Auto-active verifiers provide a level of automation intermediate between fully automatic and interactive: users supply code with annotations as input while benefiting from a high level of automation in the back-end. This paper presents AutoProof, a state-of-the-art auto-active verifier for object-oriented sequential programs with complex functional specifications. AutoProof fully supports advanced object-oriented features and a powerful methodology for framing and class invariants, which make it applicable in practice to idiomatic object-oriented patterns. The paper focuses on describing AutoProof ’s interface, design, and implementation features, and demonstrates AutoProof ’s performance on a rich collection of benchmark problems. The results attest AutoProof ’s competitiveness among tools in its league on cutting-edge functional verification of object-oriented programs.