The Best Open-Source Apps Everyone Should Know

Drag almost any video onto it and it starts: the product page promises MPEG-2, H.264, MKV, WebM, WMV and MP3 among the formats it handles with no codec packs needed. VideoLAN, the organization that publishes it, releases the player under the GNU General Public License Version 2. MKV playback with no codec packs is the thing that ended an entire era of hunting for codec bundles.

Mozilla ships the binaries under the Mozilla Public License, and its own licensing page says executable software released by the Mozilla Project, naming this browser and Thunderbird, comes under the MPL. Tracker blocking is switched on from first launch rather than buried three menus deep. Keep it installed even as a second browser, because the alternative is a web where one rendering engine quietly decides what works.

Documents saved here land in the Open Document Format, which the project describes as a fully open and ISO standardized file format that guarantees access to your data forever. That is the part that matters the day you need a file from 2009. The suite itself is published under the Mozilla Public License v2.0. Layout of heavily formatted pages is not Word's, and by the second page you stop noticing.

License detail that actually matters here: the license file names the GNU LGPL for most of the code, but the unRAR portion carries a restriction, in that those sources cannot be used to re-create the RAR compression algorithm. So this is not one clean license across the whole program. What you get is an archiver that opens practically everything anyone emails you, and a 7z format with LZMA2 compression.

Messaging your relatives can be talked into, which is the only test encryption software ever really faces. The site describes state-of-the-art end-to-end encryption powered by the open source Signal Protocol, and the Android client's repository carries an AGPL-3.0 license. Everything else on this list you install for yourself; this one only pays off if you can drag other people onto it too.

Email clients went out of fashion, then webmail got heavy, and here we are again. Messages, calendars and contacts sit in one app, with a unified inbox across accounts so you stop hopping between four browser tabs. Its own about page places the project inside MZLA Technologies Corporation, a wholly owned subsidiary of the not-for-profit Mozilla.org, and Mozilla's licensing page puts the binaries under the MPL.

Photoshop's shape without Photoshop's rent, and the learning curve is real, so give it a weekend before the toolbox stops feeling hostile. The features page names a perspective clone tool, which clones along a plane you define instead of flat across the image, and that one thing rescues a lot of architectural photos. Its source repository lists the license as GPL-3.0.

Recording a podcast, ripping old tape, tidying a lecture: this is the wave editor people land on. Be precise about who runs it, though. The site's footer reads Muse Group & contributors and names MuseHub as the official distributor, so it is corporate-stewarded open source rather than a volunteer project. The source repository lists a GPLv3 license. The interface has looked the same for years and that turns out to help.

Video files that are too big or in the wrong wrapper are a solved problem, and this is the thing that solves them. Its features page names AV1, H.265 and H.264 among the video encoders, so H.265 encoding is one preset click away. The repository lists the license as GPL-2.0. Let the presets do the thinking and ignore the advanced tab until something actually goes wrong.

Library management for e-books, and the part most people miss is the built-in EPUB editor. The site calls it the builtin e-book editor and says it edits EPUB and Kindle books, so a broken table of contents is yours to fix. The source repository lists GPL-3.0. The interface is dense and old-fashioned, and it has never once mangled a file on me.

Streaming and screen recording went one way and never came back, and the reason is structural. Scenes built from multiple sources are the core idea: window captures, images, text, webcams and capture cards, layered and switched on a hotkey. The repository lists the license as GPL-2.0. Setting it up costs an evening; after that you stop thinking about it and just hit record.

Torrent clients used to be a minefield of bundled toolbars, and this one's feature list says No Ads. A built-in search engine sits inside the client, extensible with plugins, next to RSS feeds with regex download filters. The COPYING file states the source is under the GNU General Public License, version 2 or at your option any later version. What you fetch with it is your business, and the client itself is clean.

Dropbox without the Dropbox: folders sync straight between machines you own, and the project states that none of your data is ever stored anywhere else other than on your computers. The MPL-2.0 license is declared on its repository. Pairing device IDs is fiddlier than a cloud login, and then it runs quietly for months. Best for anyone who wants a laptop and a desktop to agree.

Vector drawing for people who are never going to buy Illustrator: logos, cutting files, diagrams, posters. The about page calls it a free and open source vector graphics editor, names the SVG file format, and lists SVG, AI, EPS, PDF, PS and PNG among the formats it handles. The project wiki gives the license as the GNU General Public License, Version 2 or Later.

Digital painting rather than photo editing, and the difference shows up immediately in the toolset. The features page names a Color Smudge engine among its brush engines and describes more than one way to smooth and stabilize a stroke, which is what lets a mouse-drawn line survive. Source repository lists GPL-3.0. Tablet owners get the most from it, everyone else still gets a serious painter.

Timeline video editing with no subscription attached, and it is honest about its plumbing: the project says most of the video processing is done by the MLT Framework, which leans on FFmpeg and frei0r underneath. Proxy clips are generated as low-resolution copies so an ageing laptop can cut the edit and render at full resolution afterwards. Repository license: GPL-3.0.

Modeling, sculpting, rigging, animation and compositing in one program, given away, and the license page states it is released under the GNU General Public License. The Cycles render engine is the built-in unbiased path tracer, and it is the reason studios stopped filing this under cheap alternative. It's steep, genuinely steep, and what you get at the end is a pipeline nobody invoices you for.

Smart-home software that runs on hardware you own, described on its front page as open source home automation that puts local control and privacy first, with Zigbee, Thread, Z-Wave and Matter named across its integrations and its own hardware. The core repository lists an Apache 2.0 license. There is a commercial arm: Home Assistant Cloud is an optional subscription from partner Nabu Casa, which the site says helps fund development.