Both have an official MCP. They are reachable differently.
This is an unusually close comparison, because Tana is one of the few note tools with an official, vendor-built MCP server. It supports read and write: an assistant can search nodes, read them, and run mutations like tagging or setting field content. If you want a structured outliner with a real MCP, Tana is a serious option.
The difference is where the server lives. Tana's MCP runs locally, on your machine, while the desktop app is open. Hjarni's MCP is hosted at a remote endpoint. That single fact drives most of the practical tradeoffs below.
Local-first versus hosted
A local MCP server is great when you are working at your own desk with the app running. Your data stays on your machine, and the connection is direct. The cost is reachability: a cloud assistant cannot call a server that only exists on your laptop, and nothing responds when the app is closed or you are on another device.
Hjarni runs the server for you. Because the endpoint is hosted, Claude, ChatGPT, and other MCP clients can reach your notes from any device, with no app to keep open. The tradeoff is the mirror image of Tana's: less local control, more always-on reach.
Tana's MCP is local-first and structured. Hjarni's is hosted and always reachable. Neither is wrong; they optimize for different setups.
Structured nodes versus plain Markdown
The other real difference is the data model. In Tana, everything is a node, and supertags turn nodes into typed objects with fields and views, closer to a database over an outline. That structure is powerful if you want to model your knowledge precisely.
Hjarni is plainer on purpose: Markdown notes in folders, with folder-level AI instructions. There is less structure to maintain, and the notes stay simple text you own. Which is better depends on whether you want a typed outliner or a clean note store.
When Tana is the better fit
If you want a structured, database-like outliner with supertags and typed fields, and you are comfortable keeping the desktop app open for its local MCP, Tana is an excellent choice. Power users who think in nodes and views often prefer exactly that.
When teams pick Hjarni instead
The case for Hjarni is reach and simplicity. A hosted MCP means your notes answer from any device and from cloud AI without running an app, and plain Markdown means less structure to maintain. If those matter more than typed fields, Hjarni fits better.
Hjarni notes are plain Markdown you own, exportable as a ZIP anytime, hosted in the EU.