AI that reads and edits your live Excel workbooks — not just chat, real changes.

Your Excel superpower, inside the spreadsheet you already use.

BuffSheets is an AI assistant built for Excel on Windows. Describe what you want in plain English — add columns, build forecasts, clean data, create charts, structure financial models — and BuffSheets applies changes directly to your open workbook. Review every change before it sticks. Undo when you need to.

Download on Microsoft Store See how it works
  • Free to install
  • Accept / reject every change
  • On-device model option
A1 fx Example Consolidated Balance Sheet

Not another chatbot.

Generic AI tools hand you a formula in a copy-paste box and wish you luck. BuffSheets understands your selection and workbook context, plans structured actions, and executes them through Excel's live engine.

Generic AI chat

  • Dumps formulas into a chat bubble
  • No idea what's in your workbook
  • You copy, paste, fix references, repeat
  • No audit trail, no undo of "its" work

BuffSheets

  • Reads your selection and workbook context
  • Plans discrete, reviewable actions
  • Executes directly in your open workbook
  • Accept, reject, undo — every change logged

Built for people who live in Excel.

Analysts, finance teams, operators, founders — anyone who spends their day in tables, models, and reports.

Actually edits Excel

Not advice — action. BuffSheets writes formulas, adds sheets, builds charts, deduplicates rows, fills blanks, and formats output in the workbook you have open. You stay in Excel; the AI works inside it.

Your choice of AI — private or powerful

On-device models via Ollama keep workbook data on your machine. Hosted cloud models — OpenAI, Anthropic, Google Gemini, xAI Grok — bring frontier reasoning, with a free tier and simple subscription plans. Same Excel engine either way; only the brain changes.

Safety-first by design

Every plan breaks work into discrete changes you can accept or reject. Strict rules guard against destructive edits — no reckless full-sheet wipes, formula-first discipline for financial work. An audit Tabby Log sheet records exactly what was applied.

Skills — teach it your way

Create reusable Skills: Markdown instructions for how you want a task done — "Build a DCF," "Format like our firm's models," "Balance sheet layout." BuffSheets loads the right guidance automatically so outputs match your standards, not generic AI guesses.

Built for financial & analytical work

Strong at tabular reasoning: YoY growth columns, revenue forecasts, assumptions blocks, summary sheets, charts, data cleanup, and structured model layouts — designed with spreadsheet conventions in mind: references, formulas, professional formatting.

Native Excel experience

Lives in a sidebar task pane inside Excel desktop on Windows. No switching apps, no exporting CSVs to a browser tab. Chat, plan, preview, apply — all without leaving the grid.

How it works

Three steps between "I need this" and a finished sheet.

  1. Select & ask

    Highlight a range or work on the whole sheet. Type what you want: "Add a YoY % column with proper formulas" or "Build a conservative 5-year revenue forecast on a new sheet."

  2. Review the plan

    BuffSheets streams its reasoning and shows a structured action plan: what it will change, where, and why. You see previews before anything lands in cells.

  3. Accept, reject, undo

    Approve the changes you want. Reject the rest. Every applied action is logged. If something isn't right, undo and refine your prompt.

Say it like you'd say it to a colleague.

Real prompts, real results — in your open workbook.

"Add a YoY growth % column with proper formulas" "Build me a conservative 5-year revenue forecast on a new sheet" "Clean this data — remove duplicates and fill blanks intelligently" "Create a monthly summary sheet with a bar chart"
"Build a DCF model using our standard layout" "Fix the formulas in this section and highlight errors" "Add an assumptions block above the model" "Summarize variance vs. budget by department"

Finance & FP&A

Models, forecasts, variance analysis, formatted outputs.

Business analysts

Transforms, summaries, charts, repeatable reporting.

Operators & founders

Quick spreadsheet work without hiring a spreadsheet expert.

Power Excel users

AI that respects structure, formulas, and auditability.

Skills: your standards, on autopilot.

Most AI output looks like AI output. Skills fix that. Write a short Markdown file describing how your team builds a DCF, lays out a balance sheet, or formats a board deck export — and BuffSheets loads the right Skill automatically when the task calls for it.

  • Reusable — write once, applied every time the task matches.
  • Plain Markdown — no scripting, no macros, no add-in SDK.
  • Yours — outputs match your firm's conventions, not generic guesses.
build-a-dcf.mdSkill
# Build a DCF

## Layout
- Assumptions block at top, blue inputs
- Years across columns, FY labels in row 3
- FCF build: Revenue → EBITDA → NOPAT → FCF

## Rules
- Formulas only, never hardcoded values
- Terminal value via Gordon growth
- Sensitivity table: WACC × terminal growth

Privacy & models, in plain language.

No vague "enterprise-grade" fluff. Here's exactly what leaves your machine and what doesn't.

On-device mode

Your workbook stays on your computer. Models run locally through Ollama — no cloud provider sees your data. Good for privacy-sensitive work and offline-style workflows.

  • Workbook data never leaves your machine
  • No token charges — bring your own Ollama setup
  • Same Excel engine and safety rules as hosted mode

Hosted mode

Selected workbook context is sent to the model provider you choose — OpenAI, Anthropic, Google Gemini, or xAI Grok. Usage is metered and billed transparently through your plan.

  • You pick the provider; only selected context is sent
  • Request logging (prompt, context, plan, accept/reject feedback) helps improve the product — on by default, opt-out available from your account
  • A one-time disclosure appears before first use of hosted models

Simple pricing, no surprises.

Start free. Upgrade when your workload grows. On-device models are always free.

Free

$0

free forever

  • Free install from Microsoft Store
  • On-device models via Ollama — no token charges, data stays local
  • Starter allowance of hosted-model usage
  • Accept / reject every change, undo, audit log
  • Custom Skills
Most popular

Pro

$20/mo

for everyday spreadsheet work

  • Everything in Free
  • Generous monthly hosted-model allowance
  • All providers — OpenAI, Anthropic, Gemini, Grok
  • Larger workbook context per request
  • Priority support

Max

$100/mo

for power users & finance teams

  • Everything in Pro
  • 5× the Pro usage allowance
  • Optional on-demand spending beyond your plan
  • Early access to new features

All plans include the same Excel engine and safety rules. Manage billing from in-app account settings.

Frequently asked questions

Does BuffSheets work in Excel Online or Mac?

Currently optimized for Excel desktop on Windows. Check the Store listing for the latest platform support.

Will it overwrite my data without asking?

No. Changes are planned, previewed, and applied as discrete actions you can accept or reject. Undo is supported.

Do I need an account?

On-device models can run locally. Hosted cloud models require sign-in; the free tier includes a starter allowance, and Pro or Max plans cover heavier use.

Is my data used to train AI?

Hosted requests may be logged to improve BuffSheets (prompt, context, plan, feedback). You can opt out in account settings.

How is this different from Copilot in Excel?

BuffSheets is purpose-built for structured, formula-aware edits with Skills, per-change control, an on-device option, and multi-provider model choice — tuned for analytical and financial spreadsheet work.

What do I need for on-device mode?

A local Python server and Ollama, documented in the install guide for developers and power users. Hosted mode needs nothing beyond sign-in.

Stop copy-pasting formulas out of a chat window.

Get AI that works where you work — with review, undo, and an audit trail.

Get BuffSheets on Microsoft Store

Free to install · Excel desktop on Windows