Open Source

Sheet Geek

Your AI can read your spreadsheet. Then it guesses what the numbers mean.

Sheet Geek is a free, open-source skill that cuts the guessing. It reads the file first, asks you only what the data can't tell it, and saves what you told it inside the file, where any AI that reads the file's tabs can find it.

Bring us the bottleneck
Chalk stick figure in round glasses with its arms crossed and a pink brain on top of its head

The rules that make a spreadsheet right usually live in one person's head. Which rows are refunds. Which raise hasn't closed. Which two customers are really one. Sheet Geek writes them into a tab called _brain, so your accountant's AI, your investor's AI and your own next chat all start from what you said.

How It Works

It reads everything first
Every row, with code. It finds the tables, the keys, which columns match across tabs and files, what each formula feeds, and anything odd.
It asks a handful of questions, not thirty
Only what code can't know: your goal, what a number really means, what to leave out, and whether the data is complete. Each question carries its reason and, when the data supports one, a recommended answer.
It writes the brain into the file
A _brain tab (for a CSV, a .brain.json file next to it): what each column means, how things connect, what you said and what code counted, each note labeled and dated. Your data cells are never changed.
It draws the map
A clickable graph of what connects to what, in one offline HTML file.
It stays current
Open the file next month and it says what changed and which notes might be out of date.

Install

Claude Code: run /plugin marketplace add Actual-Intelligence-Labs/sheet-geek#release, then /plugin install sheet-geek@sheet-geek.

claude.ai and ChatGPT (Work mode): download sheet-geek.zip from the GitHub releases and upload it as a skill. In ChatGPT you can also attach your spreadsheet in a Work chat and paste the repository link.

Codex, Cursor, VS Code, Gemini CLI and other Agent Skills tools: copy the skills/sheet-geek folder (from the repository or sheet-geek.zip) into the tool's skills folder, and add the snippet for your tool from adapters.

Then say: "Give this spreadsheet a brain." It needs Python 3.10 or later with the openpyxl package (CSV files need only Python), and works offline.

Tested Before Release

We froze the tool, then tested it on twelve synthetic businesses built after the freeze, with AI agents playing the owners and two blind AI judges from two labs. With the brain, answers scored 10.3 of 15 against 5.3 without, higher on all twelve. Exact answers went from about one in ten to six in ten. The gain came from the larger models; Claude Haiku 4.5 gained nothing. Read how the experiment was run.

Your Data

Sheet Geek runs inside your AI app or on your computer. Its code makes no network calls and has no tracking, and we never receive your spreadsheets, your answers or the brain it writes. Sentences it flags as private, like one marked "between us", stay on your machine. It misses many others, so read the preview before you save a brain into a file you will share.

The details are in the Sheet Geek privacy policy and the terms of service.

Support

Email interested@actualintelligencelabs.ai or open an issue on GitHub. Include the message you saw and which AI app you used. If a file is needed, send one with fake data, never a real spreadsheet with private information.

Common fixes (a file open in Excel, a password-protected file, a missing package, the map not opening) are in the README troubleshooting list.

Security problems: email interested@actualintelligencelabs.ai with "Sheet Geek security" in the subject, not a public GitHub issue. Details are in the repository's security policy.

Common Questions

Is Sheet Geek free?
Yes. It is open source under the Apache 2.0 license, free for personal and commercial use.
Does Sheet Geek change my data?
No. It never changes a cell. It adds one tab (for a CSV, a separate file next to it) and checks that every sheet of your data stays byte for byte the same. A visible brain becomes the tab the file opens on, and removing the brain puts the file back exactly as it was. In ChatGPT it saves the brain into a copy you download.
Which AI apps does it work with?
We have tested it in Claude Code and in ChatGPT's Work mode. It uses the open Agent Skills format, so claude.ai, Codex, Cursor, VS Code and Gemini CLI should work too. Any AI that can read a spreadsheet tab can read a brain.
Can other people read the brain?
Yes. Anyone with the file can read the tab, and a hidden tab is not private. Sentences Sheet Geek flags as private, like one marked "between us", stay on your machine, and so do business terms like contract prices unless you choose to include them. Other remarks and names from your data can end up in the tab, such as a column of customers or the customer with the largest total, so check the preview, or send a copy without the brain.
Who makes Sheet Geek?
Actual Intelligence Labs, an AI research and implementation lab in Sarasota, Florida. Each brain it writes says so in one line. It is not made or endorsed by OpenAI, Anthropic or any other AI provider.

Keep Exploring

The Sheet Geek Experiment

Twelve businesses, a frozen tool and two blind judges: how we tested whether a brain tab helps.

Read more →

Context Engineering

A model only knows what it can see. The brain tab puts the owner's rules where the AI looks.

Read more →

Operations Intelligence

Systems that read the spreadsheets, PDFs and tools a business already runs on.

Read more →
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