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HTTP Cache Header Generator

Visually build Cache-Control headers with directives explained.

Generated Header

Cache-Control: (none)

Presets

About this tool

The Cache-Control header is a fundamental part of HTTP caching that controls how browsers, CDNs, and proxies store and reuse content. Configuring it correctly is essential for web performance β€” getting it wrong can lead to stale content being served to users or unnecessary server load from cache misses. However, the syntax is complex, with multiple directives and their interactions often confusing even experienced developers.

This tool provides a visual builder for Cache-Control headers, letting you toggle individual directives and see the generated header in real time. Instead of memorizing syntax like `public, max-age=3600, s-maxage=7200, stale-while-revalidate=86400`, you select options through an intuitive interface and copy the final header directly into your HTTP responses. Preset templates for common scenarios β€” static assets, API endpoints, HTML pages, and CDN-cached content β€” jumpstart your configuration without guesswork.

Web developers, DevOps engineers, and backend specialists will find this tool invaluable for debugging cache issues, setting up CDN caching policies, or learning how different directives interact. The generated header can be copied directly into your server responses (Express.js, FastAPI, Java, Go, etc.), eliminating manual transcription errors and speeding up caching strategy implementation.

Frequently Asked Questions

Code Implementation

from flask import Flask, make_response, send_file
import hashlib
import time

app = Flask(__name__)

@app.route('/static/asset')
def serve_immutable_asset():
    """Cache forever β€” content-hashed file (e.g., bundle.abc123.js)"""
    response = make_response("asset content")
    response.headers['Cache-Control'] = 'public, max-age=31536000, immutable'
    return response

@app.route('/api/data')
def serve_api_data():
    """Short-lived private API response with ETag"""
    data = "dynamic content"
    etag = hashlib.md5(data.encode()).hexdigest()

    response = make_response(data)
    response.headers['Cache-Control'] = 'private, max-age=60'
    response.headers['ETag'] = f'"{etag}"'
    return response

@app.route('/page')
def serve_page():
    """HTML page: always check freshness, cache 10 minutes"""
    response = make_response("<html>...</html>")
    response.headers['Cache-Control'] = 'public, max-age=600, must-revalidate'
    response.headers['Last-Modified'] = 'Mon, 01 Jan 2024 00:00:00 GMT'
    return response

@app.route('/auth')
def serve_auth_page():
    """Never cache sensitive pages"""
    response = make_response("sensitive content")
    response.headers['Cache-Control'] = 'no-store'
    return response

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