Using Multiple AI Assistants with InDesign

The short answer: Yes, you can use Sidekick in more than one AI assistant, even at the same time. They all work in the same InDesign.

Setting it up

You need the InDesign plugin once. One subscription covers every assistant on your computer.

Then pick one way of installing Sidekick for the whole computer, and add it to each assistant:

• Most people: the installer. Install Sidekick once from the install page, then follow the guide for each assistant, such as ChatGPT, Cursor or Claude Code. They all use the same indesign-sidekick start command. There is nothing extra to install per assistant.
• Already use Node.js? Use the npx route in every assistant instead (the npx tab in each guide). Nothing to install at all, and each assistant gets the latest version when it starts.
• Claude Desktop and Cowork: keep the one-click Claude extension. It is self-contained and works fine next to the installer or npx in your other assistants.

Add Sidekick only once per assistant. If an assistant has Sidekick twice, it starts two copies and every tool shows up twice. The usual way this happens is in Claude Desktop: the Mac installer asks “Register Sidekick with Claude Desktop?”. If you already use the Claude extension, or plan to, click No. Already said yes? Open Claude’s Settings → Developer → Edit Config and remove the indesign-sidekick entry, then restart Claude.

To check each assistant, ask it sidekick health with InDesign open.

How it works

When you start your first AI assistant, its copy of Sidekick becomes the “primary” — it opens the connection to InDesign. Any additional assistants you start afterward connect through that primary.

From InDesign’s perspective, there’s just one connection. From yours, each assistant can send commands independently. All assistants share the same InDesign instance — whatever documents are open, the selection state, the current view. Sidekick queues all requests and executes them one at a time, so commands never collide or step on each other.

No configuration is needed. It just works.

Common scenarios

Claude Desktop for conversation, Claude Code for automation. Use Claude Desktop for exploratory work — describing what you want, iterating on a layout — while Claude Code handles repetitive scripting tasks or batch operations in the background.

A chat assistant and a coding assistant. Ask ChatGPT or Claude to restyle a spread while Cursor or Claude Code builds a script that fills a catalogue. Keep in mind that they share one InDesign: if one assistant opens a different document, the other sees that change too.

Testing different models side by side. If you’re curious how different AI assistants approach the same task, you can run them simultaneously and compare their solutions.

What you’ll see

The Sidekick panel in InDesign shows “Connected” regardless of how many assistants are connected. Each assistant’s requests appear in InDesign as they execute — you’ll see the application respond in real time.

Potential issues

Commands are sequential. Because requests queue up and execute one at a time, two rapid-fire commands from different assistants won’t run in parallel. They’ll run in order, which might occasionally create a brief wait.

Primary assistant quits. If the assistant that opened the primary connection quits, the others will briefly disconnect while one of them takes over as the new primary. Reconnection is automatic — you might notice a pause of a second or two.

Port conflicts. In rare cases, another application might be using port 6001. See When your AI Assistant isn’t responding for troubleshooting steps.

Questions?

Reach us at [email protected].