Introduction

In this project, we will explore the following three approaches for rate-limiting:

1. Token Bucket
2. Fixed Window
3. Sliding Window

Local Setup

To install all the dependencies:

yarn

To start the server run the following command:

yarn start

Once the server is up and running, to check the rate-limiter run this command in another terminal window:

yarn test

Rate Limiting

In simple words, rate-limiting is a simple way of handling how many requests you want your server to serve in a given time frame. For example, if your server has a capacity of handling a load of 50 requests per minute, you never want the server to reach that capacity, as you risk crashing the server. Therefore you put a hard and fast limit on your server that in a given time frame, it can process only a given number of requests, which in our example can be 40 requests/min. Rate limiting can also be handy when you deal with APIs provided by SaaS, as there are a limited number of API calls that you can make to a given end-point. If you exceed the given limit, either your requests are discarded or you have to pay more to increase the limit.

Depending upon the use-case, we can either decide to discard the requests received when the rate limit is reached or we can retry once the rate limit is restored.