Replay is a tool designed for recording and replaying interpreted language runtimes to facilitate debugging and analysis by allowing users to inspect a runtime's state in a highly detailed manner. The architecture of Replay involves two main interfaces: the Recorder API, which assists in recording and replaying programs, and the Record Replay Protocol, which enables clients to interact with Replay's backend for creating, loading, and querying recordings. These interfaces support adaptation to new languages and clients, forming a platform for time travel-based debugging. When a runtime is integrated with Replay, it can be debugged using this protocol, allowing for the setting of breakpoints and evaluation of expressions at various execution points. Replay's devtools, which are open-source, utilize these capabilities to provide an efficient debugging workflow. The system employs effective determinism rather than complete determinism, which allows for analyses without requiring significant changes to virtual machines, taking advantage of existing optimizations like lazy function compilation. The tool's future potential lies in the combination of low-overhead recording with high-overhead analysis, which promises to enhance understanding of software behavior across different environments.