I get this question a lot: "Should I use OpenMark or Obsidian?" The honest answer is that they're not really competing. They solve different problems. But the confusion is understandable — both tools work with markdown files, and both live on your Mac.

Here's the comparison I'd want to read if I were choosing.

The Fundamental Difference

Obsidian is a knowledge management system. It wants you to put all your notes in a vault folder, build connections between them with [[wikilinks]], and grow a personal knowledge base over time. The killer features are the graph view, backlinks, and the plugin ecosystem. Obsidian is a destination — you open Obsidian, and you work inside Obsidian.

OpenMark is a file editor. You open a .md file from Finder or drag it onto the app, and OpenMark shows it to you beautifully rendered. You can edit it, export it, or close it. There's no vault, no graph, no plugin system. OpenMark is a tool — you use it to read and edit a specific file, then move on.

This is the central point. If you're asking "should I use OpenMark or Obsidian for my second brain," the answer is Obsidian. If you're asking "what should I use to open this README," the answer is OpenMark.

Philosophy

Obsidian's philosophy is that your notes should be connected, and that connection creates insight. It's influenced by Zettelkasten, the note-taking method developed by sociologist Niklas Luhmann. You're supposed to link ideas, build a graph of your knowledge, and let emergent structures appear over time.

OpenMark's philosophy is that markdown is already a great format, and the best thing a Mac app can do is get out of the way and show it to you. No vault, no graph, no plugins. Just your file, rendered.

Neither philosophy is wrong. They're just different.

Interface

Obsidian opens with your vault's file tree on the left, an editing pane in the centre, and an optional sidebar on the right for backlinks, tags, and plugins. It's a full-featured workspace, closer to a lightweight IDE than a text editor.

OpenMark opens to a single document. There's a Liquid Glass toolbar at the top with formatting buttons and a view toggle. The rest of the screen is your document — either rendered view or edit view. That's the whole interface.

If you've ever opened Obsidian to quickly read a README and been frustrated by the vault setup and the visual clutter, you know what OpenMark is solving.

Features

What Obsidian Has That OpenMark Doesn't

Vaults — organise hundreds or thousands of notes in linked folders
Graph view — visual map of how your notes connect
Wikilinks — [[link to another note]] syntax with auto-completion
Backlinks — see which notes link to the current note
Plugin ecosystem — thousands of community plugins for tasks, calendars, Kanban, git sync, etc.
Dataview — query your notes like a database
Mobile apps — Obsidian on iPhone and iPad, with sync
Canvas — spatial note arrangement

What OpenMark Has That Obsidian Doesn't

Liquid Glass design — native macOS Tahoe UI, feels like a first-party Apple app
Native SwiftUI — not Electron; launches instantly, uses minimal memory
Mermaid rendering (built-in) — Obsidian requires a community plugin for Mermaid
LaTeX math (built-in) — Obsidian requires a community plugin for LaTeX
Quick Look extension — preview .md files in Finder without opening any app
One-time price — $9.99 forever, no recurring costs

Performance

This is where it gets blunt: Obsidian is Electron. It starts with a noticeable delay, uses 200-400MB of RAM with a typical vault open, and doesn't feel like a native Mac app. It feels like a very good web app wrapped in a desktop container.

OpenMark is native SwiftUI. It opens essentially instantly, uses a fraction of the memory, and responds immediately. It feels like a Mac app because it is one.

If you have 32GB of RAM and don't care about launch times, this probably doesn't matter. If you're on a base model MacBook Air and you open your editor dozens of times a day, the difference is tangible.

Pricing

Obsidian is free for personal use. You pay $50/year for the Catalyst tier (early access, supporter status), and $8/month for Obsidian Sync. If you use sync, you're paying $96/year.

OpenMark is $9.99 one-time. No subscription, no account, no sync service. You buy it once and it's yours.

If you're choosing on price alone, Obsidian is cheaper if you don't need sync, and OpenMark is cheaper if you'd use sync. But I think price is probably not the deciding factor here — the use case is.

Platform

Obsidian: macOS, Windows, Linux, iOS, Android. If you write on multiple devices and platforms, Obsidian is significantly more versatile.

OpenMark: macOS only. It's explicitly built for Mac users who want a native macOS tool. No iOS app, no Windows version.

Choose OpenMark If...

You open markdown files from Finder, your IDE, or a project directory and want them to look good
You work with Mermaid diagrams or LaTeX math and don't want to configure plugins
You want a native macOS app that feels like it belongs on your Mac
You prefer tools that do one thing well rather than tools with infinite configuration
You're paying for software once and keeping it forever
You use your Mac as a Mac, not as a platform-agnostic computer

Choose Obsidian If...

You want to build a personal knowledge base or second brain
You write hundreds or thousands of interconnected notes
You need mobile apps and sync across devices
You rely on the plugin ecosystem (tasks, calendars, git, Kanban)
You need the graph view, backlinks, or wikilinks
You work across Mac, Windows, or Linux

Can You Use Both?

Yes, and many people do. Obsidian manages the vault. OpenMark opens individual files for quick reading or editing. They don't conflict — both work with plain .md files in standard markdown syntax.

Some developers use Obsidian for their notes and OpenMark when they're working with documentation files in a code project. You open the README in OpenMark, read it rendered, maybe make an edit, then close it. Your Obsidian vault is separate.

For a broader comparison of all the major markdown editors on Mac, see The Best Markdown Editors for Mac in 2026. And if you want to know more about why OpenMark was built as a native SwiftUI app specifically, read Why We Built OpenMark with SwiftUI and Liquid Glass.

Not sure which to try first? If you have a markdown file open right now, download OpenMark and open it. You'll know in about thirty seconds if it's what you're looking for.

Download OpenMark for $9.99 →