
Requestly
modheader
Header Editor
RequestHeaders.com
VibeHeader
HTTP Header Live
Modify Header Value (HTTP Headers)
A local-first ModHeader alternative: rewrite HTTP request & response headers via Chrome's native declarativeNetRequest. No backend, no account, no telemetry.

Insomnia REST
MuleSoft Anypoint Platform
DreamFactory
RapidAPI for Mac
Hoppscotch
Apigee
AWS CloudTrail
The Collaboration Platform for API Development

Which is more popular?
Based on our record, Postman seems to be more popular. It has been mentioned 30 times since March 2021.
Website, pricing, platforms and company facts side by side.
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| Website | headerflex.app | postman.com |
| Pricing | — | |
| Platforms | — | |
| Company | — | Startup from India |
| Listed in |
What each product offers, as listed by its team.


Possible disadvantages
Possible disadvantages
An editorial look at what each product does well and who it suits.


No analysis of HeaderFlex.app yet.
Overall verdict
Why this product is good
Recommended for
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POST/CON 2018 workshop in review: Running Postman Collections
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How often each product is chosen within a category, 0–100% relative to the other.


Share your experience with using HeaderFlex.app and Postman. For example, how are they different and which one is better?
External articles and on-site reviews we used to compare the two products.


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Forking Existing Collections: One of Postman’s unique strengths is the ability to fork collections created by others. Developers can easily duplicate publicly available Postman collections, modifying them to fit their...
As the digital landscape evolves, the significance of APIs (Application Programming Interfaces) has surged, facilitating seamless communication between various software applications. Postman has been a leading tool in...
- Focus on specific needs: Does the tool excel at SOAP APIs or cater to microservices? - Resource usage: Does it handle complex projects without impacting system performance? - Script reusability: Does it allow for...
Recommendations tracked on public social media and blogs since March 2021.


Tracking HeaderFlex.app since Aug 2026.
Postman (postman.com) is a comprehensive API platform that goes beyond mocking, offering a full suite for API development, testing, and monitoring. With its mock server feature, Postman enables teams to simulate responses for various... - Source: dev.to / almost 2 years ago
Postman is a widely used tool for API testing and interaction. Its "Mock Servers" feature lets you create a mock version of your API, returning specific responses for testing. While useful, Postman may lack advanced mock server... - Source: dev.to / almost 2 years ago
Postman is a widely adopted tool for API design and development, offering an intuitive interface for creating, testing, and documenting APIs. It simplifies the API design process, allowing architects to quickly prototype and refine their... - Source: dev.to / about 2 years ago
When comparing HeaderFlex.app and Postman, you can also consider the following products.


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Free browser extension to modify HTTP request and response headers. No sign-up. Works on Chrome, Firefox, and Edge.
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Add custom HTTP request headers to any site. Set Authorization tokens, override Content-Type, inject debug headers per URL pattern. declarativeNetRequest. Free: 5 rules, Pro: unlimited.
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DreamFactory is an API management platform used to generate, secure, document, and extend APIs.
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