tandem

An editor where you and an AI work on the same document at the same time.

Tandem is a document editor that lets you and an AI work on the same file together. You highlight a passage. The AI sees what you highlighted and can ask about it, comment on it, or propose changes that appear as cards beside your document. You decide what to keep.

One thing to know up front: the AI side requires an MCP-capable AI client — Claude Code is the default — and the subscription behind it (for Claude, a paid Anthropic plan). Without one connected, Tandem is a capable local document editor and nothing more.

Tandem is approaching v1.0 and ships continuous improvements. See CHANGELOG.md for what is in the latest release.

Contents

• What Tandem does
• See it in action
• Who Tandem is for
• Getting started
• How you work with Tandem
• Privacy and trust
• Where Tandem is headed
• Documentation
• License
• For developers and contributors
  • Architecture overview
  • The MCP integration policy
  • MCP tools at a glance
  • Channel push and real-time updates
  • Development setup
  • Tech stack
  • How to contribute

What Tandem does

Most people use AI on a document by copying a passage into a chat window, asking a question, and pasting the answer back. Tandem closes that loop. The AI sits beside the document you are editing and reads from it directly.

When you highlight text, the AI sees the selection as you make it. You can ask it for a rewrite, a summary, a check on tone, or a second opinion. Its suggestions appear as cards next to the document. Accept them, reject them, or reply to ask for something different.

Tandem is built to work with Anthropic's Claude out of the box. Other AI tools can also connect. See the developer section below for the details of which clients work and which are tested first.

See it in action

The main view. Your document fills the left side. The side panel on the right holds the AI's annotations and the chat conversation.

Annotations from the AI. Comments and suggestions appear as cards. For a replacement, your current text and the proposed wording show together — accept the change, reject it, or reply to ask for something different.

The chat panel. Ask a question about the document and the AI answers in place — it can read the file directly, so there is nothing to copy and paste.

Several documents open in tabs, with the formatting toolbar above the text. Highlight a passage and the AI sees the selection as you make it. The Solo / Tandem toggle on the right controls whether the AI's annotations appear live or wait until you are ready.

Who Tandem is for

• If you draft long-form writing and want a second reader for tone and structure.
• If you review documents — an essay, a thesis chapter, a report, or a contract — and want a faster pass.
• When a colleague hands you a document to mark up.
• When the AI wrote a draft and you need to decide what to keep.