claude-sonnet-api
POST https://x402.agentindex.world/llm/claude-sonnet
Claude Sonnet API - pay per call, no API key. OpenAI-format chat completions on anthropic/claude-sonnet-5.5, pinned to Anthropic'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/claude-sonnet/sample.
Warnings
Price mismatch The live price differs from the catalogue listing.
How to buy
This endpoint takes pay-per-call payments over x402. Call it once without paying to see its live price; any x402 client then pays and retries automatically.
curl -i -X POST "https://x402.agentindex.world/llm/claude-sonnet"
# HTTP/1.1 402 Payment Required: price, asset and payTo are in the responseRecent checks
| Checked (UTC) | Result | Status | Time | Live price |
|---|---|---|---|---|
| 2026-10-11 10:01 | Valid 402 | 402 | 622 ms | $0.011 |
| 2026-10-11 05:45 | Valid 402 | 402 | 437 ms | $0.011 |
| 2026-10-11 01:15 | Valid 402 | 402 | 834 ms | $0.011 |
| 2026-10-10 20:45 | Valid 402 | 402 | 345 ms | $0.011 |
Receipts
No test purchases yet. Graded test purchases are next on our list; until then every number here comes from unpaid checks.
What a check proves