Headless Spreadsheet Engine

Formulon

Name: Formulon
Author: libraz

A recalculation engine for browser, Python, and CI.

Formulon ships one C++17 calculation core across WASM, Python, and CLI so applications can read, evaluate, recalculate, and write .xlsx / .xlsb files without Excel, Microsoft runtimes, or COM automation.

Quick Start Use from MCP Browse scenarios Try the demo UI

522 / 522: Catalogued functions
92: Oracle categories
31: MCP tools

Agent interface

Let AI agents work inside real workbooks.

formulon-mcp exposes the Formulon calculation core as MCP tools. Agents can open .xlsx 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 is per-language interface packages — @libraz/formulon on npm, formulon on PyPI, plus the CLI binary. L3 is app-facing packages. L4 is the consumer.

L4Consumer

AI agentsClaude Code · Codex · Claude Desktop

Browser appsReact / Vue / vanilla frontends

L3App-facing package

@libraz/formulon-mcpstdio MCP server · 31 tools @libraz/formulon-cellframework-free spreadsheet UI host

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

L2Language interface

@libraz/formulonnpm · WASM binding for browser and Node formulonPyPI · Python scripts and batch jobs formulon (CLI)GitHub Releases binary · CI and shell

L1Calculation core

formulonC++17 calculation core · 522 functions · Excel-derived oracle (github.com/libraz/formulon)

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 handles file upload, formula edits, and preview recalculation — client-side, with no Office runtime.BackendBatch recalculation from PythonMove spreadsheet logic into report generation, ETL pipelines, and scheduled recalc jobs.PipelineWorkbook regression in CIDetect calculation drift continuously with golden workbooks and Excel-derived oracle profiles.AgentEdit workbooks from an AI agentUse MCP tools to open .xlsx files, mutate cells, sheets, names, and layout, then recalculate.

MCPWorkbook operation tools for AI agents RuntimeWASM, Python, and CLI share one C++17 core Use casesBrowser upload, Python batch, and CI workbook regression CompatibilityFull function registration and Excel oracle data

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.

Why this UI exists Open full demo