Open source

Metrics Book is open source under the Apache License 2.0, copyright 2026 Enum Studio ApS. That covers everything in the repository: the API, the CLI, the job runner, the templates, the stack definition and these docs.

There is no paid tier and no hosted version. You run Metrics Book on your own server, and you own the data and the definitions in it.

The one part that is not open

The semantic layer runs on anfra, from Holistics. anfra’s compiler and query runner are closed binaries. The rest of anfra’s tooling, and everything Metrics Book adds around it, is open.

The stack reaches anfra through one module, SemanticEngine, and only through an allowlist of operations. If anfra stops being the right choice, replacing it means changing that one module, not the whole stack.

The open-source tools inside

Tool	What it does here
dlt	loads data from your sources
dbt	transforms it into marts
DuckDB	stores it, by default
Postgres	holds sign-in, audit and the catalog, and can be the warehouse
Cerbos	decides who may see what
Better Auth	signs people, agents and service accounts in
Hono	serves the API and the connector

Who maintains it

Metrics Book is built and maintained by enumstudio. Enum Studio ApS is the company behind it and holds the copyright, as the NOTICE file says. Martin Brummerstedt decides what goes into the core. Contributions are welcome: Contributing says how.

Report a vulnerability privately, as the security policy describes.