TeXbrain

A free, open-source LaTeX editor that runs entirely in your browser.
No accounts. No installs. No servers. Just open a tab and write.

Try it now → tex.swimmingbrain.dev

I built this because I was tired of paying for features that should be free. I wrote my thesis last year in LaTeX and spent more time fighting tooling than actually writing. Online solutions lock git sync behind a paywall. Local setups break between machines. I wanted something that just works. Open a browser, write LaTeX, get a PDF.

So I built it.

What it does

texbrain is a full LaTeX editor that compiles your .tex files to PDF directly in the browser. There is no backend. No server processing your files. Everything (the editor, the compiler, the git client) runs client-side.

You can open a local project folder, edit your files, see the PDF update, commit your changes, and push to GitHub. All from one tab.

Features

• LaTeX compilation in the browser. Uses a WebAssembly port of pdfTeX (SwiftLaTeX). Your .tex files are compiled to PDF without ever leaving your machine. Packages are loaded on demand and cached locally, so the first compile only downloads what your document actually uses. Recompilations take 1 to 5 seconds depending on project complexity.
• Most of CTAN, loaded on demand. Common packages ship with the app. Anything else (memoir, abntex2, KOMA-Script, you name it) is resolved automatically from a TeX Live mirror the first time a document needs it, then cached locally for offline use.
• Live PDF preview. Rendered with pdf.js. Multi-page, zoomable, with text selection.
• Full git integration. Clone repos, create branches, stage files, commit, push, pull, merge. All powered by isomorphic-git running in the browser, directly on your project folder, so a terminal and TeXbrain see the same repository. No CLI needed. See Git, step by step.
• Local file system access. Uses the File System Access API to read and write directly to your project folder on disk (Chrome/Edge).
• Multi-file projects. File tree, tabs, drag-and-drop. Supports .tex, .bib, .sty, .cls and more.
• CodeMirror 6 editor. Syntax highlighting, autocomplete for 70+ LaTeX commands, bracket matching, code folding, snippets, dark/light theme.
• Command palette. Quick access to actions via keyboard shortcut.
• Snippet picker. Math environments, document structures, Greek letters, common commands. Searchable and categorized.
• Works offline. Once loaded, the app works without an internet connection. Compilation is local, editing is local. Packages you've compiled with before are cached; only a package you've never used needs the network once.
• Project templates. Start from scratch or pick a template (article, thesis, beamer, report, CV, letter, minimal).

How it works under the hood

There's no magic and no backend.

Editor. Built on CodeMirror 6 with a custom LaTeX grammar (Lezer parser), autocomplete provider, and theme system. The editor supports multiple open files via tabs and writes straight to the files on disk, which is also where git looks.

Compiler. LaTeX compilation uses SwiftLaTeX's pdfTeX engine compiled to WebAssembly. The engine runs in a memory filesystem (MEMFS), where your project files are written before each compilation. When the engine asks for a file it doesn't have (a class, package, font, ...), the service worker resolves it through a chain: previously cached files first, then the package subset bundled with the app, then a TeX Live mirror (a texmf-dist mirror on jsDelivr, with a community SwiftLaTeX server as fallback). Every resolved file is stored in the browser's cache storage, so each package is downloaded at most once. After the first successful compile, the bundled subset is also prefetched in the background so the core package set works offline.

Git. All git operations use isomorphic-git, a pure JavaScript implementation of git. It runs straight on your project folder through a small adapter around the File System Access API, so the .git directory lives next to your .tex files like it would with a terminal, and a folder that already is a repository is picked up as is. Remote operations (push/pull/clone) go through a CORS proxy since browsers can't speak the git protocol directly.

PDF viewer. Rendered with pdf.js, Mozilla's PDF rendering library. Supports multi-page rendering with a text layer for selection and search.

File system. The app uses the File System Access API to read/write your actual files on disk. This requires a Chromium-based browser (Chrome, Edge, Arc, Brave). For other browsers, there's a fallback using the Origin Private File System (OPFS).

Frontend. SvelteKit with the static adapter. The entire app is pre-built to static HTML/CSS/JS and deployed to GitHub Pages. No SSR, no API routes, no server. Tailwind CSS handles styling.

When something doesn't compile

LaTeX errors are famous for being unreadable, so TeXbrain does the reading for you. The Problems tab turns the log into cards: a headline in plain words ("Unknown command \foo", "Math outside math mode", "Package doesnotexist not found"), what it means, what to try, the file and line, and the source line exactly as TeX read it with a bar where it stopped. Click a card and the editor jumps there, opening the file if it has to. Errors that TeX can't place, a missing package for example, are placed by searching your sources for them.

