Authentication

Base Screener supports two authentication methods: x402 payments for production and API keys for development.

x402 payments (production)

1. Send Query — POST your GraphQL query to the API without any auth headers
2. Receive 402 — Server calculates query complexity and responds with HTTP 402 Payment Required
3. Sign Payment — Your agent constructs a Permit2 gasless USDC authorization
4. Retry — Re-send with the signed payload in the PAYMENT-SIGNATURE header
5. Receive Data — Payment is verified and settled via Coinbase facilitator, data is returned

Using a library like Coinbase AgentKit automates this entire flow — the 402 → sign → retry cycle is handled transparently.

See How x402 Payments Work for the full protocol breakdown.

API keys (development)

For testing during development, pass the X-API-Key header to bypass x402:

bash
curl -X POST https://apitoken.agentchaintools.xyz/graphql \
  -H "Content-Type: application/json" \
  -H "X-API-Key: sk_test_your_key_here" \
  -d '{"query": "{ newTokens(limit: 3) { tokens { symbol } } }"}'

API keys have a credit balance (in complexity units) that decreases with each query. When credits run out, the API returns 402 and you'll need to top up or switch to x402 payments.

GraphQL introspection

Standard GraphQL introspection (__schema, __type queries) is always free — no payment or API key required. This lets agents discover the schema dynamically.

Schema endpoint

bash
curl https://apitoken.agentchaintools.xyz/schema

Returns the raw GraphQL SDL as plain text. Cached for 1 hour. No auth required.