Fonts, colours, borders, merged cells, conditional formatting and recalculated formulas, in a 27 KB library that does its parsing in a Web Worker.

50,000-row workbook

Open in Node

First view in the browser

Longest page freeze

Memory

Gzipped size

Plain-text workbook, compared with SheetJS 0.20.3 on one modern computer. Figures are medians of 7 benchmark runs.

import { openWorkbook } from 'eatsheet/worker';
import 'eatsheet/eatsheet.css';

const book = await openWorkbook(file);
container.innerHTML = (await book.render(0)).html;

Good fit: previewing files people upload, in a data room, a document portal or an internal tool.

Use SheetJS instead if you need to write files, or read .xls, .xlsb or .ods.