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Notesium

Free plan Open source APILinuxMacWebWindows

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Notesium's own site

What Notesium is

Notesium organizes notes as linked Markdown files in one local folder, with a focus on Zettelkasten and Evergreen note-taking. In its web editor, typing `[[` opens a finder for adding a link, and saved notes connect in both directions. The Finder searches the full text of notes, while an interactive graph displays their relationships with filtering, previews, zoom, and layout adjustments. Its editor includes Markdown syntax highlighting, section folding, table formatting, and Vim mode emulation. A Vim and Neovim plugin uses the CLI to find and preview notes. The local REST API can create, update, delete, retrieve, and list notes, but the maker describes it as unstable and without explicit versioning. API changes require starting the daemon with the `--writable` option. Notesium is free for personal and business use and is open source under the MIT License. It supports Linux, macOS, Windows, web, and API access, with offline access. The maker describes uses including journaling, research, writing, and workout tracking.

Who it suits

Notesium may suit people building personal notes, knowledge bases, research collections, journals, or writing projects. Its local Markdown storage and Vim/Neovim plugin may appeal to users who want notes accessible through those tools.

What it does well

  • Free for personal and business use.
  • Notes are stored as local Markdown files.
  • Bidirectional links and a searchable Finder.
  • Graph view shows note relationships.
  • Offline access is listed.

What to know first

  • The REST API is described as unstable.
  • API has no explicit versioning.
  • API writes require the daemon's `--writable` option.

Plans

PlanBilled and limitsPrice
FreeFree for personal and business use · Open source · MIT License · Linux, macOS and WindowsFree

As notesium.com lists them, read 15 Oct 2026. The maker's own page has the final word.

Getting started

  1. Visit the Notesium website.
  2. Choose an installation route for Linux, macOS, or Windows, or use the web interface or API.
  3. Verify downloaded binaries against the published SHA-256 checksums, as the installation guide instructs.
  4. Keep notes in a single local folder as plain Markdown files.
  5. Use `[[` in the web editor to find and insert links between notes.
  6. For API note creation, updates, or deletion, start the daemon with `--writable`.
  7. Install the Vim or Neovim plugin to find and preview notes through the CLI.

Verdict

Notesium brings linked Markdown notes, full-text search, and a relationship graph together in a free tool. Its API caveats matter if you plan to build on API-based workflows.

Questions

How much does Notesium cost?

The Free plan costs nothing. It is free for personal and business use.

Is Notesium open source?

Yes. It is open source under the MIT License.

Which platforms does Notesium support?

It supports Linux, macOS, Windows, a web interface, and API access.

Can Notesium work offline?

Yes. Offline access is supported.

Can I edit notes through its API?

The local REST API can create, update, and delete notes when the daemon is started with `--writable`. The API is described as unstable and has no explicit versioning.

What kinds of work is Notesium intended for?

The maker describes personal notes, knowledge bases, journaling, research, book writing, and workout tracking as use cases.

Facts from Notesium's own pages

API
The local REST API uses JSON and exposes endpoints to create, update, delete, retrieve and list notes. · notesium.com, 15 Oct 2026
API data model
The documented note object includes filename, title, label status, incoming and outgoing links, timestamps, counts, path and content. · notesium.com, 15 Oct 2026
API stability
The API documentation calls the interface unstable and says it has no explicit versioning. · notesium.com, 15 Oct 2026
API write control
API writes are forbidden unless the daemon is started with the --writable option. · notesium.com, 15 Oct 2026
Bidirectional links
Links create outgoing and automatically discovered incoming relationships between notes. · notesium.com, 15 Oct 2026
CLI
Notesium includes a command-line interface with list, links, lines, finder, statistics, web and version commands. · github.com, 15 Oct 2026
Custom URI
Notesium documents a custom notesium:// URI protocol for opening notes and actions. · notesium.com, 15 Oct 2026
Editor
The embedded web editor supports Markdown syntax highlighting, section folding, table formatting, and Vim mode emulation. · notesium.com, 5 Oct 2026
File naming
Note filenames use deterministic eight-character hexadecimal identifiers derived from Unix epoch time. · notesium.com, 15 Oct 2026
Graph
An interactive force graph visualizes note relationships and supports search filtering, preview, zoom, and layout adjustments. · notesium.com, 5 Oct 2026
Graph view
An interactive force graph visualizes relationships and supports filtering, previews, zooming and layout-force controls. · notesium.com, 15 Oct 2026
Installation
Prebuilt binaries are provided for Linux, macOS and Windows, with SHA-256 checksum verification instructions. · notesium.com, 15 Oct 2026
Integrations
Notesium provides a Vim/Neovim plugin that uses its CLI for note finding and preview. · notesium.com, 5 Oct 2026
Intended users
The maker describes use cases including personal notes, knowledge bases, journaling, research, book writing, and workout tracking. · notesium.com, 5 Oct 2026
Knowledge models
The product is designed for Evergreen notes, Zettelkasten workflows and personal knowledge management. · notesium.com, 15 Oct 2026
Labels
A note with a one-word title is treated as a label and can organize linked notes into a taxonomy. · notesium.com, 15 Oct 2026
Latest release
GitHub lists v0.6.5 as the latest release, published 20 July, with Vim/Neovim improvements and rewritten web tab management. · github.com, 15 Oct 2026
License
The repository identifies the project as MIT licensed. · github.com, 15 Oct 2026
Linking
Typing `[[` in the web editor opens a finder to insert a link, and saved notes are linked bidirectionally. · notesium.com, 5 Oct 2026
Link insertion
Typing double brackets in the web editor or Vim integration opens a finder that inserts a Markdown link. · notesium.com, 15 Oct 2026
Local deployment
The embedded web interface is self-contained and runs locally on the user's machine. · notesium.com, 15 Oct 2026
Maker
The site credits Alon Swartz in its copyright notice. · notesium.com, 15 Oct 2026
Performance
The maker reports a 6.3 MB Linux build and 11.4 MB system memory for its web and API setup, noting that actual performance varies by system and usage. · notesium.com, 5 Oct 2026
Performance claim
The official site reports an example Linux binary size of 6.3 MB, 11.4 MB total memory for web/API and 0.008 seconds for a sample CLI operation. · notesium.com, 15 Oct 2026

Where Notesium stands on Freedom251

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