Get started with Cellmate
Install the add-on, add your API key, and start writing =cellmate() in Google Sheets.
Getting started
Cellmate is a Google Sheets add-on. A Google Workspace Marketplace listing is coming soon; in the meantime, follow these steps to set it up on your account.
- Open your spreadsheet, then go to Extensions → Add-ons → Cellmate (or install via the setup link we send when you request early access — see Contact).
- Open the Cellmate sidebar from the Extensions menu and accept the requested Google permissions.
- Add at least one API key under Settings → API configs.
- Type
=cellmate(...)in any cell, or run a saved command from the sidebar.
The =cellmate() formula
=CELLMATE(prompt, [value], [configName], [cacheSeconds]) works like any other Sheets function. Pass a prompt and, optionally, a cell or range for context. The result lands in the cell and updates when its inputs change.
=CELLMATE("Summarize this paragraph in one sentence:", A2)=CELLMATE("Classify sentiment as Positive, Negative, or Neutral", B2)=CELLMATE("Extract the company name from", C2:C4)=CELLMATE("Write a tagline", , "My Grok", 3600)By default, Cellmate uses the provider and model you marked as default in API configs. Pass configName to use a different named config. The optional cacheSeconds argument is covered under Formula cache.
Formula cache
Sheets reloads custom formulas often. With cache on (the default), Cellmate reuses a previous result when the prompt and inputs match — so those reloads don't bill your AI provider again.
- Toggle Enable cache in the Cellmate sidebar.
- Turning cache off stops reading and writing the cache; it does not wipe existing entries.
- Start a free trial from the Cellmate sidebar (Sheet owner Google account). Open the sidebar once per spreadsheet so the owner email is saved for
=cellmate(). AI still works when cache is off. - To skip cache for one call, pass
0ascacheSeconds. Example TTL override:=CELLMATE("Write a tagline for an ice cream shop", , , 3600) - Cached entries last up to 30 days (encrypted on Cellmate). For permanent values, paste results as values only.
More detail is in the FAQ → Formula cache.
API configs (BYOK)
Cellmate is bring-your-own-key: you add an API key from an OpenAI-compatible provider in the add-on. Your provider bills you for AI usage separately from Cellmate.
| Field | Description |
|---|---|
| Base URL | The OpenAI-compatible endpoint (OpenAI, Azure OpenAI, Groq, Together AI, Fireworks, OpenRouter, Mistral, or a self-hosted option like Ollama or vLLM). |
| API key | Your key for that provider. Stored in Google User Properties — see Privacy. |
| Model | Default model name, e.g. gpt-4o-mini. Can be overridden per command. |
| Defaults | Optional temperature and max token settings, unless a command sets its own. |
You can add multiple providers, switch the default anytime, or assign a specific provider to a custom command.
Scope + undo
Two safety nets when AI writes to a live spreadsheet:
Scope
Sidebar Run sends the whole Selection, Sheet, or each Workbook sheet as one tableso prompts like "sort by column B" stay coherent. Per-cell work belongs in
=cellmate()formulas instead.Undo
Every command run is one undo step. Click Undo last runin the sidebar, or use Sheets' Ctrl+Z / Cmd+Z.
Custom commands
Save a prompt once and reuse it. A command can include a prompt template, input/output columns, and an optional provider or model.
- Summarize — condense notes into one-line summaries.
- Fix grammar — clean up free-text responses in place.
- Extract line items — pull fields out of pasted invoice text.
- Translate — translate a column into a language you specify.
Commands saved to a spreadsheet are available to anyone who opens Cellmate in that file. Commands saved to your account follow you across spreadsheets.