ratelane-sdk

API observability and live policy control plane middleware for FastAPI.

Ratelane gives you fleet-wide visibility and real-time policy enforcement — rate limits, route enable/disable, per-route timeouts, CORS, IP rules, circuit breakers, and request size limits — without redeploying your app. Policy changes push to all instances within 10 seconds.

Installation

pip install ratelane-sdk

Quick start

from fastapi import FastAPI
from ratelane import RatelaneConfig, RatelaneMiddleware

app = FastAPI()

app.add_middleware(
    RatelaneMiddleware,
    config=RatelaneConfig(
        api_key="your_api_key",
        collector_url="https://api.ratelane.dev",
        fastapi_app=app,
        # instance_version="1.0.0",  # optional: your app version
        # framework="fastapi",        # optional: override auto-detection
    )
)

Features

• Rate limiting — global and per-route, enforced locally with no network call on the hot path
• Route control — enable/disable routes with custom status codes and messages
• Per-route timeouts — automatic 504 on slow downstream responses
• CORS — dynamic allowed origins pushed from the dashboard
• IP allowlist / denylist — global and per-route, supports exact IPs and CIDR ranges
• Request size limits — Content-Length fast path + chunked stream enforcement
• Circuit breaker — per-route sliding window, automatic open/half-open/closed transitions
• Emergency Profile — automatic fallback policy when the policy server is unreachable, auto-reverts on reconnect
• Fleet visibility — per-instance sync status, runtime info, SDK version, and policy signature in the dashboard

Configuration

CLI

# Clear state for this project
ratelane clear --collector-url https://api.ratelane.dev --api-key sk_live_...

# Clear all Ratelane state on this machine
ratelane clear --all

License

Copyright 2026 Ratelane. All Rights Reserved.