Exhaustive capability matrix — every feature either library supports, compared side-by-side.

Legend	Meaning
✅	Fully supported
⭐	Supported + superior implementation
🔒	SheetJS Pro only (paid license)
❌	Not supported
🚧	Partial / limited support

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modern-xlsx	SheetJS
Categories won	31	5
Ties	2
Total features	310+	175

modern-xlsx wins: Workbook ops, worksheet ops, cell ops, formulas, merge cells, styling (free), frozen panes, data validation, conditional formatting, hyperlinks, comments, named ranges, page setup, sheet protection, document properties, date utilities, number formatting, rich text, images, barcodes, charts, table layout, tables, print layout, validation/repair, web workers, performance, API design, pivot tables (read-only), threaded comments, slicers, timelines, CLI tool, feature-gated WASM

SheetJS wins: Read formats (18 vs 1), write formats (20 vs 1), I/O ops, sheet conversion, streaming

Ties: Cell reference utilities, shared strings

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Format	modern-xlsx	SheetJS	Notes
XLSX (Office Open XML)	✅	✅	Both full support
XLSM (Macro-enabled)	❌	✅	Data only, no macros
XLSB (Binary)	❌	✅
XLS (BIFF8/5/4/3/2)	❌	✅	Legacy Excel 97-2003
XLML (SpreadsheetML 2003)	❌	✅
ODS (OpenDocument)	❌	✅
FODS (Flat ODS)	❌	✅
CSV	❌	✅
TSV / TXT	❌	✅
HTML tables	❌	✅
SYLK	❌	✅
DIF	❌	✅
PRN	❌	✅
ETH (EtherCalc)	❌	✅
DBF (dBASE)	❌	✅
WK1/WK3/WKS (Lotus)	❌	✅
QPW (Quattro Pro)	❌	✅
Numbers (Apple)	❌	✅	Requires numbers option

Format	modern-xlsx	SheetJS	Notes
XLSX	⭐	✅	modern-xlsx: 8x smaller output
XLSM	❌	✅
XLSB	❌	✅
XLS (BIFF8/5)	❌	✅
XLS (BIFF4/3/2)	❌	✅
XLML	❌	✅
ODS / FODS	❌	✅
CSV	❌	✅	modern-xlsx: string only via sheetToCsv
HTML	❌	✅	modern-xlsx: string only via sheetToHtml
Others (SYLK, DIF, RTF, etc.)	❌	✅	10+ additional legacy formats

Feature	modern-xlsx	SheetJS	Notes
Read from buffer	✅	✅
Read from file	✅	✅
Read sync	❌	✅	modern-xlsx: async-only (WASM)
Write to buffer	✅	✅
Write to file	✅	✅
Write sync	❌	✅
Write to Blob (browser)	⭐	✅	Native WASM Blob
Parse CFB / ZIP	❌	✅
Custom FS / codepage	❌	✅
WASM init	⭐	❌
Encrypted XLSX read/write	⭐	❌	Agile + Standard encryption

Feature	modern-xlsx	SheetJS
Create / get / add / remove sheets	✅	✅ (no remove)
Sheet visibility	❌	✅
Date system	✅	✅
Workbook views	⭐	🚧
Document properties (15 fields)	⭐	🚧
Serialize to JSON	✅	❌
Validate workbook	⭐	❌
Repair workbook	⭐	❌

Feature	modern-xlsx	SheetJS	Notes
Strings, numbers, booleans	✅	✅
Error values	✅	✅
Date values (native type)	✅	✅	cell.dateValue getter
Stub/empty cells	✅	✅	Type "stub" / "z"
Inline strings	✅	❌
Formula strings (type)	✅	❌
Style index	⭐	🔒	modern-xlsx free
Number format getter	✅	✅	cell.numberFormat

Feature	modern-xlsx	SheetJS	Notes
Style builder (fluent API)	⭐	❌
Font (name, size, bold, italic, color, underline, strike)	⭐	🔒	Free vs paid
Fill (solid, 18 patterns, gradient)	⭐	🔒
Border (4 sides + diagonal, 13 styles, colors)	⭐	🔒
Alignment (H/V, wrap, rotation, indent, shrink)	⭐	🔒
Cell protection (locked/hidden)	⭐	🔒
Number format (custom/built-in)	⭐	✅	Community has per-cell .z
DXF / Cell styles / CellXf / Theme colors	⭐	❌

