I thought I had found an useful tool.
Unfortunately, it became restricted, even if claimed as “open source” :
https://app.requestly.io/pricing
Any similar tool with no restrictions ?
I thought I had found an useful tool.
Unfortunately, it became restricted, even if claimed as “open source” :
https://app.requestly.io/pricing
Any similar tool with no restrictions ?
Relay is an open-source browser extension that lets you intercept and modify HTTP requests directly inside your browser. It doesn’t require an account or paid plan.
You install it and start intercepting requests immediately.
Relay can capture requests made by websites and APIs.
You can see:
This helps debug frontend apps and APIs.
You can edit requests before they are sent.
Examples:
This is useful for testing APIs or bypassing certain checks during development.
Relay can send requests manually like a mini Postman inside Chrome.
You can:
Relay lets you save request sessions so you can reuse them later for debugging or testing.
Relay is ideal if you want something:
There are 25+ tools similar to Requestly including Postman, mitmproxy, and Fiddler depending on your use case.
My recommendation
If you want something closest to Requestly but with no restrictions:
Relay
If you want something much more powerful:
mitmproxy
Requestly has indeed shifted to a more restricted model over time. While the core remains open-source on GitHub (requestly/requestly) and you can still use many features for free or self-host parts of it, the cloud-synced features, unlimited rules/mocks, team collaboration, and some advanced modifications now push toward paid plans (as seen on their pricing page). This is a common evolution for freemium dev tools.
Here are some solid similar tools that focus on being unrestricted, fully open-source, or truly free forever with no artificial limits on core interception/modification features:
Inssman A fully open-source Chrome/Firefox extension specifically for modifying HTTP requests and responses. Features: Custom rules to modify headers, change responses, block requests, redirects, custom HTML/CSS/JS/JSON injection, logging. No paid tiers or restrictions mentioned — completely free and open-source. GitHub: https://github.com/vvmgev/Inssman Chrome Web Store: Search for “Inssman: Open-Source: Modify HTTP Request”.
HTTP Toolkit Excellent open-source desktop app (with browser integration via extensions) for intercepting, viewing, debugging, and mocking HTTP(S) traffic. It works system-wide or per-browser, supports request/response modification, rules, breakpoints, and injecting custom responses/scripts. Fully free for most use cases, open-source core, no hard limits on rules or modifications (some advanced team/cloud features are paid, but local usage is unrestricted). Highly regarded as a modern Charles/Fiddler alternative. Website: https://httptoolkit.com
Tamper Dev (formerly Tampermonkey-like for requests, but focused on interception) Chrome extension that lets you intercept, inspect, and edit live HTTP requests/responses. Very powerful for on-the-fly modifications. Free, no mentioned restrictions.
If you’re okay with a tool that’s stronger on API testing but still offers interception/modification:
Hoppscotch (formerly Postwoman) — Fully open-source, lightweight API client with request interception in browser contexts.
Bruno — Open-source, Git-friendly API client (local files, no cloud required).
Insomnia (core is open-source) — Great for API work, with some proxy/interception capabilities.
| Tool | Type | Fully Open-Source | No Usage Limits | Modification Types | Desktop or Browser |
|---|---|---|---|---|---|
| Inssman | Browser extension | Yes | Yes | Headers, response, block, redirect, inject | Browser |
| HTTP Toolkit | Desktop + browser | Core yes | Yes (local) | Full proxy: mock, rewrite, breakpoints | Desktop/Browser |
| Request Interceptor | Browser extension | Partial? | Yes | Redirect/block, headers, query params | Browser |
| Easy Interceptor | Browser extension | Yes | Yes | Overwrite response for XHR/fetch | Browser |
Many users who got frustrated with Requestly’s limits have switched to Inssman or HTTP Toolkit for pure interception work without nagging upgrades.
If you tell more about your main use case (e.g., header mods only, API mocking, script injection, mobile debugging), I can narrow it down further!
Thanks. Well, this one looks a good alternative for me : https://httptoolkit.com/