3 free and open-source (FOSS) apps that embarrass Windows' built-in defaults

Published Sep 12, 2026, 7:00 AM EDT Dibakar Ghosh is a tech journalist at How-To Geek, where he focuses on Linux, Windows, and productivity tools. His goal is simple—help readers at every skill level get more done with the tech they use every day. He began his writing career in 2016 with WordPress tutorials, later moving into digital marketing, where he spent years reviewing complex tools for marketers. His work has also appeared on Authority Hacker, where he’s shared in-depth guides on digital workflows and online productivity. That experience now shapes his journalism, blending analytical depth with practical, real-world advice. When he’s not writing or testing software, Dibakar is usually watching movies or playing video games. He’s a huge Christopher Nolan fan and a strong proponent of the theater experience. In gaming, he has sunk hundreds of hours into Insomniac’s Spider-Man series, Returnal, Prototype, Darksiders, and Final Fantasy titles. Most of us put a lot of thought into the big applications we base our workflows around — the video editors, the note-taking apps, the image editors — and almost none into the system-facing apps we use every day. However, those applications make up a huge chunk of our day-to-day experience and deserve more thought than they get. This is especially true right now, as tons of high-quality free and open-source apps have emerged that easily offer a better experience than most of your system defaults. Here are three such FOSS apps to replace your Windows defaults. Komi Store A storefront for GitHub apps If you’re a fan of free, open-source apps — which I’m guessing you are since you’re reading this listicle — you probably spend a lot of time browsing GitHub repositories. Well, Komi Store is here to make your life a whole lot easier. It maintains a catalog of GitHub repos with actual installable binaries and makes them available through an app store-like interface. It has completely changed how I find and install FOSS apps on my Windows PC — offering a similar experience to what you get on Linux or Android. Granted, Microsoft also tried to make the Microsoft Store a thing, but it never really took off, at least not for me. I found it too slow and cluttered with a lot of shady, poor-quality apps. Komi Store offers a much better experience, and the fact that every app is FOSS and sourced directly from GitHub is a huge plus. The app can auto-detect the platform you’re using — it currently supports Windows, Linux, macOS, and Android — and show you a curated list of all supported apps. Alternatively, if you already have an app in mind, you can search for it directly. You can use the app’s real name if you know it, or simply write something like “Notion alternative,” and Komi will give you a list of GitHub apps matching that description. There’s also a Top Charts page that shows a list of trending apps and recent releases. Once you find an app you like, you can click it to open a custom “app page.” It shows the app icon and key GitHub stats, such as star count, forks, pending issues, total downloads, and licensing information. You also get a dropdown to filter through all available versions. However, the main highlight is the Install button. Just one click, and Komi will automatically download and install the app on your system — just like an app store. Download Komi Store. Komi Store doesn't run any security checks on the repositories it makes installable. Practice the same due diligence you would when downloading any app from the internet. Qalculate! Simple by default — serious when you need it to be The default Windows calculator is — fine. It lets you punch in some numbers, offers scientific and programmer modes, and can also function as a converter. However, it overlooks one very basic feature that makes it a complete deal-breaker for a lot of folks, including me. Your calculation history doesn’t persist across sessions and disappears once you close the app. Say I open the app, run a calculation, get my answer, and close it. Two minutes later, I realized I should have multiplied that result by 12 or something. I open the calculator again, and everything's gone. It’s so frustrating that I eventually decided to find a new calculator app and eventually settled on Qalculate! Now, apart from persistent history — which, frankly, is enough for me — Qalculate! is filled with tons of amazing features. The standout feature is its flexible keypad. You can strip it down to a plain numpad with basic arithmetic for quick sums, or switch the keypad to programming or algebra modes. There's even a custom keypad option where you decide how many rows and columns you want and populate the keys with whatever operators you use most. It doesn't get more flexible than that. Beyond the keypad, you also get unit and currency conversion, the ability to define your own functions and variables, and a lot more. It's easily the most feature-packed calculator I've used, but it never feels in-your-face about it — you can make it as simple or as advanced as you want. And this flexibility is what makes it one of the best calculator apps. Download Qalculate! Greenshot The sweet spot between “too basic” and “too much” The default screenshot experience on Windows has been lackluster since time immemorial. Granted, Microsoft has been trying to improve the Snipping Tool on Windows 11, and to be fair, they’ve done a commendable job — but it still falls short compared to the third-party stuff people have been installing for all this time. Now, ShareX is probably the most popular and powerful screenshot app for Windows, and it’s what people have typically defaulted to over the years. But ShareX can be overkill for most users. I believe Microsoft wanted to address that by offering a more lightweight option for casual use — but it feels too casual in my opinion, lacking many of the basic annotation features. This is where Greenshot comes in as the “Goldilocks” screenshot app, offering a decent selection of editing features without making things overwhelming. With a simple keypress, you can quickly capture a screenshot, whether it’s of a selected region, a specific window, or the full screen. After taking the screenshot, Greenshot will immediately drop you into the editing window. From there, you can annotate with various tools, highlight things, and even obfuscate sensitive parts. Once done, you can copy it to the clipboard, save it to your system, attach it to an email, or send it straight into an Office program. It’s really cool, and it’s what I used to capture all the screenshots you’re seeing in this article. Download Greenshot.