LeechBlock NG, built and maintained by independent developer James Anderson under the handle "proginosko," is a free, open-source browser extension with some of the most sophisticated scheduling logic researched for this entire comparison set — up to 30 independently configurable rule sets, combining time windows, rolling time budgets and keyword-based blocking. It's also refreshingly honest about its own limits, which is a rarer quality in this category than it probably should be, given how many competitors imply a stronger guarantee than their actual mechanism delivers. Anderson has maintained LeechBlock as a personal, non-commercial project for many years, continuing to ship updates and respond to user-reported bugs without ever adding a paid tier, an account system, or any form of monetisation at all.
What LeechBlock actually does
LeechBlock blocks sites by URL pattern across up to 30 separate, independently configurable rule sets, combining time-of-day windows, rolling time budgets, and keyword matching, giving genuinely granular control over exactly when and how each individual site gets restricted. A "Lockdown" mode enables immediate blocking, and an optional password can gate access to the options page for anyone who wants a slightly firmer version of the default setup. It runs on Firefox (desktop and Android), Chrome, Edge and other Chromium browsers, giving it a genuinely broad footprint across the browser market. LeechBlock's keyword-blocking feature can also catch distracting content across sites you haven't explicitly listed, which is a genuinely more thorough approach than a plain domain blocklist most free competitors in this comparison set offer instead.
Where LeechBlock is honestly the better pick
Free, open-source, with no account or data collection, and genuinely more configurable scheduling than almost anything else in this comparison set — 30 independent rule sets is a level of granularity most paid competitors don't match, let alone a free one. For a browser-based distraction problem where you want fine control over exactly when and how blocking applies, that configurability is a real strength that's hard to find bundled with a genuinely free price tag anywhere else in this comparison set. It's also worth noting that LeechBlock's 30 independent rule sets can be named and organised by purpose — one for social media, one for news sites, one for a specific project deadline — giving a level of intentional structure a single flat blocklist doesn't offer.
| Feature | LeechBlock | Mr. Grummel |
|---|---|---|
| Platforms | Firefox (desktop and Android), Chrome, Edge and other Chromium browsers — browser extension only, no native mobile app | iOS & Android (in development) |
| Core mechanism | URL-pattern blocking across up to 30 configurable rule sets, combining time windows, time budgets and keyword blocking | Answer a quiz question from the app's curriculum to unlock |
| Self-bypassable? | Yes, and the developer says so directly — the password gate is self-chosen and self-resettable, and on Firefox Android there's no way to stop a user from just opening the menu and disabling it; the project's own docs recommend against using it as a parental-control tool for this reason | Not yet released — can't be assessed |
| Physical hardware required? | No | No |
| Price | Free, open-source, no paid tier | Not yet announced — join the waiting list |
The one mechanical difference that actually matters
LeechBlock is candid, in its own documentation, that it's an honor-system tool for the person using it — sophisticated scheduling, but no real defence against that same person simply opening the extension menu and turning it off whenever they decide the rule no longer applies. Mr. Grummel's quiz question isn't a setting sitting in a menu waiting to be toggled; it's the thing that has to be dealt with directly, every single time, with no configuration screen offering a quieter way out for anyone who's decided in the moment that today is an exception. It's also worth adding that this honesty is itself unusual in the category — plenty of competitors imply a stronger guarantee than their actual mechanism delivers, and LeechBlock's documentation deserves real credit for stating its own limits plainly rather than overselling what a browser extension can realistically achieve.
Who should pick which
If you want free, highly configurable browser blocking and you're honest with yourself that you won't just disable it in a weak moment, LeechBlock's scheduling depth is hard to match anywhere else in this comparison set, paid or free. If you've noticed that any settings menu eventually gets opened, sooner or later, and you want something with no equivalent off-switch at all, that's the harder line Mr. Grummel is built to hold, on your phone rather than in your browser. It's also worth trying LeechBlock specifically if your distraction problem is genuinely complex and multi-part — different sites at different times for different reasons — since few other tools in this comparison set offer anywhere near the same scheduling depth for free. It's also worth remembering that LeechBlock's honesty about its own limits is a genuinely rare quality worth rewarding with your attention, even if the underlying mechanism ultimately isn't strict enough for your particular situation. A tool that tells you exactly what it can't do is, in its own way, more trustworthy than one that quietly implies a strength it doesn't actually have.