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:
Strong open-source alternatives (browser extensions or desktop apps)
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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”.
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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
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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.
Other good open-source options (more API client + some interception)
If you’re okay with a tool that’s stronger on API testing but still offers interception/modification:
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Hoppscotch (formerly Postwoman) — Fully open-source, lightweight API client with request interception in browser contexts.
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Bruno — Open-source, Git-friendly API client (local files, no cloud required).
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Insomnia (core is open-source) — Great for API work, with some proxy/interception capabilities.
Quick comparison table for interception focus
| 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!
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