Show HN: Capsule – Single-file web apps that save their data into SQLite

Post by MattCruikshank » Wed, Sep 16, 2026, 3:39 PM UTC

zhynn wrote: post #165

MattCruikshank wrote: post #162

Neat! Another way to achieve something like this is Cosmopolitan C Compiler, Actually Portable Executables. For example, Redbean. (Jart, all of your certs are bad! I can't open your websites any more!) http://justine.lol/ It's a binary that can run on Windows, Mac, Linux, and it is also a zip file. The application can read the zip file and on several systems (not Windows), it can self-modify the zip file. Including h…

I have been meaning to use Justine's RedBean to build a "project app" (kind of like what the OP describes, but leaning more towards something like Datasette). It would contain the data, the paper(s), and the UI for interacting with the data (and supporting scripts or R that can be run with other tools). I just like the idea of a portable single-file scientific artifact. (also another call for jart to fix their certs!…

Post by cosmic_cheese » Wed, Sep 16, 2026, 4:01 PM UTC

rtvn83 wrote: post #159

mg wrote: post #60

> but trying to save data required hosting it somewhere With the File System Access API, webpages nowadays can read and write local files just like desktop applications: https://developer.chrome.com/docs/capabilities/web-apis/file... Try this text editor for example: https://googlechromelabs.github.io/text-editor/ It works nicely on Desktop and Mobile.

it's not only about saving data but easily sharing too. I think the capsule file is great for sharing one's work without the hassle of hosting.

Post by tbrockman » Thu, Sep 17, 2026, 1:47 AM UTC

bithammerthunde wrote: post #149

tbrockman wrote: post #102

Earlier quoted context omitted.

It's not using the File System Access API, on Firefox it uses for file-picking, and the save just downloads it. It's not synchronizing anything with your filesystem.

Do you know the reason for that? The File System API does seem to be well supported on Firefox: https://developer.mozilla.org/en-US/docs/Web/API/File_System...

Post by srikanthkasa » Thu, Sep 17, 2026, 6:43 AM UTC

bashtian wrote: post #69

razerbeans wrote: post #37

I love this idea! One of the fallouts from widespread AI adoption that I've seen: They're very good at creating visual artifacts, but if you ever have to provide data in those artifacts, you don't really have a great way to share it without hard coding it. > One downside with this approach is that multiple people working on it will create different copies. To make it possible to merge different copies of the same fil…

Each document record is saved with UUID and timestamps. When deleting a record the data is removed but the record keeps a tombstone so only the ID remains. For conflicts currently the newest one is used, but there will be a merge like UI in the future to confirm which one to use.