When comparing Mozilla Firefox vs Vivaldi, the Slant community recommends Mozilla Firefox for most people. In the question“What are the best desktop web browsers?” Mozilla Firefox is ranked 1st while Vivaldi is ranked 3rd. The most important reason people chose Mozilla Firefox is:
Firefox [scores strongly on HTML5 feature support](http://html5test.com/results/desktop.html).
Ranked in these QuestionsQuestion Ranking
Pro Strong HTML5 feature support
Pro Free, open source and community driven
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.
Pro Syncs between devices
Firefox Sync is an optional feature in Firefox that allows syncing bookmarks, passwords, and add-ons between devices.
Pro Strong developer tool
The built-in developer tools have been merged with the popular FireBug extension since FF57
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 Automatically updated
Firefox is automatically updated on the platforms where it makes sense.
Pro Awesome customizability
Pro Good font rasterizing
Font rasterizing on Windows is much better than in competitors. Even smaller text is clear and contrast.
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 Uses less resources
Firefox 57 (Quantum) and newer uses less resources than ever. It is proven with benchmark done by AppleInsider.
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 High performance
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.
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 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.
Pro Integration with Pocket
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.
Pro Android version allows installation of addons
Pro Tabs can be stacked
Tabs can be grouped under a single tab to easily keep track of all open webpages.
Pro Compatible with most Chrome extensions
Since Vivaldi is built on Chromium, the same base as Chrome (among other browsers) is built on, it was possible for Vivaldi developers to allow Chrome extensions to run in their browser.
Pro Built for power users
Vivaldi includes lots of niche functionality such as the ability to move tabs to any side of the screen, turn images on and off, or render pages with monospace fonts.
Pro Full of customizable keyboard shortcuts (can be completely keyboard-driven)
It's possible to change and add keyboard shortcuts for basically all commands. It also has single key shortcuts to execute actions with one click.
Pro Ability to search through settings, history, open tabs, bookmarks in one place
A feature called Quick Commands (accessed via Ctrl + Q) allows quickly getting to settings, history, open tabs, bookmarks with incremental search.
Vivaldi is available on Windows, Linux and OSX.
Pro The UI can be customized with ease
Pro Web Panels
Web Panels allow for easy access to any site from the side panel. They are useful for reading two websites side by side or for chatting (i.e. Facebook) and surfing at the same time. Panels can be hidden when not in use.
Pro Mouse gestures
Integrated mouse gestures. Fully configurable as of Vivaldi 1.2 (snapshot available now). Allows for navigating the web, switching tabs, closing windows, opening settings etc. with a flick of the mouse.
A notes panel allows leaving notes on webpages and can include screenshots for reference and have tags and organized in folders to help manage them.
Pro Analytical history
View graphically the most visited pages on a monthly, weekly, or daily basis.
Pro Reader mode
Vivaldi has a built-in reader mode so you can remove all the clutter in news pages and read only the content, you can also customise the reader mode, like font size, style and colours.
Pro Cross browser extensions with Opera and Chrome, Firefox web-ext's too
All Vivaldi, Opera and Chrome users can get extensions from all extension/addon sites, especially from Opera Addons and Chrome Store.
Pro Tab behaviour can be customised
The order you toggle, open, close or clone tabs can be modified to match a workflow that best works for you. For example you can choose tabs to toggle in recent order so you can go back and forth between the last most useful tabs without needing to change their position on the tab bar.
Pro Built-in page capture
Vivaldi can grab a picture of the whole webpage or part of it and saves it automatically inside a note or as a file in your disk.
Pro Non-closable fixed tabs
A setting lets you prevent closing fixed tabs so you don't close anything important by accident.
Pro Custom search engines
You can add as many search engines as you like. For example you can set up one for YouTube, one for Wikipedia, or whatever you want: you need only the URL of the search and it can be used from the URL bar (by prefixing it's nickname,
yt for YouTube for example).
Pro Manage bookmarks very well
Vivaldi has an excellent bookmarks system. Bookmarks can be easily accessible via Speed Dial, side-bar, bookmarks bar, quick commands. No more messy bookmarks bar is needed and location bar suggestion is improved thus!
