February 19, 2026
Pivot-table popcorn, anyone?
Pi for Excel: AI sidebar add-in for Excel, powered by Pi
Open‑source AI sidekick moves into Excel — now everyone’s got opinions
TLDR: An open-source AI sidebar now lives in Excel, helping write, format, and explain your sheets. Commenters love the bring-your-own-AI freedom, but gripe about Microsoft’s sideload/App Store friction, demand a web Excel option for Linux, and ask for a demo — equal parts hype and eye-rolls.
Excel just got an open‑source AI roommate, and the comment section is treating it like a new office hire. “Pi for Excel” is a chatty sidebar that can read your sheets, write formulas, format cells, explain what complicated formulas actually do, and even roll back mistakes with one click. It works with the big AI names you already know — OpenAI, Anthropic, Google Gemini, GitHub Copilot — using your own key or sign‑in. In short: a smart helper that lives inside your spreadsheet.
But the crowd? Split. One camp is cheering the “finally, an open alternative” angle, echoing that there are “about a dozen startups doing this,” so open‑source feels refreshing. Another camp is grumbling about the usual Microsoft roadblocks: a dev ranted that side‑loading add‑ins is “a pain,” and the Office Store is an even bigger headache. Linux users are loud too, begging for a web version of Excel so they can join the party. And several people want receipts — “video or it didn’t happen.”
Meanwhile, a sharp‑eyed commenter noted it’s built on the Pi coding agent and uses a Pi web UI, plus sign‑in tokens (aka logging in with your account) — which surprised folks who assumed it’d be key‑only. The vibes: hopeful, salty, and a little meme‑y. Think “VLOOKUP, meet your intern,” with a side of App Store drama.
Key Points
- •Pi for Excel is an open-source AI sidebar add-in for Microsoft Excel powered by Pi.
- •It supports multiple AI providers (Anthropic, OpenAI, Google Gemini, GitHub Copilot) via API keys or OAuth and allows switching models mid-conversation.
- •The add-in includes 16 tools for reading/writing cells, formatting, tracing dependencies, explaining formulas, and managing workbook structure and history.
- •Features include session management, auto-context injection, workbook recovery checkpoints, formatting conventions, and slash command controls.
- •Extensibility is provided through installable extensions and integrations such as web search (Serper/Tavily/Brave + fetch_page) and an MCP Gateway; experimental bridges include Tmux and Python/LibreOffice.