). Each record includes EIN, name, city/state, NTEE code, subsection code + human-readable subsection description (e.g. '501(c)(3) Charitable / Religious / Educational'), and relevance score. Sourced from ProPublica Nonprofit Explorer, which aggregates IRS Form 990 + BMF data; underlying IRS data is public domain.

price

$0.0012 USDC per call

method

GET/api/nonprofit/search

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
`q`	string	min 2 chars · max 200 chars
`ein`	string	min 9 chars · max 11 chars · match ^\d{2}-?\d{7}$
`state`	string	min 2 chars · max 2 chars · match ^[A-Za-z]{2}$
`nteeCode`	string	match ^[A-Za-z][0-9]{1,3}$
`subsectionCode`	integer	min 2 · max 92
`page`	integer	min 0 · max 99

Code samples

cURLbash

# 1. Probe with no auth → 402 envelope with PaymentRequirements
curl -sS 'https://2s.io/api/nonprofit/search?q=xx&ein=12345&state=xx&nteeCode=example&subsectionCode=2&page=0'

# 2. Sign + retry with PAYMENT-SIGNATURE:
curl -sS 'https://2s.io/api/nonprofit/search?q=xx&ein=12345&state=xx&nteeCode=example&subsectionCode=2&page=0' \
  -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/nonprofit/search?q=xx&ein=12345&state=xx&nteeCode=example&subsectionCode=2&page=0'

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.nonprofit.search({
  "q": "xx",
  "ein": "12345",
  "state": "xx",
  "nteeCode": "example",
  "subsectionCode": 2,
  "page": 0
})

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.nonprofit.search(q="xx", ein="12345", state="xx", nteeCode="example", subsectionCode=2, page=0)

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": "nonprofit.search",
    "arguments": {
      "q": "xx",
      "ein": "12345",
      "state": "xx",
      "nteeCode": "example",
      "subsectionCode": 2,
      "page": 0
    }
  }
}

Response

Field	Type	Description
`query`	object
`totalCount`	integer
`numPages`	integer
`returned`	integer
`organizations`	array
`source`	object

Example response datajson

{
  "query": {
    "q": "example",
    "ein": "example",
    "state": "example",
    "nteeCode": "example",
    "subsectionCode": 1,
    "page": 1
  },
  "totalCount": 1,
  "numPages": 1,
  "returned": 1,
  "organizations": [
    {
      "ein": "example",
      "einFormatted": "example",
      "name": "example",
      "subName": "example",
      "city": "example",
      "state": "example",
      "nteeCode": "example",
      "subsectionCode": 1,
      "subsectionDesc": "example",
      "score": 1
    }
  ],
  "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.