Cache-Control header directives in Rest API

Introduction

The Cache-Control header tells browsers and servers how to store and reuse web data. It helps make websites faster and saves internet data.

You want to make sure a webpage updates immediately when changed.

You want to let browsers keep a copy of images or files to load faster next time.

You want to prevent sensitive data from being saved in cache.

You want to control how long data stays fresh before checking for updates.

You want to improve website speed by reducing repeated downloads.

Syntax

Rest API

Cache-Control: directive1, directive2, ...

Directives are instructions like no-cache or max-age=3600.

Multiple directives are separated by commas.

Examples

Tells the browser to always check with the server before using cached data.

Rest API

Cache-Control: no-cache

Allows the browser to use cached data for 3600 seconds (1 hour) without checking the server.

Rest API

Cache-Control: max-age=3600

Prevents the browser and any caches from storing the response at all.

Rest API

Cache-Control: no-store

Marks the response as public and cacheable for 24 hours.

Rest API

Cache-Control: public, max-age=86400

Sample Program

This simple web server sends a Cache-Control header telling browsers to keep the page for 60 seconds before checking for updates.

Rest API

from flask import Flask, make_response

app = Flask(__name__)

@app.route('/')
def home():
    response = make_response('Hello, world!')
    response.headers['Cache-Control'] = 'public, max-age=60'
    return response

if __name__ == '__main__':
    app.run(debug=True)

Important Notes

no-cache means "check with server before using cached data" but still stores it.

no-store means "do not save this data anywhere" for privacy or security.

max-age sets how many seconds the data is fresh and can be reused without checking.

Summary

Cache-Control header controls how browsers and servers save and reuse web data.

Use directives like no-cache, no-store, and max-age to set caching rules.

Proper caching makes websites faster and saves data.