Token bucket vs sliding window vs fixed window — which rate limiter when?

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# System Design Deep Dive: Mastering Rate Limiting (Token Bucket vs. Sliding vs. Fixed Window)

**Target Audience:** Software Engineers preparing for System Design Interviews.
**Difficulty:** Easy to Medium
**Key Concepts:** API Gateways, Distributed Systems, Redis, DDoS Protection.

## 1. Introduction

In System Design interviews, whenever you design a public-facing API (e.g., Twitter, Stripe, or a URL shortener), the interviewer will inevitably ask: *"How do you protect your service from abusive clients, buggy scripts, or DDoS attacks?"*

Your answer must be: **Rate Limiting**.

Rate limiting controls the rate of traffic sent or received by a server. However, saying "I will use a rate limiter" is not enough. You must know *which algorithm* to use, the trade-offs, and how to implement it in a distributed environment.

In this guide, we will break down the three industry-standard algorithms: **Fixed Window**, **Sliding Window**, and **Token Bucket**.

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## 2. Algorithm 1: Fixed Wind

Token bucket vs sliding window vs fixed window — which rate limiter when?

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System Design Deep Dive: Mastering Rate Limiting (Token Bucket vs. Sliding vs. Fixed Window)

1. Introduction

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Understand the problem

Attempt it yourself

Study the solution

System Design Deep Dive: Mastering Rate Limiting (Token Bucket vs. Sliding vs. Fixed Window)

1. Introduction

Solution ready — 2 min read

Join the discussion

Discussion (0)

KEEP THESTREAK ALIVE.

KEEP THE
STREAK ALIVE.