Request filtering means examining and controlling the data that flows through your API gateway. When you use request filtering, you decide which requests should be allowed, blocked, or modified before they reach your backend services. This process helps protect your APIs from unwanted or harmful traffic, such as unauthorized users, suspicious data, or malicious attacks. By filtering requests, you create an extra layer of security, making sure only safe and valid requests reach your application.

How API Gateways Inspect and Filter Requests

API Gateways act as the main entrance for all requests going to your backend services. Every time a client sends a request, the API Gateway checks the request before letting it through. This process is called filtering.

What Does Filtering Do?

Filtering helps you:

• Check if the request contains all required information;
• Block requests with invalid or harmful data;
• Enforce rules like rate limits or authentication;
• Protect your backend from attacks, such as sending too much data or using the wrong format.

Simple Example

Imagine you have an online store. You want to make sure only valid orders reach your backend. The API Gateway can:

• Inspect every incoming order request to see if it has a valid product ID and quantity;
• Block any request that tries to order a negative number of items or uses a fake product ID;
• Reject requests missing important details, like customer address or payment info.

How Filtering Works in Practice

When a request arrives, the API Gateway might:

• Check the request headers for an authentication token;
• Validate the data format, such as making sure numbers are numbers and emails look correct;
• Limit how many requests each user can send in a minute to prevent abuse.

If a request does not meet the rules, the API Gateway blocks it and sends back an error message. Only requests that pass all the checks are forwarded to your backend services.

This helps keep your system secure, reliable, and easy to manage.