{"uid":"cap_yPFsCPPkwjZYtZ9FdKxc4","slug":"cheapestinference-anthropic-messages-api-361fdb06","name":"CheapestInference Anthropic Messages API","description":"Access 200+ open-source AI models through a single OpenAI-compatible API. Flat-rate pricing with no per-token charges. Pay with card or USDC on Base.","url":"https://api.cheapestinference.com/anthropic/v1/messages","method":"POST","headers":{},"bodySchema":null,"responseSchema":{"type":"object","properties":{"content":{"type":"array"}}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"10","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":"$20/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"20","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"20","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_rz_Wx2B7zdJfnlHREXa6d","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"20","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Send messages to Anthropic-compatible AI models via a flat-rate OpenAI-compatible API endpoint, paying per call rather than per token","exampleAgentPrompt":"Using CheapestInference's Anthropic messages endpoint, send this message to claude-3-5-sonnet: 'Summarize the key risks of investing in small-cap stocks in 3 bullet points.' Pay the flat $10 USDC fee and return the response.","exampleUseCases":null,"resultDescription":"Returns a JSON object with a content array containing the assistant's text response, following the Anthropic messages API response format","failureModes":["Payment not provided or insufficient USDC — 402 Payment Required","Invalid model identifier — 400 Bad Request with unsupported model error","Malformed messages array — 400 Bad Request with schema validation error","Model temporarily unavailable — 503 Service Unavailable","Rate limit exceeded — 429 Too Many Requests","Network timeout on long completions — 504 Gateway Timeout"],"whenToPreferThis":"Prefer this endpoint when you want to use Anthropic-compatible message formatting (Claude API format) and prefer flat-rate per-call pricing over per-token billing, especially when running longer prompts where token costs would otherwise be high, or when you want to pay with USDC on Base rather than a credit card","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T06:31:41.407Z","isFirstParty":false}