fern-app 0.6.3

An open files and open source alternative to Notion and AppFlowy for tasks and pages viewing and management.

Fern

Offline-first desktop app for vaults, databases, and pages — an open-source alternative to Notion/AppFlowy. Native PySide6 UI; data lives as markdown + frontmatter in local folders.

• Vaults → folder with a Databases/ subfolder; each database is a subfolder of markdown pages.
• Pages → one .md file per page (YAML frontmatter for id, properties; body = content).
• Properties → schema in schema.json per database; boolean/string (and more) with table + editor UI.

Install

pip install fern
# or
uv add fern

Run

fern

Open a folder as a vault; create and edit pages and properties from the UI.

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Technical

Item	Detail
Python	3.13+
GUI	PySide6
Data	Markdown + YAML frontmatter, schema.json per database
Build	Hatchling (pyproject.toml)
Dev / test	uv, pytest, pytest-cov

Architecture (clean / hexagonal):

• Domain — entities (Vault, Database, Page, Property, PropertyType), repository ports (abstract).
• Application — use cases only (open vault, list DBs/pages, CRUD page, add/remove/update property, update property order, update page property).
• Interface adapters — repository implementations: filesystem vault, vault DB (markdown + schema.json), in-memory/markdown page repos.
• Infrastructure — PySide6 views and components, controller, factory wiring adapters into use cases.

Layout: src/fern/ → application/, domain/, interface_adapters/, infrastructure/.

Development:

uv sync --all-groups
uv run pytest tests/unit_tests/ --cov
uv build

Unit tests target application, domain, and interface_adapters (100% coverage enforced). Coverage scope: .coveragerc → fern.application, fern.domain, fern.interface_adapters.

CI/CD (GitLab):

• Merge requests: version must differ from target branch; CHANGELOG.md must have ## [x.y.z] for that version; unit tests (uv + pytest + cov); package build.
• Push to default branch: build → publish to GitLab Package Registry and PyPI (twine); create release and tag v<x.y.z> via Releases API; build and deploy documentation to GitLab Pages. PyPI requires CI variable PYPI_API_TOKEN.

Documentation: Architecture and developer guide built with MkDocs + Material, hosted on GitLab Pages. Run locally with uv run mkdocs serve.

Versioning: Semantic Versioning; changelog format Keep a Changelog. Bump version in pyproject.toml and add a changelog section for each release.