leanCoP is a very compact theorem prover for classical first-order logic, based on the connection (tableau) calculus and implemented in Prolog. leanCoP 2.0 enhances leanCoP 1.0 by adding regularity, lemmata, and a technique for restricting backtracking. It also provides a definitional translation into clausal form and integrates “Prolog technology” into a lean theorem prover. ileanCoP is a compact theorem prover for intuitionistic first-order logic and based on the clausal connection calculus for intuitionistic logic. leanCoP 2.0 extends the classical prover leanCoP 2.0 by adding prefixes and a prefix unification algorithm. We present details of both implementations and evaluate their performance.