Why it exists

Your AI writes in Markdown. You shouldn't have to read it in a code editor.

ChatGPT, Claude, Gemini and every agent hand you the same thing at the end of a task: a .md file. Plans, briefs, calendars, checklists. Here's what happens next.

It opens as raw text

Headings, tables and lists show up as a wall of #, | and **, usually inside a tool built for code.

Ticking a box means editing

To mark one task done you hunt for - [ ] and type an x between the brackets by hand.

Pasting breaks it

Drop a draft into LinkedIn or an email and it arrives covered in ** asterisks you have to clean out.

What it does

Open the file. It's already done.

01 / Read

Opens like a finished document

Double-click any Markdown file and it opens as a typeset page with real headings, tables, callouts, footnotes, code and diagrams.

Open a whole folder, files sit in tabs on the left
Outline, quick open and a command palette
Refreshes live when your AI agent rewrites the file

A Markdown launch plan rendered as a clean document in Tomelight

02 / Tick

Click a box. It saves to the file.

Every checkbox works, including the ones inside table cells, which is how most AI content calendars and trackers are built.

Saves instantly, undo if you misclick
Mark Done stamps the whole file as finished

Checkboxes inside a Markdown table in Tomelight

03 / Write

Write like a doc, save as Markdown

Write mode feels like Google Docs: a toolbar for bold, lists, checklists, tables and links, with clean Markdown saved underneath.

Split view shows the raw file next to a live preview
Tidy fixes broken bullets and messy AI formatting in one click

04 / Copy

Copy for email, web or social. Clean.

Rich text for Gmail and Outlook, class-free HTML for WordPress and Beehiiv, or plain text for social with real bullets and zero stray symbols.

Live X (280) and LinkedIn (3,000) character counts
Paste as Markdown turns any webpage or Google Doc into clean Markdown

The Copy for menu with email, web and social options

05 / HTML

HTML opens like a real browser tab

Landing pages, reports and dashboards render with their CSS, JavaScript and fonts working, each one walled off in its own sandbox.

Edit the source and watch the page update live
Reader view strips the design for a clean article

An HTML landing page rendered inside Tomelight

06 / Images

Photos to WebP, private data gone

Pick what you're making, a blog post, Pinterest pin, Instagram post or YouTube thumbnail, and Image Studio sets the size and format for you.

Removes GPS location, camera details, EXIF, XMP and IPTC
Reads iPhone HEIC photos, downloads everything as a zip

Image Studio after shrinking 4 photos by 93 percent

07 / Notes

Sticky notes that never touch the file

Pin a note to any section. Notes live inside Tomelight, so your AI can rewrite the document and the note stays attached to its section.

08 / Highlight

Mark it up, then hand it back to your AI

Highlight what to fix, what to question and what to keep. One click turns it into feedback you paste straight into ChatGPT, Claude or Gemini.

4 colors, each with a meaning, plus a note on any highlight
Never written into the file, survives the next rewrite

09 / Side by side

Read 2 or 3 files at once

Keep the instructions on one side and the page they point to on the other. Every pane scrolls on its own, and links open right where you are reading.

Right-click a tab, drag it over, or ⌥-click a link
Optional scroll lock for comparing 2 versions

Three Markdown files open side by side in Tomelight

The details

Small app. No strings.

Nothing leaves your Mac

No account, no analytics, no update pings. Tomelight makes no network requests of its own.

4 themes

Wire by default, plus Nebula, Arcane and Parchment, or Auto to follow your Mac's light and dark mode.

Built for the keyboard

Read, Write, Split and Source on ⌘1 to ⌘4, quick open on ⌘P, everything else on ⌘K.

Export

Save any document as a PDF or a standalone HTML page.

Text zoom

From 70% to 200% with a slider, ⌘+ or a pinch on the trackpad.

Open source

MIT licensed. Read the code, file an issue or send a pull request on GitHub.

Install

Up and running in a minute.

Download the zip for your Mac. Apple Silicon for M1 and newer, Intel for older Macs.

Unzip it and drag Tomelight into Applications.

Open it once. Tomelight isn't notarized by Apple yet, so macOS says it can't verify the developer. Click Done, open System Settings → Privacy & Security, scroll down and click Open Anyway. You only do this once.

xattr -dr com.apple.quarantine /Applications/Tomelight.app

Prefer Terminal? That line does the same thing.

Make it your Markdown app. Right-click any .md file, Get Info, set Open with to Tomelight, then Change All.

FAQ

Questions

Do I need to know Markdown?

No. Read mode shows a finished document, and Write mode works like a normal document editor. Tomelight writes the Markdown for you.

Will it change my files?

Only when you change something: ticking a box, editing in Write or Split, or running Tidy. Sticky notes and highlights are stored inside the app and never written into your files.

Why does macOS warn me the first time?

Apple shows that warning for apps that aren't notarized through its paid developer program. Tomelight is open source, so you can read every line of the code it runs. Use Open Anyway once and it opens normally from then on.

Is it really free?

Yes. Tomelight is MIT licensed, with no account, trial or paid tier.

Does it work on Windows or Linux?

Not yet. Mac comes first. Windows and Linux builds are on the roadmap on GitHub.

Tomelight