BlockRun — Pay-per-call AI gateway

# BlockRun API Reference > Pay-per-call AI gateway. 66+ AI models (chat, image, video, music, and ElevenLabs text-to-speech) plus multi-chain blockchain RPC (40+ chains), real-time crypto data, sandbox compute, DEX aggregation, prediction markets, and phone & voice — all priced in USDC and settled on-chain via the x402 protocol. No API keys, no accounts, no subscriptions. ## Authentication All paid endpoints follow the **x402 HTTP payment protocol**. There are no API keys. 1. Send the request without payment → BlockRun returns **HTTP 402 Payment Required** with the price and a signed payment requirement in `x-payment-required`. 2. Sign a USDC payment locally (private key never leaves your machine). 3. Retry the same request with the `X-Payment` header containing the signed payment. 4. BlockRun verifies, fulfills the request, and settles on-chain. Receipt returned in `X-Payment-Receipt` and `X-Payment-Response`. OpenAI-compatible LLM/image/video endpoints additionally accept an `Authorization: Bearer <BLOCKRUN_API_KEY>` mode for users who pre-fund a wallet on the dashboard — useful for SDK ergonomics. Free models, free `/v1/models`, free `/v1/crypto|fx|commodity/*` endpoints, and `/v1/voice/call/{id}` (poll) require no payment. ## Base URLs | Network | Base URL | Currency | |---------|----------|----------| | Base Mainnet | `https://blockrun.ai` | USDC | | Solana Mainnet | `https://sol.blockrun.ai` | USDC | | Base Sepolia (testnet) | `https://testnet.blockrun.ai` | Test USDC | All endpoint paths in this document are relative to the chosen base URL. ## Agent Workflow 1. List available models / endpoints — `GET /v1/models` (LLMs) or `/api/openapi` (full OpenAPI 3.1 spec). 2. Discover pricing — every endpoint returns its price in the 402 body before you commit to paying. 3. Buy any prerequisite resource — e.g. for outbound voice calls, run `POST /v1/phone/numbers/buy` *before* `POST /v1/voice/call`. Receipts in `X-Payment-Receipt`. 4. Send the pai

{"openapi":"3.1.0","info":{"title":"BlockRun AI Gateway","version":"1.0.0","description":"Agent-native AI gateway. Pay-per-request with USDC on Base. No accounts or API keys required.","x-logo":{"url":"https://blockrun.ai/brand/logo-256.png","altText":"BlockRun"}},"servers":[{"url":"https://blockrun.ai"}],"paths":{"/api/v1/chat/completions":{"post":{"operationId":"chatCompletions","summary":"Chat Completions","description":"Access 40+ frontier LLMs with OpenAI-compatible API. Price depends on mo