Is there any library available to query Btrieve databases without buying something from Pervasive? I'm looking to code in C# or Python.
This depends a lot on the version of Btrieve. I've been working with btrieve for a long time and have found that the best API for the old 6.15 version was in pascal. That having been said there was definately a C api around as well.
Pervasive have recently released a 6.15 ultimate patch. Using this and the C api should allow you to work effectively with older btrieve databases. It is possible for instance to build new modules for python using C.
Btrieve without Pervasive?