Omasheet

What Markdown is to text, Omasheet is to numbers.

📄 Text as the source of truth

The spreadsheet becomes a readable, diffable and composable document, not just a binary workbook.

📊 Columns as the computational model

Named, typed data and array expressions connect spreadsheet authoring to dataframe-style transformations.

🔢 Exact arithmetic as a semantic guarantee

Numeric values retain their exact decimal or rational meaning instead of floating-point approximations.

Automatically follows system dark/light mode.

const TaxRate = 20%

sheet Sales

| Month | Revenue | Cost | Profit | Tax | Running |
| ----- | ------- | ---- | ------ | --- | ------- |
| Jan   | 10000   | 6000 | *      | *   | *       |
| Feb   | 12000   | 7000 | *      | *   | *       |
| Mar   | 15000   | 8000 | *      | *   | *       |

Profit  := Revenue - Cost
Tax     := Profit * TaxRate
Running := [Revenue; 0..*].sum()

Install

curl -fsSL https://raw.githubusercontent.com/librasteve/omasheet/main/install.sh | bash

Update: run the same line again. Uninstall: sudo pacman -R omasheet.

Build from source (e.g. on macOS ARM and other Linux): install Qt 6 and Rust (brew install qt rust), then cargo build --release --package omasheet-ui; the binary is at target/release/omasheet.

Building directly from the git repo instead of a local clone needs --locked (cargo install --git https://github.com/librasteve/omasheet --locked omasheet-ui), since omasheet depends on a crate whose compatible releases are all yanked, and only the version pinned in this repo’s Cargo.lock can still be resolved.

Run

omasheet                                # the app, on a new file
omasheet examples/budget.omx            # the app, on a .omx, .csv, .json or .xlsx file
omasheet print examples/budget.omx      # print the calculated file
omasheet eval '1/3 + 1/6'               # 0.5, exactly
omasheet export examples/budget.omx --xlsx [or --csv | --json]
omasheet render examples/report.md --html

AI Skill

Prompt your favorite AI with:

Please load the Omasheet skill from https://raw.githubusercontent.com/librasteve/omasheet/main/.claude/skills/omasheet/SKILL.md and follow its instructions when creating, checking, or converting spreadsheets.

Docs

The file format
Expressions
The app and the command line
XLSX, CSV, JSON and Markdown
examples/ — worked files, each with its expected output
openspec/ — the design and the specs

Early and changing. MAY CONTAIN ERRORS.