Independent software

Software that works for you, on your own computer.

GS VectorShell is an independent software maker. Our first product is Twinmark, a markdown editor for Windows. More are on the way.

Products

One so far, with more in the works.

Available now · Windows 10 and 11

A markdown editor with the markdown source and the finished page side by side, kept in step as you type in either one.

Checks for broken links, structure, accessibility, and markdown that won't look the same on GitLab and GitHub
An optional AI assistant that can run on your own computer, and asks before it changes anything
Version history, crash recovery, and export to HTML, PDF and Word

We're working on what comes next. When there's something to show, it will be here.

A few things we hold to, whatever the product.

Our apps do their work on your own machine. Nothing you make is uploaded anywhere unless you choose to send it.

You don't sign up for anything, and nothing watches how you use the app. This website has no cookies, analytics or scripts either.

We build on plain, open formats, so what you make opens in other tools too. You're never locked in.

Need help with Twinmark, have an idea, or want to talk about something else? There's a way to reach us for each.