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Claude Sonnet 4.6 via x402engine (Pay-per-call)
x402
Claude Sonnet 4.6 via x402engine (Pay-per-call) is a paid API for AI agents from x402engine.app, paid per call via x402, $0.042592/call, status unknown (last checked 2026-10-12).
Calls Anthropic's Claude Sonnet 4.6 LLM via a pay-per-call HTTP 402 micropayment endpoint, returning an OpenAI-compatible chat completion response.
Price / call$0.042592
Success—
StatusUnknown
How this service works
125 production APIs behind HTTP 402 micropayments. 87 LLMs, Kling V3 and Hailuo video generation, image generation, code execution, travel search, web scraping, TTS, and transaction simulation. Pay with USDC on Base, USDm on MegaETH, or USDC on Solana.
Output
Returns an OpenAI-compatible JSON chat completion object containing the model name (anthropic/claude-sonnet-4.6), a choices array with the assistant message content and finish reason, and optionally tool call payloads if tools were invoked.
Example use cases
Agentic reasoning step with tool calls
“I need Claude Sonnet 4.6 to reason over this data and decide which of these three tools to call next — pass it the conversation history and the function definitions for search, calculate, and summarize, then return whatever tool call it picks.”
Per-call LLM for serverless app
“My serverless app needs to call Claude Sonnet 4.6 once per user request without a monthly API subscription — send this user message and system prompt to Claude and return the assistant reply, paying per call in USDC.”
Streaming Claude response for chat UI
“Stream a Claude Sonnet 4.6 response to the user's question 'What are the pros and cons of nuclear energy?' with a system prompt saying 'Be concise and balanced' — I need SSE streaming so the UI updates in real time.”
Technical details
Endpoint
POSThttps://x402engine.app/api/llm/claude-sonnet-4.6?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need Claude Sonnet 4.6 specifically (not a generic LLM), want pay-per-call billing in USDC/crypto without a monthly Anthropic subscription, are building an AI agent that handles its own micropayments via HTTP 402, or need OpenAI-compatible response format from a Claude model. Prefer over Anthropic's direct API when you want crypto-native billing or don't want to manage API key subscriptions.
Side effects
- Insufficient USDC/crypto balance causes 402 payment required failure
- Malformed messages array (missing required role or content/tool_calls) causes 400 validation error
- Exceeding model context length causes truncation or 400 error
- Unsupported parameters (top_k, top_p) if model capability not available per /docs/llm-capabilities.md
- Streaming requested but client does not handle SSE correctly leading to garbled output
- Network timeout on long generations
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"model": "anthropic/claude-sonnet-4.6",
"choices": [
{
"index": 0,
"message": {
"role": "assistant",
"content": "Hello!"
},
"finish_reason": "stop"
}
],
"content": "Hello!"
}
}Tags
x402
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