tombumd – WYSIWYG Markdown & Math Editor

Edit Markdown right in the preview, with the source kept in sync. LaTeX math, diagrams, Word/PDF export. Offline, no tracking.

tombumd (同步马) is a WYSIWYG Markdown editor that runs entirely inside your browser: offline, with no account and no tracking. Write directly in the rendered preview, the way you would in a word processor. Open the source pane beside it whenever you like, and both sides stay in sync: text, selection and caret follow each other in real time. KEY FEATURES • Twin editing: type in the preview or in the source, and content and caret stay in sync both ways. • Math: inline and display LaTeX formulas. Click any character inside a formula to edit it, open the formula palette with Ctrl+M for common symbols and templates, and get command suggestions as you type a backslash. • Equation numbering: numbers update automatically and can be referenced in the text; in-document links jump with Ctrl+Click and return with one click. • Text styling: color, font size and highlight, plus the usual bold, italic and similar formatting. • Document structure: tables, task lists, footnotes, code blocks with syntax highlighting and diagrams, with automatic heading numbers and an outline panel for navigation. • Export and sharing: save your document in common document formats or as a single self-contained web page, or copy it as rich text to paste into other editors. • Safe keeping: automatic version history, a recycle bin, and find & replace. • Bilingual interface (English / Chinese) with a built-in guide. PRIVACY • No data collection, no analytics, no ads. • Requests no browser permissions and cannot see the pages you visit. • Works offline: everything it needs is bundled in the extension; nothing is loaded from the internet. • Your documents are stored only on your device. HOW TO USE Click the tombumd button in the toolbar to open the editor in a new tab. The guide opens on first run and can be reopened at any time from the "?" button. LICENSE Free and open source (MIT License), © 2026 tombumd. Bundled third-party open-source components keep their own licenses; see THIRD_PARTY_NOTICES.md in the package.