Mozilla Firefox is a free and open-source web browser developed for Windows, OS X, and Linux, with a mobile version for Android.
Ranked in these QuestionsQuestion Ranking
Pro Strong HTML5 feature support
Pro Awesome customizability
Pro Free, open source and community driven
Pro Syncs between devices
Firefox Sync is an optional feature in Firefox that allows syncing bookmarks, passwords, and add-ons between devices.
Pro Automatically updated
Firefox is automatically updated on the platforms where it makes sense.
Pro Good font rasterizing
Font rasterizing on Windows is much better than in competitors. Even smaller text is clear and contrast.
Pro Strong developer tool
Pro Reader View
Reader View in Firefox allows users to read an article without any distractions by removing ads, unrelated elements and other distractive objects (similar to Microsoft Edge's Reading Mode and Safari's reader mode).
Pro Ethical and pragmatic company mission
The Mozilla Manifesto outlines the company's mission and principles. Paraphrasing, they want the Internet to be a free and open resource, and to enable individuals to get the best use of that resource. They do this by creating open source software to which anyone may contribute, so long as such contributions fit with their principles (both ethical and technical).
Pro Fast bookmark management
In order to add an open page to the bookmark bar, the tab can be dragged down and is added immediately.
Pro Tagging bookmarks
Firefox is one of the few browsers that you can tag your bookmarks. You can view a list of tags and can search your bookmarks in the address bar with tags.
Pro Lower memory fingerprint than competitors
Firefox used to be a trailer in memory usage, but as of 2017 it's less hungry for memory than competitors like Edge, Chrome, Safari and Opera.
Pro Integration with Pocket
Firefox comes with build-in Pocket integration that can allow users to quickly save the article for a read it later function to easily find any articles saved in Pocket from various sources and devices.
Pro Easy screenshots without extensions
Within the browser itself, you can easily take screenshots and save them to your computer.
Pro Text-to-speech (with adjustable speed) without add-ons
Firefox Reader Mode includes Narrate, a feature that adds text-to-speech functionality to the browser.
Con Installing some extensions still requires restarting the browser
While some of the developers already allow users to install their extensions without the need to restart the browser, not all of the extensions have been updated to support non-restart installation yet, as some developers have yet to add special code to do so.
Con Heavy and consumes a lot of memory
Mozilla developers should think on this as the new Microsoft Edge browser steals less memory and it just pops up the moment you open it. In the case of Mozilla, you have to wait for after clicking it for opening it.
Con Unstable add-ons
E10s has already caused many extensions to not work properly. Also, in November, only add-ons with WebExtension API can be installed.
Con Slow performance in OS X
Uses a lot of resources and feels slower than the Linux and Windows versions.
Con No support for ALSA since version 52
You must use PulseAudio if you need sound in Firefox.
Con Mozilla pushes political messages through it
Everyday on the standard page, there is a new message. Sometimes this message can be political (when this happens, it is usually a left wing political sentence).
Con Sometimes stop working for few seconds
Sometimes stop working for 10/15 seconds, then starts working again. Inconvenient when looking streaming video on youtube or twitch
Con Icons display blurry on HiDPI
Firefox has not yet addressed its scaling issues for HiDPI screens, making the icons blurry.
Con Uses GTK on Linux/BSD
thus make the integration on non-GTK Desktop Environemnts very hard
Con Poor enterprise support
Does not use standard management tools such as GPO or Profile management. No MSI.
Con Styles HTML-forms with the OS/Desktop theme
At least on X11/Unix that leads to terrible issues, that makes some websites simply unusable for example: If you use a dark GTK theme that uses white text and come to a webpage that forces black text on html-forms buttons you will get black buttons with unreadable black text.
Con Impossible to launch two separate instances at the same time
E.g. one installed surf-Mozilla and another portable Mozilla for secure browsing (e.g. solely used for internet banking). One first has to close one to open the other.
Con Updates not in sync with updates of (key) extensions
A key extension can suddenly becomes useless because extension updates tend to fall behind the updates of Firefox.