Tabelo

One table, seven views, zero copy-and-paste between them.

Hi! Tabelo is a small table editor for the moments when a spreadsheet is too much, but hand-editing pipes and commas is no fun either. Change a cell in the visual table and the Markdown updates. Fix the CSV and the table updates. Open up to four views and they all stay in sync.

Everything runs in your browser. No account, no server, no upload.

→ martonpaulo.github.io/tabelo

---

Here is the whole idea

These are not separate files. They are the same table:

Grid

Name	Role	Active
Inez	Designer	Yes
Mark	Developer	No

Markdown — alignment and all

| Name  | Role      | Active |
| :---- | :-------: | -----: |
| Inez  | Designer  | Yes    |
| Mark  | Developer | No     |

CSV

Name,Role,Active
Inez,Designer,Yes
Mark,Developer,No

Jira

||Name||Role||Active||
|Inez|Designer|Yes|
|Mark|Developer|No|

Go through CSV or Jira and back and those :---: alignment markers are still there. Those formats cannot express alignment, so Tabelo quietly remembers it.

What it does

• Arrange the workspace. One to four panes, with each view available only once. Open the floating Tabelo button for files, layouts, undo, redo, and the GitHub link.
• Seven views. Visual grid, Markdown, CSV, TSV, HTML source, Jira table syntax, and a rendered preview. Every one stays in sync with the others.
• Edit visually. Cells, headers, rows, columns. Insert above, below, left, right. Delete, duplicate, reorder, resize, select ranges, clear. Right-click anything for the actions that apply to it.
• Edit the source. Markdown, CSV, TSV, HTML, and Jira all have syntax highlighting. Errors get a red underline, warnings a yellow one; hover either to see the explanation.
• Never lose a cell. A value with a line break in it survives CSV → Markdown → CSV byte-exact. Markdown can't hold a raw newline, so Tabelo escapes it and unescapes it back. Same for pipes.
• Type freely. While your Markdown is half-written and invalid, the grid keeps showing your last working table instead of collapsing. The underline tells you what needs fixing.
• Paste anything. Spreadsheets, web tables, Markdown, CSV, TSV, Jira syntax, a plain column of text. Tabelo works out which it is.
• Download anything. Markdown, CSV, TSV, HTML, or Jira, with the right extension and MIME type.
• Nothing to save. Your table stays in browser storage and comes back when you return. Starting a new table asks before clearing real work.
• Works offline. A service worker caches the app on your first visit. No install prompt, no app store, nothing to accept.

What it deliberately doesn't do

No formulas, extra sheets, charts, macros, pivot tables, accounts, cloud sync, collaboration, or analytics. Tabelo is happiest staying small.

Keyboard

Both hands stay where they are.

Keys	What happens
Arrows	Move between cells
Shift + arrows	Extend the selection
Enter / F2	Edit the focused cell
Any character	Replace the cell and start typing
Enter while editing	Commit, move down
Shift Enter while editing	Line break inside the cell
Tab / Shift Tab	Next / previous cell
Alt + arrows	Move the row or column itself
Backspace	Clear the selected cells
⌘ Backspace	Delete the selected rows or columns
⌘ Enter	Add a row below
⌘ A	Select everything
⌘ Z / ⌘ ⇧ Z	Undo / redo

Undo is layered: inside a source view it undoes your keystrokes, and once that history runs out it keeps going through the table's own history. One timeline underneath, native behaviour on top.

Every shortcut also has a menu entry, so nothing is reachable only by keyboard.

Run it locally

Requires Node.js 24+ and pnpm 11+.

pnpm install

pnpm dev

Then open http://localhost:3001.

Command	What it does
pnpm dev	Dev server
pnpm build	Production build
pnpm test	Unit tests
pnpm test:e2e:install	Install Chromium and Firefox for browser tests
pnpm test:e2e	Browser tests in Chromium and Firefox
pnpm check-types	TypeScript
pnpm lint	Biome check
pnpm check	Biome check, writing fixes

A quick look under the hood

React 19, Vite, TanStack Router, Tailwind v4, shadcn/ui on Base UI, CodeMirror 6 for source views (lazily loaded), Papa Parse for delimited formats. Scaffolded with Better-T-Stack. The grid is hand-built — no grid library.

One idea holds the whole thing up: there is a single canonical table document, and every format is a parser and serializer around it. No text format is ever the source of truth. That is what makes round trips safe.

Formats and views live in two small registries. Adding a format is one file plus one registry line, and it becomes editable, downloadable, importable, and pasteable everywhere at once.

The decisions worth reading before you change anything:

• Derive every representation from one table document — and why a CRDT wouldn't have helped
• Escape Markdown losslessly instead of flattening
• Layer text-editor undo on top of a document timeline
• Build an accessible DOM grid instead of adopting a spreadsheet component
• Describe formats and views in registries, not in the core
• Offer preset workspace layouts instead of free slot assignment

docs/design-system.md is binding for anything visual, CONTEXT.md defines the vocabulary, and AGENTS.md holds the working agreements.

Privacy

Your data never leaves your browser. There is no backend, no account, and no telemetry of any kind. The document lives in localStorage on your machine. Clear your browser storage and it is gone — there is no copy anywhere else, including with us.

Honest limitations

• Built for tables up to a few hundred rows. There is no virtualization, on purpose. Paste 50,000 rows and it will warn you rather than pretend.
• Cell values are opaque text. Tabelo never guesses types, never coerces a number, never reformats a date. What you typed is what is stored.
• Markdown output contains <br> where a cell has a line break. That is the price of not losing the line break. Strict CommonMark renderers that escape raw HTML will show it literally.
• One document at a time. Four views of it, but one table.
• Reordering is keyboard and menu, not drag. This was a choice: the keyboard path works for everyone, and drag-only reordering does not.
• Layouts come from a preset list. Eight arrangements of a 2×2 grid, not a free-form slot editor. That covers every rectangular tiling and keeps the control to one click.

License

MIT © 2026 Marton Paulo