When comparing Opera vs Chromium, the Slant community recommends Chromium for most people. In the question“What are the best desktop web browsers?” Chromium is ranked 5th while Opera is ranked 8th. The most important reason people chose Chromium is:
Unlike Google Chrome, Chromium is completely open source.
Ranked in these QuestionsQuestion Ranking
Pro Built-In Adblocker
The built-In adblocker is faster than any extension. It's possible to add your own filter lists. However, the adblocker isn't enabled by default.
Pro Video pop-out feature
You can pop-out any video and it will stay on top while you are surfing on other tabs.
Pro VPN onboard
Free and fast VPN onboard, includes Germany, Canada, USA, Netherlands, Singapore.
Pro Compatible with Chrome extensions
Since Opera is built on WebKit, the same engine Chrome (among other browsers) is built on, it was possible for Opera developers to allow Chrome extensions to run in their browser.
Pro Strong HTML5 feature support
Opera scores highly on HTML5 feature support.
Pro Opera Turbo
Opera has a functionality called Turbo which increases browsers speed and reduces data consumption considerably by compressing the data that's found in a web page.
Pro Battery saving mode
Pro Opera Sync
Opera Sync allows you to synchronize your bookmarks, passwords, and more from any computer, phone, or tablet.
Opera is full of user controlled settings. Everything can be imported and exported even RSS feeds. It can be skinned in a variety of different themes or it can be extended through the use of a large number of plugins available.
Pro You can install extensions on the sidebar
Unlike other browsers, you can install add-ons such as tabs, bookmarks, history, sessions, notes, and extension manager in the sidebar. So you have the flexibility to use it for your purpose.
Pro Speed Dial
Opera's Speed Dial (new tab page) has the ability to hold as many websites as you want, and you can customize it almost however you want. You can also organize the websites on the Speed Dial into folders.
Pro For Opera 2017 & 2018 gonna be time of new
Opera got Reborn UI as the first implementation from Opera Neon concept browser. Snap -feature is next. Opera constantly improves its basic functionality - unlike Chrome.
You can save the Opera's setup files on a USB hard drive and run its portable version anywhere.
Pro Opera can have extensions from Opera Addons & Chrome Store websites
Opera supports cross-browser extensions. Opera Addons site keeps quality up compared to Chrome Store. Full of useful extensions, Opera also supports extra APIs like Speed Dial API, Extension Sidebar API and Stash API meaning wider variety of extension possibilities than in Chrome.
Pro Partly open source
Source code available on GitHub.
Pro Blazingly fast
Scores top on Basemark.
Pro Touch bar support
Pro Fast video loading
Opera loads videos faster, making it useful for slow internet connections.
Pro Completely open source
Unlike Google Chrome, Chromium is completely open source.
Pro Supports all of Google Chrome features
As Chrome is based on Chromium they overlap in supported features. Chromium syncs between devices, automatically updates, has great built-in developer tools, installs extensions without a restart, includes a combined text bar for entering URLs and searching and has excellent HTML5 compatibility just like Chrome.
Pro Access to Chrome's extensions
Chromium can access the Chrome Web Store and all the extensions hosted there can be installed and used on Chromium.
Chrome and Chromium are available on almost every device nowadays
Every tab and plugin runs in its own subprocess so they will never affect the whole browser ,however that consumes more memory than other browsers
Pro Backed by Google
Chromium was first released as a large portion of Chrome's source code as an open source project by Google in september 2008. The idea was to encourage developers to review the underlying code and to contribute in making Chrome cross platform and port it to Mac and Linux as well.
Nowadays Chromium is a large project with a huge community that's standing behind it but still Google continues to take an extremely active role in Chromium development. This ensures the longevity and constant development and improvement of the browser.
Con Owned by a Chinese consortium
Who certainly need to conform with Chinese government requirements to let them infiltrate everything you do online.
Con WebKit/Blink is not customisable or lightweight
Opera is built on WebKit/Blink, which means it shares cons of Chromium: high RAM usage (Not lightweight), lack of customizability.
Con Cannot select tabs
Unlike in Chrome and Vivaldi, one cannot select multiple tabs to move to another/new window.
Con Extension icons not directly moveable
Con Uneditable default search providers
It can not delete or replace already built-in search services such as Yahoo, Google, DuckDuckGo, and Wikipedia.
While Opera is currently available gratis (without monetary charge), it is currently not 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 therefor neither free nor open-source software.
Con Fewer extensions
Some buggy or confusing behavior with the bookmarks bar and moving tabs, and entire windows turning black after a while.
Con Basically a Chrome clone
The latest versions of Opera are basically Chrome clones, so they really don't add anything new.
Con No address bar in fullscreen mode
Unlike in Vivaldi.
Con Same security-holes as Chrome
Opera uses the same browser engine as Chrome, meaning it has the same security-holes as Chrome. Chrome is a big target for hackers (being the most popular browser in the world), and a webpage that will hack Chrome will also hack Opera.
Con No reader view
Con No menu bar
Con High RAM usage
Just like Chrome, Chromium also eats a lot of RAM, which can be a problem for machines with smaller RAM.
Con Lacks privacy options
Con Misses some proprietary multimedia codecs
Unlike chrome, Chromium misses proprietary multimedia codecs per default. There might be some ways over ffmpeg and co but it is still a gray zone. Also by enabling, it also removes one of the core features of Chromium of being open source software
Con Lacks support for certain common media formats
As Chromium avoids bundling any proprietary software, media that requires proprietary codecs or formats such as AAC, H.264, MP3 and Flash will not play by default on Chromium.
Con No official builds
There are no official builds available so you have to rely on a third party distributor
Con Not possible to disable WebRTC
Con Can be dangerous
There are plenty of Chromium distributors and every one of them can disable specific features (like sandboxing) for their build, so you will never know what you get.
Con Simple, dull, bare-boned
Con Doesn't read cookies properly
... and for this reason it only remembers the user logins only in the session. Once the browser is restarted for whatever reason, it forgets everything and the user has to login again everywhere which can become annoying very quickly.