Warnings get the same treatment (undefined labels, citations, hyperref bookmarks). Notes about margins and stretched lines are there too, hidden until you switch them on. Every card can be copied as text, "Copy all" gives you a report to paste anywhere, and problems that look like TeXbrain's fault rather than your document's have a link that opens a prefilled issue.

The Log tab still has everything the engine printed, with colors, line numbers, search, a full/clean toggle, copy and download.

Git, step by step

Git in TeXbrain works on the folder you opened, the same way a terminal would. A hidden .git directory sits next to your .tex files, so you can switch between TeXbrain, the command line and any other editor without anything getting out of sync. Folders that already are repositories are picked up as they are, history included.

1. Start tracking a project. Open a folder, press the Git button (or Ctrl+G), fill in your name and email once and hit Start. TeXbrain offers a .gitignore for the files LaTeX leaves behind while compiling.
2. Commit. Save your files, open the Changes tab, stage what you want in the commit (or stage all), write a line about what you did and press Commit. Every file has a diff view and a discard button.
3. Put it online. The Sync tab walks you through it: create an empty repository on GitHub (or GitLab, Codeberg, ...), paste its HTTPS address, add a personal access token, push. From then on the tab shows how many commits you have to push or pull, and Fetch, Pull and Push are one click each.
4. Clone. Clone Repository on the welcome screen or in the sidebar. Private repository? Open "Private repository? Add a token" in the dialog first, the token is what lets the browser in.
5. Branches. Create one for a rewrite, switch, merge back. Switching writes the other branch's files into your folder, so what you see in the editor is always what is on disk. Unsaved edits are kept and you are told about them.

A few things to know:

• Browsers can't speak the git protocol directly, so clone, fetch, pull and push go through a CORS proxy. The default is cors.isomorphic-git.org, run by the isomorphic-git project, and your token passes through it. You can point TeXbrain at your own proxy in the git settings, it is a tiny node app.
• The token is stored in your browser's localStorage and nowhere else. Remove it in the settings when you are on a shared computer.
• When both sides changed the same lines, nothing is touched and you get told which files, so you can sort it out in a terminal. Conflict resolution inside the editor is on the list.

Known limitations

• pdfTeX only. No XeTeX or LuaTeX, so fontspec, polyglossia, the TikZ graphdrawing library and anything else that needs them won't compile.
• No bibtex or biber. The engine doesn't ship either. Documents using biblatex get a plain thebibliography generated from the .bib file, so references show up but the citation style is ignored. Classic bibtex workflows need a .bbl in the project. A real bibtex in WASM is next on the list.
• TeX Live 2020 era. Packages are pinned to the same era as the engine's format file, so newer package versions aren't available.
• Git remotes need a CORS proxy. Browsers can't speak the git protocol directly. The default proxy is configurable, see below.
• No merge conflict resolution in the editor. A pull or merge that conflicts is aborted and tells you which files, the rest is a job for a terminal. Submodules, symlinks and git LFS are not supported either.
• Direct folder access is Chromium only. Firefox and Safari fall back to a virtual filesystem, see Browser support.

Security and privacy

Everything runs in your browser. Your files never leave your machine unless you explicitly push to a remote.

• No telemetry, no analytics, no tracking.
• No accounts, no cookies, no data collection.
• Git authentication tokens are stored in your browser's localStorage. They never touch a server I control.
• LaTeX compilation happens in a WebAssembly sandbox. There are no shell commands being executed. No pdflatex, no exec(), no spawn().
• Git operations use a JavaScript library, not CLI commands. No command injection is possible.
• The CORS proxy for git remotes is a known trade-off. By default it uses cors.isomorphic-git.org (the isomorphic-git project's public proxy). You can point it at your own if you prefer.
• Packages that aren't bundled are fetched from public TeX Live mirrors on demand. Only package filenames are sent, never your document content. Fetched files are cached locally, so this happens once per package. The fallback server can be changed or disabled entirely via the texliveMirror preference (empty string turns it off).
• LaTeX and TeX are free and open-source software. This project uses them. It doesn't redistribute or modify their source.

Tech stack

Running locally

git clone https://github.com/swimmingbrain/texbrain.git
cd texbrain
pnpm install
pnpm dev

Open http://localhost:5173 in Chrome or Edge.

Browser support

Full functionality requires the File System Access API, which is available in Chromium-based browsers (Chrome, Edge, Arc, Brave, Opera). Firefox and Safari can still use the editor with the virtual filesystem fallback, but won't be able to read/write directly to local folders.

Contributing

There is no formal process. Fork, change, open a pull request. docs/CONTRIBUTING.md has the layout of the code and what kind of help matters most right now.

License

MIT

Built by Braian Plaku