Support group https://groups.google.com/forum/#!forum/linqdb
Linqdb is free for non-commercial use.
For commercial use pricing is 1250€ per server. This buys unlimited instances of Linqdb on one server. This also buys next three releases of Linqdb.
Purchase is available through Paypal. Paypal's purchase receipt is
*2018-08-04 Switch to Rocksdb (more reliable), in-memory indexes, group-by statement, v2.1.9. Not backward compatible with previous version's data format
*2017-07-30 Bug fixes, v 1.7
*2017-07-05 Bug fix, v 1.6
*2017-04-21 Multiple bug fixes, v 1.01. Not backward compatible with previous version's data format
*2017-04-10 Initial release, v 1.0
*Make server as service and add support for multiple dbs.
*Saving and working on complex properties, i.e. db.Table<Order>().Where(f => f.Adress.City == 'Berlin').SelectEntity()
*Replication, seamless corruption/failure recovery by switching to replication node