
Sky Live HTTP Headers
WebSniffer
HTTP-Repeater (HTTP/s Live Headers) (Beta)
HTTP Header Analyzer
HTTP-TRACKER
Requestly
HTTP Header Spy
Modify Header Value (HTTP Headers) is a browser extension that allows you to add, modify or remove a header for any request to your preferred domains.

The modern platform for creating, sharing, and collaborating on AI prompts. Advanced version control and real-time testing.

Which is more popular?
Based on our record, Modify Header Value (HTTP Headers) seems to be more popular. It has been mentioned 4 times since March 2021.
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| Website | mybrowseraddon.com | diffyn.com |
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As answered by people managing Modify Header Value (HTTP Headers) and Diffyn.
Diffyn's answer:
Addresses workflow and change management on LLM prompts, provide teams with traceability and visualization of tests across multiple models, provide deeper understading into efficiency of these prompts.
Diffyn's answer:
Diffyn is the platform that specializes on both change management and multi-model analysis.
Diffyn's answer:
React, Next.js, POSTGRESQL
Diffyn's answer:
Professionals incorporating LLMs or AI tools in their workflow and wants to keep track of changes and test their prompts.
Diffyn's answer:
I started working on Diffyn when I notice that prompting has become an essential part of work across many industries. While there are version control platofrms like github, they are not designed for just prompt management are can be overkill such applications, it is also not integrated natively with various LLMs and relevant tools for users to validate ideas and visualise results properly.
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Recommendations tracked on public social media and blogs since March 2021.


Yep that started recently. I found a solution with the add-on Modify Header Value (HTTP Headers) , you need to add two rules:. Source: about 3 years ago
Going off of what a user said in the comments of another post complaining about this, you can get the old behaviour back by modifying the request headings. I've managed to do this using a Chrome extensions called Modify Header Value... Source: over 3 years ago
To change user agent on fenix (nighlty ,using custom collection )I use https://mybrowseraddon.com/modify-header-value.html It can also modify other header parameters . Source: over 4 years ago
Tracking Diffyn since Jun 2025.
When comparing Modify Header Value (HTTP Headers) and Diffyn, you can also consider the following products.

Sky Live HTTP Headers is an open-source browser extension that visually displays HTTP requests and response headers from every website you visit.
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WebSniffer is an online tool to outlook HTTP request and response headers.
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HTTP-Repeater (HTTP/s Live Headers) (Beta) is a browser extension that lets you capture browser requests and repeat the process in a loop automatically.
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HTTP Header Analyzer is an open-source browser extension that allows you to see and analyze the current HTTP request and response header from the website URL.
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HTTP-TRACKER is an advanced browser extension that allows you to examine HTTP request headers, cookies, response Headers, website data, cookies and modify request headers before sending them.
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