Open-source Opera alternatives

Zen is a web browser built on Firefox, with the stated aim of taking productivity to a new level. Its tagline invites users to a calmer internet. The source is developed in the open on GitHub under the MPL-2.0 license, and GitHub reports C++ as its main language.

Zen is published in two update channels. The Release channel follows stable builds, and the Twilight channel follows release candidates, and both are built against a specific Firefox version listed in the README. The project provides downloads, documentation and release notes on its website.

Bug reports go to the GitHub issue tracker and feature requests to GitHub Discussions, and contributors are asked to read the contribution guidelines first. Because it builds on Firefox, it suits people who want the Firefox engine with a different interface and workflow focus. The repository also lists partner organizations that support the project.

Brave is a web browser built on Chromium and available for Android, iOS, Linux, macOS and Windows. This GitHub repository is not needed to build the browser: it holds only issues, releases and the wiki, while the source code and contributions live in the brave-core repository. Brave is released under the MPL-2.0 license, and the browser is also known for including ad and tracker blocking by default.

The repository's wiki provides documentation for developers, administrators and power users, and the Brave help center covers user-facing questions. A release schedule explains how versions are published, and a security policy describes how to report problems. The community has a Q&A forum, a guest channel on Slack and a Transifex project where people can contribute translations. The latest stable release is available from the Brave website.

Firefox is a web browser built by the non-profit Mozilla organization, and this is its official source repository. The project describes the browser as fast, reliable and private, and it competes with browsers from commercial vendors by being developed in the open under an organization that is not a company.

The repository is the starting point for contributors. Mozilla points developers to a Quick Reference for contributors, to the Firefox Source Docs as the primary documentation, and to Firefox Nightly for development builds. Bugs are filed on bugzilla.mozilla.org rather than in GitHub issues, and developer questions are handled on Matrix at chat.mozilla.org.

Most of the source is JavaScript, alongside lower-level code, and the code is distributed under Mozilla's open-source licenses, mainly the Mozilla Public License. Anyone can read and build the code, track development, or contribute fixes by following the documented workflow, while end users normally install released builds from the Firefox website.

Floorp is a free and open-source web browser based on Mozilla Firefox. The project describes its mission as keeping an open, private and sustainable web alive, and it builds on Firefox's Gecko engine for rendering pages.

The repository holds the source code for Floorp 12 and is written mostly in TypeScript. The project provides an official site with downloads, a blog with release notes, a Discord server and documentation. It is funded through sponsorship, including GitHub Sponsors, which helps cover development and server costs, and several companies are named as special sponsors.

Floorp is released under the MPL-2.0 licence, the same licence family used by Firefox. As a browser it is installed as a desktop application from the official download page, and the README lists the supported operating systems and getting-started steps for users.

Waterfox is a customizable web browser based on Mozilla Firefox. The official repository holds Mozilla platform code together with Waterfox's own product code, branding, features and packaging, plus release files, and it is built with the Mozilla build system using the usual mach entry points.

According to the project website, Waterfox focuses on privacy out of the box and on customization. It includes built-in ad blocking, private and anonymized DNS, and no telemetry or data collection, along with a variety of quality-of-life features. The site shows an interactive preview where you can choose a browser design, a color palette, light or dark mode and horizontal or vertical tabs, and offers downloads for Android, Linux, macOS and Windows.

Waterfox is free and open source, and development is supported by donations. Most Firefox development documentation still applies to its source tree, and the project provides a blog, changelog, help center and community channels.