excel_plus — fast, low-memory Excel (.xlsx) library for Dart and Flutter

Excel (.xlsx) Library for Dart & Flutter #

excel_plus is a fast, low-memory, non-UI Dart library for creating, reading, editing, and styling Microsoft Excel .xlsx spreadsheets. It works in plain Dart and in Flutter apps, on the VM, Web (JS & WASM), and mobile. excel_plus is a source-compatible drop-in replacement for the excel package — change one import and your existing code keeps working, with far more features, better performance on large workbooks, and active maintenance.

⭐ Find this useful? Star it on GitHub and 👍 like it on pub.dev — it helps other Dart & Flutter developers discover a maintained, full-featured Excel library.

Overview #

excel_plus reads and writes the Office Open XML .xlsx format used by Microsoft Excel, Google Sheets, and LibreOffice Calc. It parses workbooks with a streaming (SAX) reader and loads each sheet lazily, so memory stays low even on large files, and it reuses untouched parts of a workbook byte-for-byte when saving.

What you can do with it:

Read and parse existing .xlsx files, or create new Excel workbooks from scratch.
Edit cells, rows, columns, and multiple sheets, then save back to .xlsx.
Style spreadsheets — fonts, colors, fills, borders, alignment, number formats, and merged cells.

A styled Excel sheet produced by excel_plus: a merged green title, a bold header row, colored Paid/Due status cells, borders, and currency formatting

Performance #

excel_plus is built for large workbooks: a streaming SAX parser instead of full-DOM parsing, lazy per-sheet loading, O(1) reverse indexes for styles and shared strings, and byte-for-byte reuse of untouched workbook parts on save.

It comfortably handles workbooks with millions of cells. Here is a head-to-head against the original excel package — same machine, same workload:

excel_plus vs excel — encode, decode and peak memory at 1M and 5M cells

Workload	Encode (`excel` → excel_plus)	Decode	Peak memory	Create
5,000,000 cells	48.8 s → 9.2 s · 5.3×	56.8 s → 19.5 s · 2.9×	12.0 GB → 2.6 GB · 4.6×	≈ equal
1,000,000 cells	9.4 s → 1.6 s · 5.8×	10.9 s → 3.7 s · 3.0×	2.5 GB → 0.7 GB · 3.5×	≈ equal
10,000 cells	184 ms → 41 ms · 4.5×	141 ms → 75 ms · 1.9×	≈ equal*	≈ equal
500 cells	54 ms → 16 ms · 3.3×	32 ms → 19 ms · 1.7×	≈ equal*	≈ equal

_{* Below ~100k cells peak memory is dominated by the Dart VM baseline (~250 MB), so
it is comparable; the gap widens with size (3.5× at 1M → 4.6× at 5M, where excel
needed ~12 GB RAM). Create time is within noise — both build cells the same way.}

The two libraries pin conflicting archive/xml majors, so they can't run in one program; each harness lives in its own package under benchmark/compare/. Timings vary by hardware — reproduce both on your own machine:

cd benchmark/compare/excel_baseline   && dart pub get && dart run bin/benchmark.dart
cd ../excel_plus_bench                && dart pub get && dart run bin/benchmark.dart

Table of contents #

Excel (.xlsx) Library for Dart & Flutter

Key features #

A complete read / create / edit toolkit for .xlsx, on every Dart & Flutter platform. Expand a group for details:

📄 Core & platform

Read, create & edit .xlsx
Multiple sheets — create, copy, rename, delete
All cell types — text, int, double, bool, date, time, datetime, formula
Cross-platform — VM, web (dart2js + wasm) & Flutter mobile
Source-compatible drop-in for the excel package

🎨 Cells, styling & text

Cell styling — font, fill, borders, alignment, rotation, wrap
Number formats — standard & custom
Rich text (read & write)
Theme & indexed colours
Merge & unmerge

📐 Rows, columns & layout

Insert / delete / clear rows & columns
Column width, row height & auto-fit
Grouping & outline levels
Page & print setup

