K-Meleon vs Mozilla Firefox

No malware/adware toolbars/extensions can be injected. You can switch off Java, JS, Flash, popups, and Ads from the toolbar or with a hotkey.

Almost every detail can be personalized:

• skin
• buttons (icon theme and on/off state)
• toolbar placement
• menus
• number of settings and preferences
• proxies (add and switch with ease)
• locale (switch on the fly without downloads and restarts)
  etc.

Light on memory footprint: the smallest RAM amount used among all the modern browsers. Fastest application startup. Very responsive. Invaluable on the older and low-end hardware.

Has hundreds of its native extensions written on its own macrolanguage.
Supports dozens of XPI-extensions for Firefox.

Firefox scores strongly on HTML5 feature support.
Though not as strongly as Chromium/Chrome browsers do.

Firefox Sync is an optional feature in Firefox that allows syncing bookmarks, passwords, and add-ons between devices.

Firefox is available as a free download. All Mozilla software is licensed under the Mozilla Public License. Instructions on how to obtain the source code can be found here.

Mozilla is one of the first browsers that advocates privacy. They believe that internet should be in the user's control and not those who run the websites, and so they give tools inside the browser to make the user be more in control.

The built-in developer tools have been merged with the popular FireBug extension since FF57.

The Firefox Quantum update (FF57) greatly increases the render speed and general performance of the browser, by taking better advantage of the user's hardware.

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).

Firefox uses its own rendering engine (called Gecko), instead of Google-controlled Blink like the vast majority of other browsers.

With new integrations focused on security and performance, Firefox is faster and less likely to have problems during use than ever before.

Open Source means that you can see the source code. So everybody even if they don't work for Mozilla is able to look what the browser does in the background. So you can be 100% sure that Firefox doesn't have hidden "spy features" unlike Google Chrome.

Font rasterizing on Windows is much better than in competitors. Even smaller text is clear and contrast.

Firefox is automatically updated on the platforms where it makes sense.

Firefox 57 (Quantum) and newer uses less resources than ever. It is proven with benchmark done by AppleInsider.

Beyond the toolbar and tabs, it darkens UI elements such as the URL-bar, pop-downs, new-tab page and more.

Great library of add-ons.

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.

It's not dependent on Google.

Powerful screenshot tool built right into the browser.

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).

An enormous number of add-ons.

In order to add an open page to the bookmark bar, the tab can be dragged down and is added immediately.

Blocks tracking cookies, finger print scanners and Cryptominers by default. Can be changed to the user's individual needs.

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.

Firefox Reader Mode includes Narrate, a feature that adds text-to-speech functionality to the browser.

FF experiments are Mozilla projects available from FF Test Pilot, such as Firefox Colour, witch lets you customise your browser theme to your liking!

Helps store your usernames and passwords. Lockwise also lets you know if any of the sites you have login details for have had their (and potentially your) data leaked!

The only web browser that only preloads entire HTML5 video which is useful for slow internet.

Firefox has a solid mobile app.

Firefox comes with built-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.

Many Linux distributions come preinstalled with Mozilla Firefox

Master about:config and uBlock Origin, and all Firefox-based browsers will be yours.

The newer versions of it will soon use WebRender to render webpages, which'll make it much more efficient by utilizing GPU to paint webpages.

UI is better than any other chromium-based browser.