PERST is just embedded object oriented database for applications which need to deal with persistent. It is easy to use and provide high performance. The main advantage of PERST is tight integration with programming language. There is no gap between database and application data models - PERST directly stores language objects. So there is no need in packing/unpacking code, which has to be written for traditional relational databases.
Unlike many other OODBMS requires no special compiler or preprocessor. And still it is able to provide high level of transparency. PERST API is convenient, flexible and easy to use.
PERST is very compact database - only 5 thousand lines of code and 50Kb of result JAR (Java implementation). And its requirements to system resources are also very small. Also it requires completely no administration efforts. But despite to its simplicity PERST supports normal ACID transactions with very fast recovery after fault.
There are two implementation of PERST - pure Java and pure CSharp. CSharp implementation was produced from Java using Java to CSharp converter (certainly a lot manual changes are required to make it work). CSharp implementation supports more primitive types (CSharp has unsigned integer types and enums). In all other aspects two databases are completely equivalent and provides the same API.