Transformium

Copy a table.
Get CSV, Markdown or JSON.

Select a table in Numbers, Excel, Mail or Safari and press one shortcut. It's on your clipboard as clean CSV, a Markdown table or JSON, ready to paste. No exporting, no stray files, no tidying up.

Mac app — coming soon

Coming soon. Transformium is finished and going through Apple's signing and notarization — the security check that lets it open on your Mac without a warning. Download links will appear here as soon as that's done; until then there's nothing to install. See Availability. Version 1.0.0.

About 4× faster than exporting a CSV

Numbers and Excel will give you CSV — as a file. Getting the text onto your clipboard means exporting, finding the file, opening it in a text editor and copying it back out. Transformium does all of that with one shortcut.

  • The usual way

    about 24 seconds

    1. File → Export To → CSV…
    2. Click Save…, then Export
    3. Switch to Finder and open the folder you saved to
    4. Right-click the file → Open With → TextEdit (double-clicking just opens it in Numbers again)
    5. Select all, copy
    6. Later: delete the file you only made to copy from

  • With Transformium

    about 6 seconds

    1. Select the table
    2. Press ⌃⌘X (Control-Command-X)

    That's it. CSV on your clipboard, and no file left behind.

That's about 18 seconds back every time. Convert ten tables a working day and it comes to roughly 15 minutes a week.

For Markdown and JSON there isn't even a slow way: neither Numbers nor Excel exports them. The usual fallback is pasting your data into a converter website. Transformium does it on your Mac, and your data stays there.

How we worked these numbers out

We used the Keystroke-Level Model, a standard method from human–computer interaction research for estimating how long a task takes. Each step is broken down into clicks, keystrokes, mouse movements and brief pauses to think, and each of those has a published average time (Card, Moran & Newell, 1980; Kieras, 2001). The steps were checked against Numbers 15.3.

Transformium's own part is measured. Converting a 200-row table takes under a hundredth of a second on our M4 Max, and a 2,000-row table under a twentieth. We counted half a second anyway.

Every judgement call went the usual way's way: someone who knows every menu by heart and never hesitates, a document with only one table, short waits for each dialog and for TextEdit to open, and no time for cleaning up the exported file. Take every pause to think out of both and Transformium is still more than 4× faster. If the table is already selected, it's over 9× faster.

Ten tables a day is only an example. Multiply the seconds saved by however many you convert.

Works wherever your tables are

Numbers, Excel, Mail, Safari: if you can select a table and copy it, Transformium can convert it. There's nothing to set up for each app.

  • You get what you see. A cell showing $1,234.56 comes out as $1,234.56, not 1234.56 — the same as Numbers' own CSV export.
  • Awkward cells come through intact. Merged cells, and cells containing commas, tabs or line breaks, don't break the table.
  • Output that other tools accept. Standard CSV (RFC 4180) that imports cleanly into spreadsheets and databases, Markdown tables with neatly aligned columns, and JSON with one record per line, named by your column headings.
  • It works in reverse too. Copy a Markdown table or some CSV text and turn it into another format, or select a CSV, JSON or XML file in Finder and convert it without opening it.
  • Tables that were never meant to be data. The bordered tables a terminal, a chat transcript or an AI assistant prints — drawn with ┌─┬─┐ or +---+---+, or the style psql uses — are read as tables, not as text. Copy one and paste it into a spreadsheet.

Two ways to use it

One app. It works with anything you can copy, and it brings a Safari extension for tables on web pages with it — one download, nothing else to install.

  • The Mac app

    Adds Copy Table as CSV, as Markdown and as JSON to the Services menu in every app, each with its own keyboard shortcut. Select, press, paste. It also comes with a command-line tool for Terminal and scripts.

  • The browser extension

    A toolbar button, a right-click menu and keyboard shortcuts. It lists every table on the page by name and highlights the one you point at, so you always copy the right one. It also reads Markdown and bordered tables in code blocks, and XML or JSON that the browser is showing. Included in the Mac app for Safari; available separately for Chrome and Firefox. Safari 18.4 or later.

Keyboard shortcuts

These are the defaults. You can change any of them in System Settings → Keyboard → Keyboard Shortcuts → Services.

  • ⌃⌘X — Control-Command-X — Copy Table as CSV
  • ⌃⌘K — Control-Command-K — Copy Table as Markdown
  • ⌃⌘J — Control-Command-J — Copy Table as JSON
Why these shortcuts?

Nothing built into macOS uses them, so they won't clash with shortcuts you already rely on. Shift-Command combinations are crowded by comparison — ⇧⌘C is already Finder's Computer, for one.

If another app you use does claim one of them, that app's shortcut wins inside it. Pick a different combination in System Settings and you're set.

About the “control your Mac” permission

macOS will ask whether Transformium may “control your Mac”. That's Apple's standard wording for the Accessibility permission — every app that asks for it gets the same sentence — and it sounds much broader than what Transformium does with it.

It uses it for one thing: pressing ⌘C for you in the app you're working in, so that a single shortcut both copies and converts. It doesn't read other apps' windows, doesn't watch what you type, and does nothing at all between shortcuts. You can allow it, or change your mind later, in System Settings → Privacy & Security → Accessibility.

Rather not allow it? Everything still works. Press ⌘C yourself first, then the shortcut.

For Terminal and scripts

The Mac app includes a transformium command. It converts the clipboard or files, stacks files with matching headers into one table, and does exactly what its options say — it ignores the app's settings, so a script gives the same result on every Mac. 

transformium                 # convert the clipboard in place, as CSV
transformium --markdown      # ...as a Markdown table
transformium --json          # ...as JSON, one record per line
transformium --stdout        # print instead
transformium report.csv      # convert files instead of the clipboard
transformium jan.csv feb.csv # ...stacked, if their headers match
transformium --list-types    # what did that app actually put on the clipboard?

Your tables never leave your Mac

No account, no analytics, no telemetry — not settings you can switch off, but things that simply aren't there. Your tables are converted on your Mac and go straight back onto your clipboard.

The app sends exactly one kind of request: an update check, which asks transformium.app whether a newer version exists. It asks your permission the first time it runs, you can turn it off, and it sends nothing about you, your Mac or anything you've converted.

Read the privacy note. It's one page, and it covers this website too.