Firefox

Gecko — the one major engine that is neither Chromium nor WebKit.

What it does

Firefox’s real value is being a second rendering engine. A layout or CSS bug that only appears outside Chromium is invisible until something non-Chromium loads the page, and with Edge, Brave, Arc and Opera all being Chromium, Firefox is the practical way to catch it.

Its own strengths: Total Cookie Protection isolating cookies per site by default, container tabs for keeping identities separate, and a CSS inspector with genuinely better grid and flexbox tooling than Chrome’s.

Extensions

Firefox’s extension API is still the more permissive of the two: webRequest blocking works, so a content blocker can see and cancel a request rather than hand Chrome a list of rules and hope. Everything below installs from addons.mozilla.org.

Blocking and privacy

Extension	Does
uBlock Origin	The content blocker. Full `webRequest` version, which Chrome no longer allows
Privacy Badger	Learns which third parties track across sites and blocks those, rather than working from a list
PopUpOFF	Kills overlays, cookie walls and newsletter modals, with a per-site aggressiveness setting
DuckDuckGo Search & Tracker Protection	DuckDuckGo as the search default, plus tracker blocking and an email alias service
Facebook Container	Confines Facebook to its own container so its cookies cannot follow you off-site
FastForward	Skips link shorteners and “wait 10 seconds” gateway pages
User-Agent Switcher and Manager	Spoof the user agent per site, for the pages that refuse a browser by name

Credentials and keeping things

Extension	Does
Bitwarden	Autofill from the Bitwarden vault, including TOTP codes
Karakeep	One-click save to a self-hosted Karakeep instance, which archives and tags the page
Linkwarden	The same idea for Linkwarden — a bookmark manager that keeps a full snapshot
Tab Session Manager	Save and restore whole windows of tabs, with automatic periodic snapshots

Downloading and capture

Extension	Does
Video DownloadHelper	Detects media on a page and downloads it. Needs the companion app for anything that has to be muxed
MeTube Downloader	Sends the current URL to a self-hosted MeTube server, which runs yt-dlp for you
FireShot	Full-page screenshots, including the part below the fold

Sites worth improving

Extension	Does
Refined GitHub	Dozens of small GitHub fixes — one-click merge conflict resolution, linked issue previews, a usable diff
SteamDB	Price history, real review scores and Steam Deck compatibility, inline on the store page
Augmented Steam	Store and library additions — lowest recorded price, wishlist tools, region comparisons
Keepa	Amazon price history as a chart on the product page, with drop alerts

Changing how pages behave

Extension	Does
Tampermonkey	Runs userscripts against matching pages. Anything the other extensions do not cover
Progressive Web Apps for Firefox	Installs sites as standalone apps with their own windows and Dock icons — Firefox has no built-in PWA support, so this adds a native connector to do it

An extension sees every page you visit, and updates silently. Extensions change hands, and a popular one bought by an ad network is a recurring story. Install few, prefer ones with source you can read, and review the permission prompt — “read and change all your data on all websites” is exactly what it says.

Notes

Firefox self-updates. about:config still exposes every preference, which is the reason it survives as the browser of choice for people who want to change things Chromium hard-codes.

Alternative to

Alternative	Type	Trade-off
LibreWolf	Open source	A hardened Firefox fork with telemetry and Pocket stripped out
Waterfox	Open source	Another fork, more conservative about removing features
Safari	Built in	The other non-Chromium engine, and the one iOS users are on
Tor Browser	Open source	Firefox-based, for anonymity rather than everyday use