Introduction

The modern, type-safe rate limiting library for Python and TypeScript.

Halt is designed to be the last rate limiter you'll ever need. Whether you're building a simple API or a complex multi-tenant SaaS platform, Halt provides the primitives and high-level abstractions to protect your resources effectively.

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At a Glance

Performance First

Optimized for low latency with O(1) memory usage per key and efficient storage patterns.

SaaS Ready

Built-in support for multi-tenancy, quotas, tiered plans, and penalty systems.

Storage Agnostic

First-class support for Redis, Postgres, MongoDB, DynamoDB, Memcached, and Memory.

Developer Experience

Fully typed, intuitive APIs, and comprehensive documentation for both Python and TS.

How it Works

graph LR
    Client[Client] --> LB[Load Balancer]
    LB --> App[Application / Middleware]
    
    subgraph Halt Logic
    App -- Check Limit --> Limiter[Rate Limiter]
    Limiter -- Get/Set --> Store[(Storage Backend)]
    Store -- Result --> Limiter
    Limiter -- Allowed/Blocked --> App
    end
    
    App --> API[API Logic]

Halt intercepts requests at the application or middleware layer, checks usage against the storage backend, and decides whether to allow or block the request.

Simple Example

Protecting an endpoint is as simple as defining a limiter and applying it.

Python

import redis
from halt import RateLimiter, RedisStore, presets

limiter = RateLimiter(
    store=RedisStore(client=redis.Redis.from_url("redis://localhost:6379")),
    policy=presets.PUBLIC_API,
)

if not limiter.check("user:123").allowed:
    raise RateLimitExceeded()

TypeScript

import Redis from 'ioredis';
import { RateLimiter, RedisStore, presets } from 'halt-rate';

const limiter = new RateLimiter({
  store: new RedisStore({ client: new Redis(process.env.REDIS_URL) }),
  policy: presets.PUBLIC_API
});

const result = await limiter.check("user:123");
if (!result.allowed) {
  throw new RateLimitExceeded();
}

Next Steps

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