Serverless computing (e.g., AWS Lambda) was initially designed for event-driven applications, where each event handler is guaranteed to complete within a limited time duration. Kappa aims to enable general purpose, parallel computation on serverless platforms. To do this, Kappa provides a continuation-based checkpointing mechanism that allows long-running computations on time-bounded lambda functions; and, a message-passing concurrency API for easily expressing parallelism and exploiting the elasticity of serverless platforms.