API Rate Limiter

A Java simulation of API rate limiting that tracks user requests and blocks users after they exceed a predefined limit.

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How It Works

Each incoming request is associated with a user.

• If the user has not reached the request limit, the request is allowed.
• If the user has already reached the limit, the request is blocked.
• Request counts are tracked separately for each user.

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Features

• Tracks requests per user
• Enforces a maximum request limit
• Blocks requests that exceed the limit
• Displays request statistics
• Console-based simulation

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Example Output

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Testing

This project uses JUnit 5 and Maven for unit testing.

Covered Test Cases

• Allows a new user's first request
• Allows requests up to the configured limit
• Blocks requests after exceeding the limit
• Maintains independent request counts for different users

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Concepts Used

• Java Collections
• JUnit 5
• Unit Testing
• Maven
• HashMap
• Object-Oriented Programming

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Why I Built This

Rate limiting is a common technique used by APIs and web services to control traffic and prevent abuse.

This project was built to explore how backend systems enforce request limits using in-memory data structures. It demonstrates per-user request tracking, simple business logic, and unit testing with JUnit 5.

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Run Locally

1. Clone the repository:

git clone https://github.com/JavaLabs-io/RateLimiter.git

2. Navigate to the project directory:

cd RateLimiter

3. Run the unit tests:

mvn test

4. Run the application by opening RateLimiter.java in your IDE (such as VS Code, Eclipse, or IntelliJ IDEA) and executing the main() method.