I sometimes get the impression that we have already decided what software is supposed to look like. You download an app. Or, increasingly, you don’t download anything at all and simply open a website. You create an account, log in, store your data somewhere in the cloud and perhaps pay a monthly subscription.
That’s more or less how software works these days. And then something like Capsule (https://withcapsule.app/) comes along. The basic idea is wonderfully simple: What if an app was just a file?
I like that question. Especially because lately I have been experimenting quite a bit with building small tools myself. Not because I suddenly want to become a software developer. I don’t. But vibe coding has made it remarkably easy to turn a small idea into something that actually works.
My recently built Photo Toolkit is a good example. I regularly receive photos that are several megabytes in size, while for a website I often need something closer to 300 kB or less. So I built a little tool that watches my Downloads folder and automatically creates a smaller version whenever a new image appears. That’s it. It solves one very specific problem.
And that is increasingly how I look at software. Instead of searching for one enormous application containing 87 features of which I need three, why not build something small that does exactly what I need? Capsule takes that idea in an interesting direction.
The application is the file
A Capsule is a .capsule file containing the application itself, its interface and its data. The interface can be built using familiar web technologies such as HTML and CSS, while the data can be stored locally using SQLite. Everything travels together.
That means a Capsule behaves almost like a document. You can copy it. Put it on a USB drive. Back it up. Send it to somebody. Move it to another computer. But instead of opening a document and reading some text, you open a small application.
That distinction sounds trivial, but I think it is rather interesting. For decades we have been used to separating applications and documents. LibreOffice Writer is the application; the .odt file is the document. A photo editor is the application; the JPEG is the file. Capsule asks what happens if you bundle those concepts together. The data and the little application needed to work with that data simply become one thing.
This fits remarkably well with vibe coding
This is where things become particularly interesting for me. Vibe coding has changed the economics of tiny software projects. Previously, if I needed a very specific tool, I had roughly three choices. Find something that already exists, use a spreadsheet as a good-enough solution or convince somebody who can actually program to build it. Now there is another option. I can try building it myself.
I have been doing exactly that lately. Small tools, experiments and utilities. Some work surprisingly well. Others mainly teach me something. And that is fine too. But building the application is only part of the story. Suppose I build a little tool for keeping track of interesting websites for Just Me. Perhaps it contains the URL, some tags, a few notes and an indication of whether I have already written about the site.
Technically, building something like that isn’t particularly complicated anymore. But then come all the other questions. Where do I host it? Do I need a database? Do I need a server? How do I deploy updates? Do I need authentication? What if I want to give the tool to somebody else? Suddenly my tiny personal utility has become an IT project.
With the Capsule approach, the answer could simply be: here is the file. That is appealing.
Small software for small problems
There are plenty of things for which I don’t need a platform. A source tracker for an article. A little database of websites. A project log. A reading list. A collection of RSS feeds. A simple research tool. A small inventory. An interactive checklist. Or perhaps some weird little utility that only makes sense to me. Especially that last category is becoming interesting.
Traditional software has to make economic sense. If you are going to spend weeks or months developing an application, you need enough users to justify all that work. Vibe coding changes that calculation. If building something takes an afternoon rather than several weeks, an application with exactly one user can suddenly make perfect sense.
Capsule potentially removes another piece of friction by making distribution ridiculously simple. The application doesn’t necessarily have to become a service. It can simply remain a file. There is AI functionality around this idea as well. You can describe what you want to build and generate a Capsule containing the interface and database structure, and then continue changing it using prompts. That makes the idea even more interesting for people who don’t consider themselves developers.
And it can stay local
There is another aspect that fits rather nicely with the way I increasingly like to use computers. Capsules can work locally. The data lives in the file on your own machine. You don’t need cloud storage simply because somebody decided that every application in 2026 apparently needs cloud storage.
Obviously, sometimes you do want the cloud. If an entire team needs to work with the same information, a single local file probably isn’t going to be the answer. If you need real-time collaboration, central management or access from teni different devices, there are plenty of good reasons to use web applications and cloud services. But sometimes I just want a tool. No account. No login. No subscription. No server. Just open the thing and use it.
Capsule currently provides desktop software for macOS, Windows and Linux, with .deb, .rpm and AppImage packages available. Android and iOS versions are also planned.
It also feels strangely familiar
What I perhaps like most about Capsule is that the whole idea combines something very modern with something almost boringly old. The modern part is obvious: AI-assisted coding, HTML interfaces, SQLite and tiny custom applications created for very specific purposes. The old part is the file. And files are actually rather brilliant. We know what to do with them. You can copy a file. Rename it. Put it in a folder. Back it up. Put it on an external disk. Send it to somebody. Archive it for ten years.
More importantly, there is something very understandable about ownership when it comes to files. If the file is sitting on my laptop, I have it. That sounds ridiculously obvious, but compare it with many modern online services. Your information sits inside somebody else’s database and you are allowed to access it through their application. Usually that works perfectly well.Until it doesn’t.
More experiments, please
I don’t know whether Capsule will become successful. I don’t know whether .capsule files will become something we routinely exchange with each other. And I certainly don’t expect them to replace conventional applications, websites or SaaS platforms. That’s not really the interesting part anyway.
What I like is that somebody looked at the way we currently build and distribute software and asked whether there might be another way. There usually is. And combined with vibe coding, ideas like this could make personal software much more interesting. Not personal software in the sense of software that knows everything about you, but software that you create specifically for yourself.