🧩 Worksheet features

Hyperlinks
Data validation / dropdowns
Conditional formatting
Freeze & split panes
Autofilter
Sheet & workbook protection
Defined names / named ranges

📊 Formulas & data tools

Formula-evaluation engine — ~130 functions (function reference), plus registerFunction for your own
Excel tables (ListObjects)
Pivot tables — read & write (row / column / page / nested fields + measures)
Find & replace

🖼️ Objects & media

Charts — read & write (column, bar, line, area, pie, doughnut, scatter)
Images
Comments / notes

🛡️ Reliability & performance

Typed exceptions — ExcelException + subtypes
Lazy per-sheet parsing & SAX streaming for large files
Round-trip safety — unmodeled parts preserved byte-for-byte

Limitations #

❌ Long-tail statistical, engineering & database functions (register your own)
❌ Dynamic-array spilling across the grid
❌ R1C1-style references (A1-style only)

Roadmap #

Planned next — direction is driven by what users request on the issue tracker:

⬜ More formula functions — long-tail statistical, engineering & database (D-)
⬜ Dynamic-array spilling across the grid
⬜ Streaming / sink encode to cap peak memory on very large saves

Shipped milestones are in the changelog.

Error handling #

Opening or saving a file throws a typed, catchable ExcelException. Catch the base type for any failure, or narrow to a specific kind — each carries a message, an optional part (the package part involved), and an optional cause:

try {
  final excel = Excel.decodeBytes(bytes);
  // ... edit ...
  excel.save();
} on ExcelArchiveException catch (e) {
  // Not a readable .xlsx (bad ZIP, or a required part is missing).
  print('Not a usable file: ${e.message}');
} on ExcelFormatException catch (e) {
  // A valid ZIP, but its XML is malformed/inconsistent.
  print('Corrupt content in ${e.part}: ${e.message}');
} on ExcelException catch (e) {
  // Any other excel_plus failure (e.g. ExcelEncodeException on save).
  print('Workbook error: ${e.message}');
}

Invalid arguments you pass to the API (a negative cell index, an empty table name, an out-of-range row) throw ArgumentError, the standard Dart type for programming errors — they are not ExcelExceptions. A malformed formula is not thrown either: it evaluates to an #ERROR! cell value.

Example #

▶ Try the live demo — build, style and export real .xlsx files right in your browser. No install needed.

A complete, runnable sample lives in the example/ directory. Clone the repository and run it, or copy any snippet from Getting started below.

Installation #

dart pub add excel_plus
# or, in a Flutter app:
flutter pub add excel_plus

Then import it:

import 'package:excel_plus/excel_plus.dart';

Getting started #

Create a simple Excel document #

final excel = Excel.createExcel(); // a new workbook with one default sheet
final sheet = excel['Sheet1'];

sheet.updateCell(CellIndex.indexByString('A1'), TextCellValue('Hello, world!'));

final bytes = excel.save(); // List<int> of the .xlsx file

Add text, number, boolean, and date values #

sheet.updateCell(CellIndex.indexByString('A1'), TextCellValue('Name'));
sheet.updateCell(CellIndex.indexByString('B1'), IntCellValue(42));
sheet.updateCell(CellIndex.indexByString('C1'), DoubleCellValue(3.14));
sheet.updateCell(CellIndex.indexByString('D1'), BoolCellValue(true));
sheet.updateCell(CellIndex.indexByString('E1'), DateCellValue(year: 2026, month: 6, day: 9));
sheet.updateCell(CellIndex.indexByString('F1'), TimeCellValue(hour: 9, minute: 30, second: 0));
sheet.updateCell(
  CellIndex.indexByString('G1'),
  DateTimeCellValue(year: 2026, month: 6, day: 9, hour: 9, minute: 30),
);

Add formulas #

Formulas are stored and round-tripped as text, and excel_plus can also evaluate them: sheet.evaluate(cell) returns the computed value, and excel.recalculate() writes each formula's result into its cached value (so a saved file shows results). See the formula functions reference for the ~130 built-in functions.

