modheader.com

What It Is

ModHeader is a browser extension for modifying HTTP request headers, response headers, Authorization headers, Cookie, Set-Cookie, and related values. The site says it has 800,000+ users and maintains a 4+ star rating on the Chrome Web Store. It is designed for web development and testing, with the core value of reducing the need to change server-side code just to debug headers, authentication, CORS, localization, and edge-case responses.

Core Features

ModHeader supports Chrome, Firefox, and Edge, and runs on Windows, MacOS, and Linux. It can add or override standard HTTP headers such as Authorization, X-Forwarded-For, Content-Security-Policy, Permissions-Policy, Access-Control-Allow-Origin, and more. It also supports URL filters, letting you restrict rules to specific domains or paths and reducing the risk of leaking sensitive headers to third-party sites. Profiles, checkbox toggles, and keyboard shortcuts make it easy to switch quickly between different users, roles, regions, or feature flags.

Its companion product, ModResponse, extends debugging to the response side: it can replay and edit API response bodies, modify HTTP status codes, add latency, simulate network errors, or reroute production-domain requests to localhost for testing services such as AdSense that depend on an official domain. The site also provides small utilities such as Test my headers, CSP editor, and Permissions-policy editor.

Pricing and Service

Most features are available in the free version of ModHeader. Pro costs $4 per month, $2/month when billed annually, or $24/year, and there is also a one-time payment option at $60. Pro includes unlimited rules and profiles, organization support, no ads, and also unlocks ModResponse Pro. Students and educators can apply for one free Pro license using a .edu email address. The refund policy states that within 30 days of purchase, if an issue cannot be resolved, a full refund is available. Support is available via [email protected], and the site says replies usually come within 24 hours on business days; Pro organizations can also get SAML/OIDC SSO support.

Pros, Cons, and Best Fit

Its strengths are that it is lightweight, focused on common use cases, usable for free, and genuinely useful for frontend developers, backend developers, and QA teams. It is especially well suited for testing CORS, login states, permissions, regional content, abnormal API responses, and slow-network scenarios. Its limitations are that it is primarily a browser extension and cannot fully replace a VPN, server-side proxy, or full mock platform. For example, modifying X-Forwarded-For does not actually hide your IP address and may not be trusted by every server. The collected text does not specify whether it is open source, supports self-hosting, what payment methods are available, or how accessible it is from China.

China Access

Based on the current text, it is not possible to determine direct access, payment, or account service availability in mainland China, so china_access can only be marked as unknown. If access or payment is restricted, alternatives to consider include Requestly, Postman, Charles Proxy, Fiddler, Proxyman, Mockoon, or browser DevTools.