the402 endpoint detail

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api.webbersites.com api calc

https://api.webbersites.com/api/calc

payable

Exact math for agents — the arithmetic LLMs get plausibly wrong. Evaluates an expression at 50-significant-digit precision (BigNumber): big-integer multiplication, high-precision division, roots, logs, factorials, unit conversions (12 inch to cm). GET ?expr=…, result returned as an exact string. Deterministic, no AI, never executed as code.

We sent a real GET request to this endpoint and it answered 402 with payment requirements we could parse.
Price
$0.001
Network
base
Pay to
0xdd5fcEa81CA6f1EB39FEd5B973DE794293B81ba6
Spec dialect
v2 (declares x402Version 2)
Transport
PAYMENT-REQUIRED header
HTTP method
GET
Response latency
164 ms
Payment options
1 usable of 1
Last checked
2026-08-10T09:08:45.842Z (1d ago)
Category
ai-inference

Re-check it yourself:
curl "https://api.the402.dev/validate?url=https%3A%2F%2Fapi.webbersites.com%2Fapi%2Fcalc"