sheet.updateCell(CellIndex.indexByString('A1'), IntCellValue(10));
sheet.updateCell(CellIndex.indexByString('A2'), IntCellValue(20));
sheet.updateCell(CellIndex.indexByString('A3'), FormulaCellValue('SUM(A1:A2)'));

// ...or set a formula on an existing cell:
sheet.cell(CellIndex.indexByString('A4')).setFormula('AVERAGE(A1:A2)');

// Evaluate one cell, or recompute the whole workbook:
print(sheet.evaluate(CellIndex.indexByString('A3'))); // 30
excel.recalculate(); // store every formula's computed result

// Register a custom function, callable as =TRIPLE(A1):
excel.formula.registerFunction('TRIPLE', (args) {
  final v = args.isEmpty ? null : args.first;
  return IntCellValue((v is IntCellValue ? v.value : 0) * 3);
});

Read an existing Excel file #

import 'dart:io';

final bytes = File('input.xlsx').readAsBytesSync();
final excel = Excel.decodeBytes(bytes);

for (final sheetName in excel.tables.keys) {
  for (final row in excel[sheetName].rows) {
    print(row.map((cell) => cell?.value).toList());
  }
}

Read a single cell #

final cell = excel['Sheet1'].cell(CellIndex.indexByString('B2'));
print(cell.value); // a typed CellValue: TextCellValue, IntCellValue, ...

Style a cell — font, color, fill, alignment #

sheet.updateCell(
  CellIndex.indexByString('A1'),
  TextCellValue('Header'),
  cellStyle: CellStyle(
    bold: true,
    italic: true,
    fontSize: 14,
    fontColorHex: ExcelColor.white,
    backgroundColorHex: ExcelColor.fromHexString('#21A366'),
    horizontalAlign: HorizontalAlign.Center,
    verticalAlign: VerticalAlign.Center,
  ),
);

Add borders #

sheet.cell(CellIndex.indexByString('A1')).cellStyle = CellStyle(
  leftBorder: Border(borderStyle: BorderStyle.Thin),
  rightBorder: Border(borderStyle: BorderStyle.Thin),
  topBorder: Border(borderStyle: BorderStyle.Medium),
  bottomBorder: Border(borderStyle: BorderStyle.Medium, borderColorHex: ExcelColor.red),
);

Apply number formats #

// Currency with a thousands separator (custom format code).
sheet.updateCell(
  CellIndex.indexByString('A1'),
  DoubleCellValue(12500.5),
  cellStyle: CellStyle(numberFormat: NumFormat.custom(formatCode: r'$#,##0.00')),
);

// Percentage (built-in format).
sheet.updateCell(
  CellIndex.indexByString('A2'),
  DoubleCellValue(0.125),
  cellStyle: CellStyle(numberFormat: NumFormat.standard_10), // 0.00%
);

Merge and unmerge cells #

sheet.merge(
  CellIndex.indexByString('A1'),
  CellIndex.indexByString('D1'),
  customValue: TextCellValue('Merged title'),
);

sheet.unMerge('A1:D1');

Insert and delete rows and columns #

sheet.insertRow(2);    // insert a blank row at index 2
sheet.removeRow(5);    // delete row 5
sheet.insertColumn(1); // insert a blank column at index 1
sheet.removeColumn(3); // delete column 3

Append a row #

sheet.appendRow([
  TextCellValue('Alice'),
  IntCellValue(30),
  DoubleCellValue(12500.0),
]);

Column width, row height, and auto-fit #

sheet.setColumnWidth(0, 24.0);
sheet.setRowHeight(0, 32.0);
sheet.setColumnAutoFit(1);

Work with multiple sheets #

final excel = Excel.createExcel();
excel['Sales'].updateCell(CellIndex.indexByString('A1'), TextCellValue('Q1'));
excel['Inventory'].updateCell(CellIndex.indexByString('A1'), TextCellValue('SKU'));

excel.rename('Sales', 'Revenue');
excel.copy('Revenue', 'Revenue (Backup)');
excel.delete('Inventory');
excel.setDefaultSheet('Revenue');

