Notepad Web

A faithful, fully-offline web / Chrome-extension port of Notepad++ (via NotepadNext), powered by CodeMirror 6 and Wasmoon (Lua 5.4 in WASM).

⬇  Install from the Chrome Web Store

Notepad Web is an independent project and is not affiliated with, endorsed by, or sponsored by Notepad++ or NotepadNext.

Why this exists

Notepad Web started as a labor of love: an attempt to bring the Notepad++ experience that so many of us grew up with into the browser, for the times the desktop app isn't within reach. Notepad++ is deep and battle-tested, and — being honest — not every feature crosses over to a browser sandbox smoothly. Some had to be reworked, and some are still on the way (see Known limitations for the honest gaps).

It's also built and tested by one person, so coverage only stretches as far as one pair of hands and one machine allow. If something feels off while you're using it, please open an issue — I genuinely appreciate it. Every report is read and triaged in good faith, and the ones that point to real problems are prioritised. Bit by bit, that feedback is what makes Notepad Web more stable and a nicer place to write.

Thank you for giving it a try. 💚

What it is

Notepad Web is a GPL-3.0 web port of NotepadNext (which itself reimplements Notepad++). It bundles NotepadNext's real .lua language definitions and toolbar icons, then executes them inside Chrome via Wasmoon (Lua 5.4 compiled to WASM), reproducing the authentic Notepad++ light theme and language-detection logic without any remote requests.

The extension works 100% offline. It requires no server, makes no network calls, and requests only the storage permission.

Features

Editor core

• CodeMirror 6 editor core: fast, accessible, MV3-compatible.
• Wasmoon Lua-in-WASM: executes the real NotepadNext init.lua + per-language .lua palette files for faithful Notepad++ syntax colours.
• Language detection from file extension via the real .lua language registry — same logic as the desktop app.
• Faithful Notepad++ light theme (token colours, status bar, chrome).
• tabSize and wordWrap settings with per-tab state and cross-tab inheritance for new tabs.
• Open/save real files (File System Access API) with upload/download fallback.
• Session restore for unsaved buffers and cursor/scroll position (IndexedDB).
• Menu bar (File / Edit / View / Search / Language / Tools) with keyboard accelerators.
• Dockview multi-pane dock panel layout.

Editor decorators

• Bookmarks: gutter markers, toggle (Ctrl+F2), next/prev (F2/Shift+F2), clear all, invert, cut/copy/delete bookmarked lines.
• Mark All Occurrences: 3 distinct highlight styles + Clear per-style / Clear All.
• Clickable URL links: Ctrl/Cmd+click to open in a new tab.
• HTML tag auto-close: typing > closes the open tag.
• Bracket matching, selection-match highlighting, word autocompletion, auto-close/surround brackets.

Macros + Lua Console

• Macro record/replay: Start/Stop Recording, Playback (Ctrl+Shift+P), run N times or to end-of-file, save/run named macros.
• Lua Console dock: persistent Wasmoon REPL with an editor API bridge over the active document.

Search system

• 3-tab Find / Replace / Mark dialog (Ctrl+F / Ctrl+H): match-case, whole-word, wrap-around, backwards, Normal/Extended/Regex modes; MRU history.
• Find in all open documents → clickable Search Results dock.
• Mark All + Copy Marked Text; Search-and-Bookmark (bookmark all matching lines).

Extension compliance

• 100% offline, zero telemetry, zero remote requests.
• MV3 CSP: script-src 'self' 'wasm-unsafe-eval'; object-src 'self'.
• Permissions: ["storage"] only.

Install

From the Chrome Web Store (recommended)

➜ Install Notepad Web — one click, auto-updates.

From source (for development)

git clone https://github.com/codecancu/notepad-web.git
cd notepad-web
npm ci
npm run build      # produces dist/

Then in Chrome:

1. Open chrome://extensions.
2. Enable Developer mode (top-right toggle).
3. Click Load unpacked and select the dist/ folder.

Development

npm run dev        # webpack watch build
npm test           # unit tests (Vitest)
npm run test:e2e   # Playwright end-to-end tests
npm run lint       # ESLint + Prettier check
npm run typecheck  # tsc --noEmit
npm run package    # manifest-compliance + no-remote-code checks, then zips dist/

The npm run package step verifies that no CDN/remote URLs survived the build and that the manifest declares only allowed permissions before producing notepad-web-v0.3.0.zip.

Architecture

• CodeMirror 6 (@codemirror/*, @lezer/*) provides the editor core, language parsers, and decoration system.
• Wasmoon runs the real NotepadNext init.lua and per-language .lua files inside the extension (Lua 5.4 compiled to WASM), reproducing authentic syntax highlighting and theme colours with no native code or remote requests.
• dockview-core manages the multi-panel dock layout (Document Map, Function List, Lua Console, Search Results).
• MV3 compliance: permissions are ["storage"] only; CSP is script-src 'self' 'wasm-unsafe-eval'; a build-time scan (scripts/package.mjs) asserts zero CDN/remote URL literals survive in dist/*.js.

Known limitations

• EditorConfig (.editorconfig) is not supported — walking parent directories is not permitted by the File System Access API for single-file opens.
• Find-in-Files searches only open documents (faithful to NotepadNext; directory- recursive search exceeds browser sandbox constraints).
• Recent Files require re-picking — File System Access API handles are not persistable across browser sessions.

Performance

Files > 25 MB warn; > 100 MB are refused (browser memory limits). For very large files use a native desktop editor such as NotepadNext or Notepad++.

Credits / Acknowledgements

Notepad Web stands on the shoulders of:

• NotepadNext by Justin Dailey — https://github.com/dail8859/NotepadNext (GPL-3.0). Notepad Web is a faithful web port of NotepadNext; it bundles NotepadNext's .lua language definitions and toolbar icon PNGs. NotepadNext is the upstream desktop application this project derives from.

• Notepad++ — the original editor that NotepadNext reimplements, and the spiritual ancestor of this project. Notepad++ is the work of its respective authors and is not affiliated with Notepad Web.

• CodeMirror 6 (MIT) — https://codemirror.net/. The editor core.

• Wasmoon (MIT) — https://github.com/ceifa/wasmoon. Lua 5.4 compiled to WASM, enabling NotepadNext's Lua scripts to run inside the extension.

• dockview (MIT) — https://github.com/mathuo/dockview. Multi-pane dock layout.

• FamFamFam Silk icons (CC-BY 3.0) by Mark James — the toolbar and menu icons used in both NotepadNext and this port.

See THIRD_PARTY_LICENSES.md for the full dependency list.

Disclaimer

Notepad Web is an independent project and is not affiliated with, endorsed by, or sponsored by Notepad++ or NotepadNext. Notepad++ and NotepadNext are the works of their respective authors.

License

GPL-3.0-or-later. See LICENSE.

Notepad Web is a derivative work of NotepadNext (© Justin Dailey, GPL-3.0), which itself is a reimplementation of Notepad++. The GPL-3.0-or-later license applies to all original contributions in this repository.

Contributing

Contributions are welcome. Please read CONTRIBUTING.md for the workflow, DCO sign-off requirement, and code style guide. All contributors must follow the CODE_OF_CONDUCT.md.