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FreeTier Sentinel API

Curated free-tier limits, paid per-call by AI agents via the x402 protocol. USDC on Base. No accounts, no API keys.

Quick start

Free endpoint — list providers and pricing:

curl https://freetier-sentinel.dev/v1/providers

Paid endpoint — call without payment, get HTTP 402 with payment requirements:

curl -i https://freetier-sentinel.dev/v1/cloud/cloudflare/limits

Then a x402-compatible client (e.g. Coinbase's @x402/fetch) signs the USDC transfer, retries with the X-PAYMENT header, and gets the response.

Endpoints

FREE GET /v1/providers

List all providers and categories we have data for. Use this to discover what's available before paying.

$0.005 GET /v1/limits/{provider}

All limits for a provider, every category. Returns an array of structured limit records.

$0.005 GET /v1/cloud/{provider}/limits

Cloud + CI limits for a provider. Filtered subset of /v1/limits/{provider}.

$0.005 GET /v1/ai/{provider}/limits

AI/LLM API limits for a provider (Gemini, OpenAI, Groq, etc.).

$0.01 GET /v1/compare?providers=a,b,c

Multi-provider comparison. Optional &category=cloud to filter. Minimum 2 providers.

Response schema

{
  "provider": "cloudflare",
  "limits": [
    {
      "provider": "cloudflare",
      "service": "workers",
      "category": "cloud",
      "metric": "requests",
      "limit": 100000,
      "unit": "requests",
      "period": "day",
      "notes": "Resets at 00:00 UTC...",
      "source_url": "https://developers.cloudflare.com/...",
      "as_of": "2026-05-06"
    }
  ],
  "count": 3,
  "schema_version": 1
}

x402 protocol

This API uses x402, an open HTTP-based payment standard. AI agents (or anyone with a USDC wallet on Base) can pay per-call without subscriptions, accounts, or API keys.

OpenAPI spec

Machine-readable spec for AI agents and SDK generation: /v1/openapi.json

Updates

Limit data is verified manually against provider docs. Each record has an as_of field. Contact support@freetier-sentinel.dev if you find a stale entry.

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