Headless Spreadsheet Engine

Formulon

Name: Formulon
Author: libraz

A workbook calculation platform for apps, automation, and AI agents.

Formulon ships one C++17 calculation core across WASM, Python, Native Node, CLI, and MCP so applications can read, evaluate, recalculate, and write .xlsx / .xlsb files without Excel, Microsoft runtimes, or COM automation. For a spreadsheet UI in the browser, formulon-cell builds on the same engine.

Quick Start Why Formulon

Try the live demos Browse scenarios

v0.18.0: Documentation target
511 / 526: Local / recognized functions
47: MCP tools

The remaining 15 require external services such as Copilot, cloud Python, image fetch, market data, or CUBE connections. See why

Operations

Start from the job.

Formulon is easiest to evaluate from the place where the workbook runs. Pick the deployment first, then move into the runtime, API, and compatibility details that matter for that path.

DeskUpload workbook in a browserWASM loads workbook files, edits formulas, and recalculates in the browser without an Office runtime.BackendRecalculate inside a Node serviceAccept .xlsx files in an upload API or internal service, then recalculate with Native Node or WASM.BatchBatch recalculation from PythonRecalculate workbooks in report generation, ETL pipelines, and scheduled jobs.PipelineWorkbook regression in CIDetect calculation changes by comparing checked-in formula and value snapshots.AgentEdit workbooks from an AI agentUse MCP tools to open .xlsx or .xlsb files, mutate cells, sheets, names, and layout, then recalculate.UIEmbed a spreadsheet UI in a web appPut a grid with formula bar and ribbon in your page through formulon-cell, with React and Vue adapters. Beta.

MCPWorkbook operation tools for AI agents RuntimeWASM, Python, Native Node, and CLI share one C++17 core Use casesBrowser upload, Python batch, and CI workbook regression WorkbookDynamic arrays, PivotTables, structural edits, iterative calculation CompatibilityFunction availability and Excel oracle data

Why Formulon

Excel's answers, without running Excel.

Workbooks are calculated inside your own process, with no desktop app to automate and no hosted service to send files to. How closely the results match Excel is measured and published.

OracleChecked against real Excel

Results are compared with values captured from Excel 365; each known difference is recorded with its reason and build.

Locale28 locale profiles

Fourteen locales on Mac and Windows, so text comparison and formula names follow the Excel you target.

LocalData stays with you

Calculation is local. In a browser, an uploaded workbook never has to leave the device.

One coreSame value on every runtime

WASM, Python, Native Node, CLI, and MCP all call the same C++17 core.

Round tripLoad to save, not just formulas

Open .xlsx or .xlsb, edit, recalculate, and write the workbook back.

Coverage511 of 526 functions run locally

The other 15 depend on Microsoft 365 services and return a fixed error.

Compare with Excel, office suites, formula libraries, and cloud APIs

Live Workbook

Try functions through npm formulon

This sheet is the real formulon-cell surface backed by @libraz/formulon. Pick a function to rewrite F2 and recalculate it in the WASM engine. Array functions spill their result down column F.

formulon-cell documentation Open full demo How spilling works

Spreadsheet UI: formulon-cell

Agent interface

Let AI agents work inside real workbooks.

formulon-mcp exposes the Formulon calculation core as MCP tools. Agents can open .xlsx or .xlsb files, inspect structure, edit cells and sheets, recalculate, and save the result.

Set up MCP GitHub

Codex config@libraz/formulon-mcp

[mcp_servers.formulon]
command = "npx"
args = ["-y", "@libraz/formulon-mcp"]

Formulaeval, lookup, trace

Workbookopen, inspect, recalc, save

Editcells, sheets, names, ranges

Layoutmerges, comments, validation

Ecosystem

How the packages relate

L1 is the C++17 calculation core (formulon). L2 provides the WASM, Python, Native Node, and CLI interfaces. L3 contains packages for applications and agents. L4 is the consumer.

L4Consumer

AI agentsClaude Code · Codex · Claude Desktop

Browser appsReact / Vue / vanilla frontends

L3App-facing package

@libraz/formulon-mcpstdio MCP server · 47 tools @libraz/formulon-cellframework-free spreadsheet UI host

@libraz/formulon-cell-react
@libraz/formulon-cell-vue

L2Language interface

@libraz/formulon

npm · WASM binding for browser and Node

formulon

PyPI · Python scripts and batch jobs

formulon (CLI)

GitHub Releases binary · CI and shell

@libraz/formulon-nativeNot on npm

Source build · Node.js N-API addon

L1Calculation core

formulonC++17 calculation core · Excel-derived oracle data (github.com/libraz/formulon)

Dashed packages are not published to npm; build them from a Formulon source checkout.