Get Tandem
Free to download and runs on your machine. Pick your platform and open a file — you can be writing together in under a minute.
Latest release
Connect Claude
Three steps to a co-author
Tandem talks to Claude through MCP. If you've set up an MCP client before, this will feel familiar.
Open Tandem and a file
Drop in any Markdown, text, HTML, or Word document — or start a fresh one.
Point it at Claude
In Settings, add your Claude endpoint under AI Assistant. The status pill turns green when the connection is live.
Highlight something
Select a line and ask. Claude's first note shows up in the margin, in coral.
Questions
Good to know
Is it really free?
Yes. The app is free to download and use on your own files. You bring your own Claude access through MCP.
Where do my files go?
Nowhere you don't send them. Tandem is local-first — it reads and writes the files on your disk, and only the text you share with Claude leaves your machine.
Do I need an account?
Not to start writing. You'll need access to Claude to use Tandem mode, but Solo mode works on its own.
What can it open?
Markdown, plain text, HTML, and Word (.docx) files. Word documents get a paged view that looks like the printed page.
Can I turn Claude off?
Any time. Flip to Solo and Claude pauses, holding anything it wanted to say until you switch back to Tandem.