GAPT is a proof theory framework developed primarily at the Vienna University of Technology. GAPT contains data structures, algorithms, parsers and other components common in proof theory and automated deduction. In contrast to automated and interactive theorem provers whose focus is the construction of proofs, GAPT concentrates on the transformation and further processing of proofs. You can also use Prover9, Vampire, EProver, and lots of other provers instead of the built-in Escargot prover, if you have them installed. There are many more examples in the user manual, and you can look into the API documentation for reference as well.