Find and replace #

// Within one sheet — returns the number of replacements made.
final count = excel['Sheet1'].findAndReplace('draft', 'final');

// Across a named sheet via the workbook.
excel.findAndReplace('Sheet1', 'old', 'new');

Save the workbook #

// 1) As bytes.
final List<int>? bytes = excel.save();

// 2) To a file (Dart VM / desktop / mobile).
import 'dart:io';
File('output.xlsx').writeAsBytesSync(excel.save()!);

// 3) Trigger a browser download on Flutter Web.
excel.save(fileName: 'report.xlsx');

Flutter — read from assets, edit, and save #

import 'package:flutter/services.dart';
import 'package:path_provider/path_provider.dart';

final data = await rootBundle.load('assets/template.xlsx');
final excel = Excel.decodeBytes(data.buffer.asUint8List());

excel['Sheet1'].updateCell(CellIndex.indexByString('A1'), TextCellValue('Updated'));

final dir = await getApplicationDocumentsDirectory();
File('${dir.path}/output.xlsx').writeAsBytesSync(excel.save()!);

Charts #

Add a chart over a data range; charts in an opened file are read back via sheet.charts.

// Assuming category labels in A2:A4 and values in B2:B4...
sheet.addChart(Chart.column(
  anchor: CellIndex.indexByString('D2'),
  title: 'Quarterly sales',
  categories: 'A2:A4',
  series: [ChartSeries(name: 'Sales', values: 'B2:B4')],
));

for (final c in sheet.charts) {
  print('${c.type} • ${c.series.length} series');
}

Also Chart.bar, Chart.line, Chart.area, Chart.pie, Chart.doughnut, and Chart.scatter.

Colour series — and individual pie/doughnut slices — explicitly; anything left unset uses a built-in Office palette:

// per-series colour (column/bar/line/area/scatter)
sheet.addChart(Chart.column(
  anchor: CellIndex.indexByString('D2'),
  categories: 'A2:A4',
  series: [
    ChartSeries(name: 'Sales', values: 'B2:B4',
        color: ExcelColor.fromHexString('FF2962FF')),
  ],
));

// per-slice colours for pie/doughnut (index-aligned to the values;
// a short list colours the leading slices and palettes the rest)
sheet.addChart(Chart.pie(
  anchor: CellIndex.indexByString('D20'),
  categories: 'A2:A4',
  series: ChartSeries(values: 'B2:B4', pointColors: [
    ExcelColor.fromHexString('FF4285F4'),
    ExcelColor.fromHexString('FF34A853'),
    ExcelColor.fromHexString('FFFBBC04'),
  ]),
));

Pivot tables #

sheet.addPivotTable(PivotTable(
  name: 'ByRegion',
  anchor: CellIndex.indexByString('F1'),
  sourceFrom: CellIndex.indexByString('A1'), // header row
  sourceTo: CellIndex.indexByString('C13'),
  rowField: 0,                               // group by the 1st column
  dataFields: [PivotDataField(2, function: PivotFunction.sum)],
));

// Pivots in an opened file are read back into sheet.pivotTables.

Conditional formatting #

final from = CellIndex.indexByString('B2');
final to = CellIndex.indexByString('B20');

// Bold-red any value greater than 100.
sheet.addConditionalFormat(
  from,
  to,
  ConditionalFormat.greaterThan(
    100,
    style: CellStyle(bold: true, fontColorHex: ExcelColor.red),
  ),
);

// ...or a 3-colour heat map across the range.
sheet.addConditionalFormat(
  from,
  to,
  ConditionalFormat.colorScale(
    min: ExcelColor.red,
    mid: ExcelColor.yellow,
    max: ExcelColor.green,
  ),
);

// A dropdown of fixed choices on B2.
sheet.setDataValidation(
  CellIndex.indexByString('B2'),
  DataValidation.list(['Low', 'Medium', 'High'], prompt: 'Pick a priority'),
);

