What is Resomark
Resomark is a Mac app for reading and writing the files in real folders on your computer. Markdown files show their formatting as you write, and code, PDFs, images and web pages open right in the app too. When the AI tools you use (Claude Code or Codex, for example) change files in the same folder, Resomark marks what changed, and you decide whether to keep it or change it back.
What it does
Section titled “What it does”- Opens folders you already have. No importing, moving or converting. What you read in Resomark is the same set of files that Finder, Terminal and your AI tools see. See What is a Workspace.
- Shows formatting as you write. The line with the cursor shows the Markdown source; the rest is formatted. Tables, math and Mermaid diagrams are drawn right in the text.
- Lets you look through the whole folder. Markdown, plain text and code can be edited; PDFs, images, web pages, Office documents, audio and video can be viewed in the app. See Which files Resomark opens.
- Shows you what changed. In a folder outside Git, Resomark records every change other apps (AI tools included) make to it, and you keep or revert them one at a time, a file at a time or all at once (Plus). In a Git repository, it shows the changes you haven't committed yet. See Kinds of Workspace.
- Gets old versions back. When a file goes wrong, look through its earlier versions, compare them and restore one. See Three kinds of history.
- Search. Press ⌘P to find files, folders, Workspaces and commands by name.
- Opens folders on another machine. Over SSH, open a folder on a server or another Mac and use it like a local one (Plus).
What it doesn't do
Section titled “What it doesn't do”- There's no AI inside Resomark. It doesn't call an AI for you, and it doesn't send your files to any AI. You keep using your own AI tools; Resomark looks at the files. See Work with your AI.
- It doesn't know who made a change. It can tell whether a change is something you wrote in Resomark, but not which AI or which app made it.
- It doesn't sync. Where your files live and how they sync between devices is up to you; Resomark doesn't keep a copy of its own.
- It doesn't touch your Git. In a Git repository, Resomark only reads Git. It doesn't stage or commit for you.
Which devices it runs on
Section titled “Which devices it runs on”A Mac with Apple silicon or Intel, running macOS 15 Sequoia or later. There's only a Mac version for now. See Install and update.
Free or paid
Section titled “Free or paid”Reading, writing, browsing, search, and seeing uncommitted changes in a Git repository are free, with no time limit. Track Changes for folders outside Git, version history, Git commit history and switching, remote Workspaces and some fonts are part of Plus. Each Mac can try Plus free for 14 days, no account needed. See Free, Plus and the 14-day trial.