Feature	modern-xlsx	SheetJS
All validation types (list, whole, decimal, date, time, textLength, custom)	⭐	🔒
Input prompts and error alerts	⭐	🔒
Color scales / data bars / icon sets	⭐	🔒
DXF style references / CFVO	⭐	🔒

Feature	modern-xlsx	SheetJS
Add/remove hyperlinks with tooltip	✅	✅ (no tooltip, no remove)
Add/remove comments	✅	✅ (no remove)
Full CRUD named ranges	✅	🚧 (read-only)

Feature	modern-xlsx	SheetJS	Notes
Orientation, paper size, fit-to, scale	✅	❌
Page margins	✅	✅
Sheet protection (14 granular fields)	⭐	🚧
Frozen panes	✅	✅
Auto filter + filter columns	⭐	✅
Headers & footers (odd/even/first)	⭐	❌	HeaderFooterBuilder API
Print titles (repeating rows/cols)	✅	🔒
Print areas	✅	🔒
Row/column grouping (outline 0-7)	⭐	🔒	Collapse/expand API

Feature	modern-xlsx	SheetJS
Column ↔ letter, cell encode/decode, range encode/decode	✅	✅
Encode/decode row, split cell ref	✅	✅
Date ↔ serial, Temporal-like input	⭐	❌
Parse date code	❌	✅

Feature	modern-xlsx	SheetJS
Format cell value	✅	✅
Rich format result (text + color)	⭐	❌
Load custom format / bulk table	✅	✅
Conditional sections	✅	✅
Color codes ([Red], [Color3])	✅	✅
Locale codes ([$-409])	🚧	✅

Feature	modern-xlsx	SheetJS
AoA/JSON → sheet, sheet → JSON/CSV/HTML	✅	✅
Add AoA/JSON to existing sheet	✅	✅
Sheet → TXT	✅	✅
Sheet → formulae	✅	✅
Sheet → row objects (alias)	❌	✅
DOM table → sheet/book	❌	✅

Feature	modern-xlsx	SheetJS
Stream to JSON/CSV/HTML/XLML	❌	✅
WASM streaming reader (SAX)	⭐	❌
Parallel sheet parsing (rayon)	⭐	❌

Feature	modern-xlsx	SheetJS
RichTextBuilder (bold, italic, colored, styled)	⭐	❌
Image embedding (PNG/JPEG/GIF)	⭐	🔒
Charts (create)	⭐ 10 types, ChartBuilder API, trendlines, error bars, 3D, combo	🔒

Feature	modern-xlsx	SheetJS	Notes
9 barcode types + PNG renderer + XLSX embed	⭐	❌
Table layout engine (drawTable/drawTableFromData)	⭐	❌
Native Excel Tables (ListObjects)	⭐	🔒	Full CRUD + 60 built-in styles
Workbook validation & repair	⭐	❌
Web Worker support	⭐	❌

Feature	modern-xlsx	SheetJS	Notes
Used range (ws.usedRange)	✅	✅
Tab color (ws.tabColor)	✅	🚧
Dynamic array formulas (SPILL)	✅	✅	cm="1" attribute

Benchmark	modern-xlsx	SheetJS	Ratio
Read 100K rows	faster	baseline	~4.0x
Write 100K batch	faster	baseline	~8.4x
Write 10K cell-by-cell	baseline	faster	~0.7x
Output file size	smaller	baseline	~8x
aoaToSheet 50K rows	faster	baseline	~1.6x
sheetToJson 10K rows	baseline	faster	~0.6x
sheetToCsv 10K rows	tied	tied	~1.0x
Bundle size	~300KB (WASM)	~200KB (JS)	1.5x larger
Zero runtime deps	✅	❌
TypeScript types	120+ types	basic
Multi-threading	rayon flag	❌

Feature	modern-xlsx	SheetJS	Notes
Pivot tables (read-only)	⭐	🔒	Full OOXML parsing
Threaded comments (read + write)	⭐	❌	Modern Excel threads
Slicers (read-only)	⭐	❌	Pivot table filtering
Timelines (read-only)	⭐	❌	Date-based filtering
CLI tool (info/convert)	⭐	❌	npx modern-xlsx
Feature-gated WASM	⭐	❌	Cargo features
Structured error handling	⭐	❌	ModernXlsxError with .code

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See the full comparison with 310+ features in __tests__/feature-comparison.test.ts