Although Obsidian was indirectly supported through the standard  Markdown import, its vault structure is distinct enough to warrant its own dedicated import channel.

Import process

The first step is to obtain a .zip of your Obsidian vault:

1. First, identify where your Obsidian vault is located. The easiest way to do so is to open Obsidian and right clicking the name of the vault at the bottom of the left sidebar and then selecting Show in system explorer.
2. In your system explorer, right click the directory containing your Obsidian vault and compress it to a ZIP file (e.g. on Windows, Compress To → ZIP).

Then, in Trilium Notes:

1. In the Note Tree, right click and select Import into note.
2. In the Import from section, select Obsidian.
3. Upload the ZIP obtained in the previous step.

Supported features

The following features are preserved by Trilium during the import process:

• Folder hierarchy is preserved.
• Basic Markdown formatting (bold, italic, underline, strikethrough, headings).
• Specific Obsidian formatting (highlighting).
• Lists
• To-do lists
• Images and  Attachments
  • Non-Markdown files in the Vault are treated as attachments by default if they are referenced by at least one note.
  • Otherwise, they will be imported as File notes.
• Transclusions are converted to Include Note or  Images (depending on type).
• Math Equations (inline or block)
• Code blocks, with a best-effort attempt to restore the language.
• Links between pages are converted to Internal (reference) links.
• Callouts are converted to Trilium's Admonitions.
  • Obsidian has many more types of callouts (tldr, question, attention), these are all mapped to one of Trilium's existing admonition types (e.g. Note, Tip, Important).
  • Custom titles are kept and shown as a bold line at the top of the admonition, since there is no concept of admonition title in Trilium.
  • Foldable callouts are imported expanded and without a fold marker.
• Notes created by the Excalidraw community plugin for Obsidian are converted to Canvas (same underlying technology).
  • Note that custom features introduced by that plugin will not be supported.
• Modification date is preserved via the information obtained from the .zip archive, creation date is not recoverable so it's kept the same as the modification date.

Properties

Properties are Obsidian's equivalent of Promoted Attributes. One of the core differences between the two is where the property information is stored (i.e. name and type): in Obsidian everything is stored at vault level and shared across all notes, whereas in Trilium each page can have individual promoted attributes, shared through Templates or  Attribute Inheritance.

Another important difference is that promoted attributes in Trilium are always displayed, even if empty. In Obsidian, these are simply suggested when creating a new property.

To reconcile all these differences, properties are converted to  Promoted Attributes at note level.

The following note types are supported:

Special properties

Obsidian has a few reserved property names, which are treated differently in Trilium as well:

• tags, where every tag is turned into its own label (e.g. #one, #twowhen tags: [ one, two ]).
• aliases are simply mapped to individual #aliaslabels
• cssclasses, publish, permalinkare ignored.

Limitations

• Comments (%% syntax) are simply stripped.
• Obsidian bases functionality is not preserved.
  • The closest equivalent in Trilium would be Collections but they work fundamentally different because bases don't store particular notes, they act more like a Saved Search with a collection view.
  • Since the base query format is quite different to Trilium's Search syntax, it's unlikely they'll ever be supported.
  • When a base is encountered, it is simply ignored from the import.
• Canvases are not imported.
  • Theoretically they could map to either Canvas or Relation Map but they are too different to reconcile.
• Links
  • Links to a specific heading in another note will still point to the right note, but the heading anchor will be dropped.
  • Dangling links (pointing to a note that doesn't exist) and ambiguous links (same base name in 2+ notes) are unwrapped to plain text.