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CheapestInference Anthropic Messages API
x402
CheapestInference Anthropic Messages API is a paid API for AI agents from api.cheapestinference.com, paid per call via x402, $20/call, status unknown (last checked 2026-09-14).
Send messages to Anthropic-compatible AI models via a flat-rate OpenAI-compatible API endpoint, paying per call rather than per token
Price / call$20
Success—
StatusUnknown
How this service works
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.
Output
Returns a JSON object with a content array containing the assistant's text response, following the Anthropic messages API response format
Example use cases
Example prompt
“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.”
Technical details
Endpoint
POSThttps://api.cheapestinference.com/anthropic/v1/messagesWhen to prefer
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
Side effects
- 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
Output
Schema · Response
| Field | Type | Description |
|---|---|---|
| content | array |
Tags
x402
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