Pro Sync in beta versions is enabled
Everything can be synced with a Vivaldi account if you are using a snapshot version. Coming soon to stable as well.
Pro Allows navigating to the next page without searching for the link
A feature called fast forward puts a dedicated button before the address bar that is designed to help you navigate to the next page of a multi-page article, forum thread or search results without having to hunt for the link.
Pro Tab bar position can be changed
Users can change tab bar position to top, bottom left or right
Pro WebRTC IP leaking can be disabled
A built-in setting called "Broadcast IP" will stop the IP leaking with WebRTC when disabled.
Pro VPN is available by extension- also routing through Tor network
VPN and Tor encryption is possible through extensions. Tor is a free choice if one doesn't want to subscribe to a VPN service.
Pro Faster than Firefox or Chrome
Pro Faster than Firefox and Safari
Pro Customizable UI
Vivaldi can change the colors across the browser and has the option to change the color automatically depending on the page.
Also, page loading animations are available in the address bar.
Pro Side panel and status bar
Con Doesn't care for its original guidelines/goals
Mozilla originally aimed to be the "good guys" with user choice and privacy in mind. Their current leadership cannot be trusted to hold those goals in high regard:
1) Added Pocket - a privacy data sensitive plugin, made it mandatory
2) Tried to sneak in advertisement as "drive-by hack", backpedaled unconvincingly once users complained: https://www.cnet.com/news/mozilla-backpedals-after-mr-robot-firefox-misstep/
3) Tried to randomly inject a small percentage of Firefox downloads in Germany with a data collecting plugin (Cliqz) that tech-savy Germans consider adware (no opt-out question asked) : https://bugzilla.mozilla.org/show_bug.cgi?id=1406647
Con Uses GTK on Linux/BSD
This makes the integration on non-GTK Desktop Environments very hard.
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 Installs Addons with updates
Mozilla is installing/integrating addons with every update like the Mr. Robot promotion - it also has integrated Pocket that spams you every time you open the browser or a new tab with partners of Pocket.
Con Lack of keyboard shortcuts customization
Keyboard shortcuts can not be changed in a user-friendly way.
It is also difficult to manipulate addons with hotkeys.
Con Gets slower with every extension
Until the 10th extension it works fine but after that it suddenly becomes slower and slower and at some point it takes forever to start - if it starts at all.
Con Poor performance on SSD even without extensions
On a fast SSD such as Corsair Force LE series this browser still performs as if it were installed on a regular hard drive disk, meaning it takes long time to start, even without any extensions. On that matter Google Chrome is light years ahead of Firefox. This applies only for Firefox versions below 60!
Con It's bloated
Just remember that Firefox was created to create a simple and fast browser that would focus on web browsing. However, nowadays Mozilla is adding more and more extensions like pocket or screenshots to the browser(that could easily be done as optional add-ons) that will bloat it just like the old Mozilla Suite (nowadays Seamonkey).
Con Not available on your Phone/Tablet
Vivaldi is currently only available for desktop operating systems (Windows, Linux, Mac). Though the developers have already said that they plan to release it.
Con No automatic page translation
Unlike Chrome, it doesn't automatically translate pages that are not in your language.
Con Comes with many Ads
After installation the first thing you have to do is to remove all the default bookmarks and quickdial links which is really annoying. There is more minor stuff like the default search provider or your start page things that could be easily managed with a wizard at the first startup.
Con Can't protect pinned tabs from changing to another URL
Clicking on a page link, then another, easy to wind up far from the original pinned tab site. There is no chrome addon or native vivaldi function to stop this.
While Vivaldi is currently available gratis (without monetary charge), it is currently not fully libre (meaning that it does not allow users to view the source code used to create, to modify that code, or to redistribute modifications) and is therefore neither free nor open-source software.
The C++ source code however is open-source under a BSD license and can be downloaded and browsed from here.
The UI code though is not open-source, but it's easily readable as it's HTML, CSS & JS. Modifications can be shared as their forum even has a dedicated section.