Nodum vs Obsidian
The open-source Obsidian alternative that runs in your browser
Nodum is an open-source alternative to Obsidian that runs in a browser instead of as a desktop app. It uses the same wikilink syntax, the same backlinks and the same plain-markdown files, adds a GPU-rendered knowledge graph, and is MIT licensed — so you can read every line, self-host it, and export your vault as ordinary .md files at any time.
What Obsidian is
Obsidian is a local-first markdown knowledge base: a desktop and mobile app that reads a folder of plain .md files on your own disk, links them with [[wikilinks]], and draws the result as a graph. Its plugin ecosystem is the largest in this category by a wide margin, and the app itself is free. It is also closed-source — the vault format is open, the program is not — and it is not a web application, so a machine you cannot install software on is a machine you cannot use it on.
Side by side
| Property | Obsidian | Nodum |
|---|---|---|
| Licence | Proprietary. The file format is open; the application is not | MIT — the whole stack, frontend and backend |
| Hosting | Local-first desktop and mobile app; optional paid Sync service | Hosted at nodum.md, or self-hosted with one Docker Compose command |
| Your notes are | Plain markdown files in a folder on your own disk | Plain markdown files, exported as a folder-true zip whenever you ask |
| Linking | [[wikilinks]], aliases, embeds, block references, heading links | [[wikilinks]], [[path/Note]], [[Note|alias]], ![[embeds]] — Obsidian syntax |
| Graph | Global and local graph view, with groups and filters | Global and local force-directed graph, GPU-rendered on WebGL2 |
| Pricing model | Free for personal and commercial use; Sync and Publish are paid add-ons | Free and open source; self-host at your own infrastructure cost |
| Platforms | macOS, Windows, Linux, iOS, Android — no browser version | Any modern browser, desktop and mobile; installable as a PWA |
| Getting out | Nothing to export: the files are already yours, on your disk | Vault zip of .md files, plus a REST API and an MCP server |
Where each one actually wins
The left-hand column is the honest part. If none of it applies to you, the switch is probably worth making; if several do, it probably is not.
What Obsidian does better
- A plugin ecosystem of well over a thousand community plugins, plus themes — nothing else in this category is close, and Nodum's sandboxed plugin API is deliberately narrower.
- It works with no network at all. Nodum needs a server it can reach, even if that server is a Raspberry Pi in your cupboard.
- Your notes are already files on your own disk, which is the strongest data-ownership story anyone can offer.
- Mature native mobile apps, offline editing included.
- Years of polish and a large community writing about workflows, templates and setups.
What Nodum does better
- It is genuinely open source — MIT, frontend and backend — so you can audit it, fork it, or run it forever regardless of what the project does next.
- It runs in the browser. A locked-down work laptop, a Chromebook, a borrowed machine and a phone all get the same vault with nothing installed.
- Sync is not an add-on. The server is the vault, so every device is current by construction, with no subscription attached.
- Real-time collaborative editing on a note, with presence — Obsidian has no first-party equivalent.
- Publishing a vault as a public site is built in rather than a separate paid product.
- An MCP server with 36 tools, so Claude Code, Claude Desktop or Cursor can read and write your vault directly.
- An AI assistant that works on your vault using your own API key, encrypted at rest — no per-seat AI upsell.
So — switch, or stay?
Switch to Nodum if…
- You want to open your notes on any machine, without installing anything.
- You care that the software itself is open source, not only the file format.
- You are paying for Sync, or Publish, and would rather run the whole thing yourself.
- You want two people editing one note at the same time.
- You want an AI assistant, or an MCP client, working directly against your notes.
Stay on Obsidian if…
- You depend on specific community plugins — Dataview, Templater, Excalidraw. That ecosystem is Obsidian's moat and Nodum does not replicate it.
- You work offline for long stretches, on a plane or in the field.
- You want your notes to exist as files on your own filesystem at all times, with no server in the picture.
Moving your notes across
- 1. Export your Obsidian vault. Zip your vault folder exactly as it sits on disk. Keep the folder structure — Nodum resolves path-style wikilinks like [[projects/Note]] against it.
- 2. Create a Nodum vault. Sign up at nodum.md or start your own instance with ./compose.sh prod up -d --build, then create an empty vault.
- 3. Import the zip. Settings → Vault → Import. Nodum unwraps a redundant root folder, detects .obsidian config directories, and treats .md, .markdown and .txt as notes. PDFs come in as attachments plus a note of their extracted text.
- 4. Check the links resolved. Links are resolved across the whole import batch rather than file by file, so [[Note]] references to files later in the zip still land. Open the graph: anything still a ghost node was an unresolved link in Obsidian too.
- 5. Keep your exit open. Export the vault whenever you like and you get a folder-true zip of .md files back — the same thing you put in.
Nothing about the import is one-way. Nodum's export is Obsidian-compatible, so going back is the same operation in reverse.
Obsidian and Nodum: common questions
Is Obsidian open source?
No. Obsidian is a proprietary, closed-source application. Its vault format is open — plain markdown files in a folder — but the program itself is not, and its source code is not published. Nodum is MIT licensed end to end, so both the format and the software are open.
Is there a web version of Obsidian?
Obsidian has no official browser version; it ships as a desktop and mobile application. Nodum is a web-native knowledge base built on the same ideas — CodeMirror 6 editor, [[wikilink]] syntax, backlinks and a graph view — so it runs in any modern browser with nothing installed.
Can I import my Obsidian vault into Nodum?
Yes. Zip your vault folder and import it from Settings → Vault → Import. Nodum resolves wikilinks across the whole batch, handles nested folders and path-style links, recognises .obsidian config folders, and imports .md, .markdown and .txt files. Export gives you a folder-true zip of markdown back.
Does Nodum support Obsidian plugins?
No, and the project says so plainly rather than implying otherwise. Obsidian plugins are written against Obsidian's own Node-level API; Nodum's plugin API is capability-scoped and runs inside an opaque-origin sandboxed iframe, which is a deliberately different and narrower contract. If a specific plugin is central to how you work, stay on Obsidian.
Is Nodum free?
Yes. Nodum is free and open source under the MIT licence. You can use the hosted instance at nodum.md or run your own with one Docker Compose command, in which case your only cost is the server you run it on.
Before you move anything
Whatever you decide, run this once. It takes ten minutes and it is the difference between a migration and an incident.
- Export from Obsidian first, and keep that export somewhere safe.
- Import a copy into a throwaway Nodum vault, not your main one.
- Open the graph and look for ghost nodes — those are links that did not resolve.
- Export the Nodum vault and diff it against what you put in.
- Only then delete anything.
Other comparisons
Every comparison is on the alternatives index, and the glossary defines the vocabulary these pages use.
Bring your Obsidian notes with you.
Import a zip, look at the graph, export it again. Nothing about it is one-way.