This book constitutes the proceedings of the 8th International Conference on Rigorous State-Based Methods, ABZ 2021, which was planned to take place in Ulm, Germany, during June 6-11, 2021. They deal with state-based and machine-based formal methods, mainly Abstract State Machines (ASM), Alloy, B, TLA+, VDM, and Z.

Regular Research Articles.- Unbounded Barrier-Synchronized Concurrent ASMs for Effective MapReduce Processing on Streams.- Towards ASM-based automated formal verification of security protocols.- Verifying System-level Security of a Smart Ballot Box.- Proving the safety of a Sliding Window Protocol with Event B.- Event-B formalization of Event-B contexts.- Validation of Formal Models by Timed Probabilistic Simulation.- Short Articles.- Sterling: A Web-based Visualizer for Relational Modeling Languages.- Extending ASMETA with time features.- About the Concolic Execution and Symbolic ASM Function Promotion in CASM.- Towards Refinement of Unbounded Parallelism in ASMs Using Concurrency and Reflection.- The CamilleX Framework for the Rodin Platform.- Extensible Record Structures in Event-B.- Formalizing and Analyzing System Requirements of Automatic Train Operation over ETCS using Event-B.- Automatic Transformation of SysML Model to Event-B Model for Railway CCS Application.- Short Articlesof the PhD-Symposium (Work in Progress).- Formal Meta Engineering Event-B: Extension and Reasoning – The EB4EB Framework.- A modeling and verification framework for security protocols.- Formalizing the Institution for Event-B in the Coq Proof Assistant.