Naven
Glossary
Data retention
How long a service keeps something after it stops needing it.
Retention is a policy, not a technical fact — the same database can be a thirty-day store or a permanent archive depending on what somebody decided. It is the part of a privacy policy most worth reading, because a service that collects little but keeps it forever has a larger exposure than one that collects more and deletes it weekly.
Deletion also has degrees. Removing a row from a live table is not the same as removing it from backups, and most policies quietly mean the first.
Where Naven stands
Naven's privacy page states what is kept and for how long in specific terms. It is written as a contract rather than as marketing, and it is updated in the same change as anything that alters what is collected.