{"uid":"cap_QziYfwCl2JaGOzG0DjG92","slug":"gpt-mini-api-pay-per-call-chat-completions-5d2edb1c","name":"GPT Mini API (Pay-per-call Chat Completions)","description":"GPT Mini API - pay per call, no API key. OpenAI-format chat completions on openai/gpt-5.4-mini, pinned to OpenAI's own OpenRouter endpoint for reliability. You sign a fixed price computed from your max_tokens; unused tokens are not refunded. 20s server-side timeout - never charged if it fires; set your client timeout to 30s. Try GET /llm/gpt-mini/sample.","url":"https://x402.agentindex.world/llm/gpt-mini?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","properties":{"messages":{"type":"array","items":{"type":"object"},"minItems":1,"description":"OpenAI-format chat messages: [{role, content}, ...]."},"max_tokens":{"type":"integer","description":"Max completion tokens, capped at 4096 - also bounds the price ceiling."}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005069","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005069/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005069","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005069","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_x4F61RDPhixrNgHGCIEhd","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005069","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Pay-per-call OpenAI-format chat completions using GPT-4o-mini via OpenRouter, with no API key required — billed per request via x402 micropayment.","exampleAgentPrompt":"Ask the AI: 'What are three creative names for a coffee brand focused on sustainability?' — use up to 200 tokens for the response.","exampleUseCases":[{"title":"Quick LLM answer without API key","prompt":"I need a one-off GPT response to this question: 'Explain the difference between REST and GraphQL in two sentences.' Use up to 150 tokens and bill me per call — I don't want to set up an OpenAI account."},{"title":"Automated chatbot reply generation","prompt":"My support bot needs a reply to a customer message: 'Where is my order?' — generate a polite holding response using GPT, max 100 tokens, and charge me per call."},{"title":"Dynamic content generation in a pipeline","prompt":"In my data pipeline, generate a one-paragraph product description for 'wireless noise-cancelling headphones for remote workers' — keep it under 200 tokens and use the pay-per-call GPT endpoint so I'm not locked into a monthly plan."}],"resultDescription":"Returns an OpenAI-format chat completion object containing the assistant's generated reply text, finish reason, and token usage details. The response mirrors the standard OpenAI /v1/chat/completions response shape.","failureModes":["20-second server-side timeout fires — request is never charged but the client receives no completion","max_tokens exceeds 4096 cap — request may be rejected or clamped","Malformed messages array (missing role or content) — likely a 4xx validation error","Payment failure or insufficient USDC balance — x402 payment rejected before processing","Network timeout on client side if client timeout is set below 30s — client should use 30s minimum"],"whenToPreferThis":"Choose this endpoint when you need a quick, keyless GPT-4o-mini chat completion without setting up an OpenAI account or managing API credentials. Ideal for agents that make infrequent or unpredictable LLM calls and want transparent per-call USDC pricing with a known cost ceiling set by max_tokens. Not suitable for streaming responses, long context windows beyond 4096 tokens, or high-volume workloads where a direct OpenAI subscription would be cheaper.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-01T06:43:24.331Z","isFirstParty":false,"canonicalSlug":"gpt-mini-api-pay-per-call-chat-completions-5d2edb1c"}