> ## Documentation Index > Fetch the complete documentation index at: https://docs.blockforecast.io/llms.txt > Use this file to discover all available pages before exploring further. # x402 Agent API: Micropayment-Native Market Access > The x402 Agent API lets AI agents create markets and query data by paying USDC directly — no API key, no OAuth, no signup. Payment is the authentication. The x402 Agent API is a micropayment-native API surface built on the [HTTP 402 Payment Required](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/402) protocol. Instead of issuing a long-lived API key, the server gates each request behind a USDC micropayment on Base L2. Your agent signs a payment authorization, includes it in the request header, and the server verifies and settles the payment before executing the call. For market creation specifically, it costs exactly \$1 USDC per market — no subscription, no quota, no dashboard required. ## Who this is for The x402 API is purpose-built for three categories of developer: **Autonomous AI agents** that need to interact with prediction markets without human involvement in the authentication flow. An agent can hold a private key, fund the wallet with USDC, and call the API indefinitely — no key rotation, no session management. **Automated systems and bots** where the overhead of the standard API key flow (signing in a browser, storing a key, handling key expiry) adds friction that doesn't make sense for a machine actor. **Developers who want pay-as-you-go pricing** for low-frequency queries — rather than maintaining an integration just to query the oracle feed occasionally, you pay \$0.001 per call only when you need it. ## How the x402 protocol works x402 is a lightweight HTTP extension built by Coinbase for the AI agent ecosystem. When you make a request to an x402-gated endpoint without a payment header, the server returns `402 Payment Required` with a JSON body describing the payment requirements. Your client constructs a USDC transfer authorization (using EIP-3009 `transferWithAuthorization`), signs it with your wallet's private key, and retries the request with the signed payload in the `X-PAYMENT` header. The server forwards the payload to the Coinbase CDP facilitator for settlement, and if valid, executes the request. The full protocol flow: ``` Client BlockForecast API Coinbase CDP │ │ │ │── GET /api/v2/x402/feed ──────────►│ │ │ │ │ │◄── 402 Payment Required ───────────│ │ │ { amount, currency, payTo, │ │ │ network, nonce } │ │ │ │ │ │ [sign USDC transferWithAuth] │ │ │ │ │ │── GET /api/v2/x402/feed ──────────►│ │ │ X-PAYMENT: │ │ │ │── verify + settle ────────►│ │ │◄── settlement confirmed ───│ │◄── 200 OK + response body ─────────│ │ ``` The entire round-trip typically completes in 3–5 seconds. ## Available endpoints | Endpoint | Price | Description | | --------------------------------- | ------- | --------------------------------------------------------------------------------------------------------------------- | | `GET /api/v2/x402/info` | Free | Lists all x402 endpoints, their prices, and the current payment requirements. Discovery endpoint — no payment needed. | | `GET /api/v2/x402/feed` | \$0.001 | Real-time market data feed snapshot — prices, volume, and active market list. | | `GET /api/v2/x402/oracle/resolve` | \$0.05 | Query the AI oracle for its current consensus on a given question. Returns probability and citations. | | `POST /api/v2/x402/markets` | \$1.00 | Create a new prediction market. Requires creator approval (one-time, per wallet). | Read-only endpoints (`info`, `feed`, `oracle/resolve`) are open to any wallet with USDC on Base. Only `POST /x402/markets` requires creator approval. ## x402 vs the standard API key | | Standard API key | x402 Agent API | | -------------------- | ----------------------------------------------------------------- | ------------------------------------------ | | **Authentication** | `X-API-Key` header (persistent key) | `X-PAYMENT` signed USDC transfer | | **Identity** | Wallet that signed the key issuance request | Wallet that signs each payment | | **Cost model** | Rate-limited (60 req/min default), no per-request charge | Pay per request, no burst limit | | **Signup required** | Wallet signature only (one-time) | None for read endpoints | | **Creator approval** | Required to `POST /public/markets` | Required to `POST /x402/markets` | | **Best for** | Bots, dashboards, trading integrations hitting the API repeatedly | AI agents, one-off queries, data pipelines | Both APIs run in parallel — you can use an API key for high-frequency reads and x402 for pay-per-query oracle resolution, all from the same agent wallet. ## The 4-step build Getting an agent to the point of creating markets involves four steps: Generate a wallet programmatically with `viem` or use any EVM-compatible wallet (MetaMask, Coinbase Wallet, a hardware wallet). Your agent needs to hold the private key to sign payments at runtime. Store the key in a secrets manager. Send USDC on Base mainnet to the agent's address. \$5 covers gas plus several market creations. Bridge from Ethereum via the [official Base bridge](https://bridge.base.org) or send directly from Coinbase. Visit [blockforecast.io/apply](/creators/apply), connect with the agent wallet address, and submit the form. Approval lands within 24 hours. This is a one-time step — the same wallet can create markets via the web, the public API, and x402 forever after. Use an x402 client (e.g. `x402-fetch` from Coinbase) to handle the payment flow automatically. See [Create a market via x402](/developers/x402-create-market) for the full implementation. ## Why we built this Prediction markets are particularly well-suited to autonomous AI agents: agents are good at probability estimation, they can identify gaps in market coverage faster than humans, and they have a natural incentive to create markets — every trade on a creator-owned market sends 0.5% back to the creator's wallet in real time. An agent that creates markets can become self-funding. x402 removes the last friction in that loop: the need for a human to approve an API key or complete an OAuth flow. The wallet that signs the payment *is* the authenticated identity. No persistent state, no session, no dashboard. ## Next steps Full step-by-step guide with working TypeScript code for the complete wallet → fund → approve → create flow. Submit your creator application — reviewed within 24 hours and valid across all BlockForecast surfaces.