Spreadsheet generation API

Generate real Excel workbooks from structured data.

CmdCal XLSX turns application data, template-driven reporting, and agent output into native `.xlsx` files without imperative workbook spaghetti.

[01] Why it exists

Replace exporter code that keeps getting more fragile.

The point is not to produce cells somehow. The point is to ship workbooks that are usable, styled, inspectable, and safe to automate.

Declarative generation

Describe the workbook, not every workbook mutation

Define sheets, rows, tables, validations, formulas, and print behavior as data. Keep the business logic in your application instead of scattering it through imperative workbook calls.

Structured JSON in
Deterministic OOXML out
Typed workbook validation before render

1contract across app, API, and agents

Operational trust

Validate and repair instead of hoping Excel opens it cleanly

CmdCal includes workbook-quality inspection, conservative repair, and explicit findings so teams can review risky artifacts before they reach users.

Workbook validation
Conservative repair logs
Preflight signals for large workloads

0silent workbook mutations

Production workflows

Templates, large workbooks, and MCP-compatible automation

Move past toy exports with template inspection, table-aware assembly, formula support, and agent tooling that can generate, validate, and repair workbook artifacts.

Template-backed assembly
Native tables and filters
MCP spreadsheet tooling

3high-value workflow layers in one engine

[02] Comparison

CmdCal XLSX vs imperative workbook libraries.

The important distinction is not language preference. It is whether the spreadsheet system behaves like infrastructure or like a bag of workbook mutations.

Capability	CmdCal XLSX	ExcelJS	SheetJS
Primary model	Declarative workbook AST	Imperative workbook mutation	Low-level workbook utilities
Template workflow	Template inspection and clean assembly	Manual workbook mutation	Manual workbook mutation
Quality layer	Preflight, validate, repair	None built in	None built in
Agent fit	JSON contract + MCP tools	Custom wrappers required	Custom wrappers required
Large-workbook planning	Render planning and metrics	DIY instrumentation	DIY instrumentation

[03] Start here

The shortest path to first XLSX value.

These are the pages that matter if you want to move from curiosity to a real workbook pipeline quickly.

First render

XLSX Quickstart

Render a real workbook from structured JSON and understand the minimum viable contract.

Operational trust

Validation & Repair

Inspect workbook findings, run repairs, and keep risky output explicit instead of silent.

High-value workflows

Templates & Large Workbooks

Work honestly with template-backed assembly and workbook sizes that need planning, not guesswork.

Agent workflows

MCP & Agents

Generate, validate, and repair spreadsheets from agent workflows without inventing your own tool boundary.

[04] Fit

Where CmdCal XLSX is the right tool.

This is strongest when the workbook is part of a product, a recurring report flow, or an agent pipeline, not a one-off office macro.

Capability	Use case	Fit
Customer-facing exports from app data	Customer-facing exports from app data	Strong fit
Template-backed operational reports	Template-backed operational reports	Strong fit
Agent-generated spreadsheets with validation	Agent-generated spreadsheets with validation	Strong fit
Hand-authored desktop spreadsheet workflows	Hand-authored desktop spreadsheet workflows	Lower fit
Teams expecting silent best-effort repair	Teams expecting silent best-effort repair	Poor fit

Ship your first workbook flow.

Start with the quickstart, then move into validation, templates, and agent workflows once the core export shape is proven.

Read XLSX docs