// A whole-number range applied to B3:B10.
sheet.setDataValidation(
  CellIndex.indexByString('B3'),
  DataValidation.wholeNumber(min: 1, max: 100),
  end: CellIndex.indexByString('B10'),
);

Hyperlinks #

sheet.setHyperlink(
  CellIndex.indexByString('A1'),
  Hyperlink.url('https://pub.dev', tooltip: 'Open pub.dev'),
);
sheet.setHyperlink(
  CellIndex.indexByString('A2'),
  Hyperlink.location("'Sheet2'!A1"), // jump within the workbook
);
sheet.setHyperlink(
  CellIndex.indexByString('A3'),
  Hyperlink.email('dev@example.com', subject: 'Hello'),
);

Freeze panes #

// Keep the top row and first column in view while scrolling.
sheet.freezePanes(rows: 1, columns: 1);

// ...or independent split panes instead (offsets in twips, 1/20 pt).
sheet.splitPanes(xSplit: 2400, ySplit: 1200, topLeftCell: 'C3');

Excel tables #

sheet.addTable(ExcelTable(
  name: 'Sales',
  from: CellIndex.indexByString('A1'),
  to: CellIndex.indexByString('C13'),
  style: TableStyle.medium9,
));

Insert an image #

import 'dart:io'; // Dart VM / desktop / mobile

final bytes = File('logo.png').readAsBytesSync(); // PNG / JPEG / GIF
sheet.insertImage(
  bytes,
  anchor: CellIndex.indexByString('E2'),
  width: 120,
  height: 60,
);

// Images in an opened file are available via sheet.images.

Cell comments #

sheet.setComment(
  CellIndex.indexByString('A1'),
  Comment('Reviewed and approved', author: 'QA'),
);

excel_plus vs excel #

excel_plus is a performance-focused fork of the excel package that keeps the same public API.

	excel_plus	excel
XML parsing	Streaming SAX (`parseEvents`)	Full-DOM (standard)
Sheet loading	Lazy, per sheet on first access	Eager
Large-file memory	Low — untouched parts reused byte-for-byte on save	Higher
Public API	Source-compatible drop-in	— (the original)
Platforms	VM, Web (JS & WASM), Android, iOS, desktop	VM, Web, mobile

On a 1,000,000-cell sheet this measured ~5× faster encoding, ~3× faster decoding, and ~3.5× less peak memory — see Performance for the reproducible head-to-head.

Live pub score and likes are shown in the badges at the top.

Migrating from the excel package #

// Before
import 'package:excel/excel.dart';

// After
import 'package:excel_plus/excel_plus.dart';

No other code changes needed for typical usage — excel_plus mirrors the excel package's public API.

FAQ #

Is excel_plus a drop-in replacement for the excel package? Yes. The classes, methods, and enums match the excel package — change the import to package:excel_plus/excel_plus.dart and your existing code keeps working.

Which platforms are supported? Dart VM, Web (both JavaScript and WebAssembly), and mobile (Android & iOS) via Flutter, as well as desktop. It is a pure-Dart package with no dart:io in the public path.

Can it read and write large .xlsx files efficiently? Yes — sheets are parsed with a streaming SAX reader and loaded lazily, and untouched parts of the workbook are reused byte-for-byte on save, keeping memory low.

Does it support formulas, styling, and merged cells? Yes — formula cells, full cell styling (fonts, colors, fills, borders, alignment, number formats), and merging/unmerging with custom values are all supported.

Is it Flutter-only? No. excel_plus is a pure Dart library; it works in plain Dart and in Flutter apps alike.

Support and feedback #

Found a bug or want a feature? Open an issue on the issue tracker.
Questions and ideas are welcome via GitHub Discussions.
Pull requests are welcome — see the repository for contribution guidelines.

About #

excel_plus is an open-source, MIT-licensed, performance-focused fork of the excel package, rebuilt around a streaming parser and lazy loading for speed and low memory on large .xlsx files while staying API-compatible.

excel_plus is created and owned by Nurullah Al Masum.

Contributors #

excel_plus grows with its community — every contributor is listed here:

Want to help? Pull requests are welcome — see Support and feedback.

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