Opera is available on Windows, macOS, Linux, Android, and iOS (Safari WebKit engine).

[19] Opera was released on Monday, April 10, 1995, making it one of the oldest desktop web browsers to exist.

[22] In 1994, Jon Stephenson von Tetzchner and Geir Ivarsøy started developing the Opera web browser while working at Telenor, a Norwegian telecommunications company.

With version 8.5, released in 2005, the ads were completely removed, and the browser's primary financial support came through revenue from Google (by contract, Opera's default search engine).

[31] Among new features introduced in version 9.1, released in 2006, was fraud protection using technology from GeoTrust, a digital certificate provider, and PhishTank, an organization that tracks known phishing web sites.

[32] This feature was further expanded in version 9.5, when GeoTrust was replaced with Netcraft, and malware protection from Haute Secure was added.

[44] On 12 February 2013, Opera Software announced that it would drop its own Presto layout engine in favor of WebKit as implemented by Google's Chrome browser, using code from the Chromium project.

[45] On 3 April 2013, Google announced it would fork components from WebKit to form a new layout engine, Blink.

[52][53] In January 2017, the source code of Opera 12.15, one of the last few versions still based on the Presto layout engine, was leaked.

PC World compared it to demo models that automakers and hardware vendors release to show their visions of the future.

Instead of a Speed Dial Browsing feature it displays the frequently accessed websites in resemblance to a desktop with computer icons scattered over it in an artistic formation.

This version, inspired by the previous Opera Neon design, was called "Opera Reborn" and which redoes parts of the user interface, such as adding light and dark modes, and integrates the messenger applications Facebook Messenger, WhatsApp, and Telegram.

The "Pinboards" feature was also added, letting users create a shareable collection of websites, images, links, and notes in a visual form.

These features include AI Prompts that are suggested to the user, and sidebar access to ChatGPT and ChatSonic.

Major UI changes were made, and a Multithreaded Compositor was introduced, allowing the browser to function and render in animations much smoother than it was previously capable.

[72] Opera's desktop browser includes access to social media messaging apps WhatsApp, Discord, Telegram, Facebook Messenger, X (Formerly Twitter), Instagram, TikTok, and VK.

[78] One security feature is the option to delete private data, such as HTTP cookies, browsing history, items in cache and passwords with the click of a button.

[80] Opera's fraud and malware protection warns the user about suspicious web pages and is enabled by default.

[81] Opera said that this would allow encrypted access to websites otherwise blocked, and provide security on public WiFi networks.

GX Cleaner is a tool that is said to allow users to clear cache, cookies, and other unwanted files etc.

The browser also has a built-in page called the GX Corner, which combines gaming-related releases, deals, and news articles.

New features are first introduced in the developer build, then, depending on user feedback, may progress to the beta version and eventually be released.

[111] The beta stream, formerly known as "Opera Next", is a feature complete package, allowing stability and quality to mature before the final release.

[120] Versions with the Presto layout engine have been positively reviewed,[123][124][125] although they have been criticized for website compatibility issues.

[126][127] Because of this issue, Opera 8.01 and higher had included workarounds to help certain popular but problematic web sites display properly.

[130][131][132][133] Despite that, versions with the Blink layout engine have been noted for being fast and stable, for handling the latest web standards and for having a better website compatibility and a modern-style user interface.