Skip to main content
These endpoints are pay-per-use and intended for AI agents and experimental use cases. Features and pricing may change. For production workloads, we recommend the standard API key authentication flow.

x402 Overview

x402 is an open payment protocol developed by Coinbase that uses HTTP 402 Payment Required responses to charge for individual API calls with instant stablecoin payments. Instead of signing up for an account and managing an API key, agents pay in USDC per request directly from a wallet. CoinStats exposes a pay-per-use surface covering every read-only endpoint in the CoinStats Public API — live coin prices, market data, news, insights, wallet balances and DeFi positions, plus shared portfolio reads.

How It Works

Every request to a protected endpoint follows the same three-step flow:
1

Request the endpoint

Send a normal GET request. Because no payment is attached, the gateway responds with HTTP 402 Payment Required — the response includes the required amount, currency, wallet address, and network.
2

Sign a USDC payment authorization

Your wallet signs an EIP-3009 transferWithAuthorization for the exact amount. The @x402/fetch client library handles this automatically; custom clients can sign with any EIP-712-compatible wallet.
3

Retry with the payment header

Send the same request again, this time with the X-PAYMENT header containing the signed authorization. The facilitator settles on chain and the gateway returns the data with an X-PAYMENT-RESPONSE receipt. A Set-Cookie: auth_token=... header is also issued — subsequent calls within one hour skip the facilitator entirely.

Authentication

No API key is needed. Point your client at the dedicated x402 subdomain and skip the x-api-key header:
Every path that exists at https://api.coinstats.app/v1 under the supported list below is gated by x402 at https://x402.coinstats.app.

Supported Endpoints

Every listed endpoint is a read-only GET. Prices are quoted in USDC and settle on Base mainnet (chain ID 8453). Endpoints marked with sharetoken require a sharetoken header — the CoinStats user shares a portfolio link from the mobile app and hands the token to the agent. See shareToken for how to obtain one.

Pricing & Payment Method

Pricing is tiered by the underlying data cost. Simple lookups (coin price, markets, news) are 0.001.Walletscopedqueriesare0.001. Wallet-scoped queries are 0.004. Heavy DeFi/portfolio aggregations are 0.040.04–0.05.

Request Example

Node.js — @x402/fetch

The first request triggers the 402 → sign → settle loop; subsequent calls within an hour reuse the auth_token cookie and skip the facilitator round-trip.

cURL — manual

The 402 challenge is returned in the payment-required response header (base64-encoded JSON). To settle manually you’d need to sign an EIP-3009 authorization and replay the request with X-PAYMENT. For any real workload, use the @x402/fetch client library above.

Response Example

The X-PAYMENT-RESPONSE header on a 200 contains the settlement receipt (transaction hash + facilitator ack) for record-keeping.

Discovery

CoinStats endpoints are discoverable by agents via two indexes:
  • CDP Bazaar — every paid call is indexed under https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources with full-text searchable descriptions and input/output schemas.
  • agentic.market — surfaces CoinStats in its AI-agent marketplace alongside other x402-enabled data services.

Further Reading