May I self-host it?
Free to self-host, including commercially and in production.
Run it for your own applications, your customers' applications and your internal systems, at any scale, without paying anyone.
Evidence (1)
LICENSE:Additional Use Grant
Licence
What you may do with hoardDB, in plain language. The licences themselves are quoted below, unedited.
What does it not grant?
The one thing the licence does not grant is offering hoardDB itself as a database service to third parties. For that, talk to Boeger IT Sh.p.k, Tirana, Albania.
If your product is a managed hoardDB that third parties connect to and store their data in, that needs a commercial licence.
Evidence (1)
LICENSE:Boeger IT Sh.p.k
Is it open source?
The Business Source License is not an Open Source licence, and it says so itself. The Licensed Work converts to the Apache License 2.0 on the Change Date, or on the fourth anniversary of a version's first public distribution, whichever comes first.
But: Source-available is not the same as open source. Developers check this, so the site states it rather than leaving it to be discovered.
Evidence (2)
LICENSE:is not an OpenLICENSE:whichever comes first
What about the client libraries?
Client libraries live under clients/ and are Apache-2.0, so a driver you link into your own program carries no usage restriction.
But: This is a statement about the licence of a directory. clients/ holds a LICENSE and nothing else today; no client library has shipped.
Evidence (1)
clients/LICENSE:Apache License
The licences, verbatim
The server: Business Source License 1.1
Read from LICENSE in the repository at build time.
The client libraries: Apache License 2.0
Read from clients/LICENSE in the repository at build time.