neverthrow and Effect represent two distinct approaches to error handling in TypeScript applications. neverthrow is a focused, lightweight library that provides Result types (Ok/Err) for explicit error handling, offering a minimal API surface that integrates easily into existing codebases. Effect is a comprehensive functional effect system that treats errors as first-class citizens within a broader framework encompassing dependency injection, resource management, and concurrency primitives.
This comparison matters because choosing between them determines not just your error handling strategy, but your application's architectural approach. neverthrow targets teams seeking type-safe error handling without adopting full functional programming paradigms—ideal for library authors and teams gradually improving error visibility. Effect appeals to teams committed to functional programming who need integrated solutions for complex async workflows, resource safety, and dependency management, accepting the steeper learning curve and larger bundle size in exchange for comprehensive capabilities.
Choose neverthrow for most TypeScript projects requiring better error handling without architectural upheaval. It delivers 80% of the error handling benefits with 20% of the complexity, making it ideal for library development, gradual codebase improvements, or teams without deep functional programming experience. The minimal bundle size and straightforward adoption path allow you to introduce type-safe error handling incrementally while preserving existing patterns. neverthrow excels when your primary goal is making error cases explicit in function signatures without restructuring how your application manages effects.
Choose Effect when building complex applications where error handling is just one piece of a larger architectural puzzle requiring dependency injection, structured concurrency, and resource safety. Effect justifies its complexity in domains like backend services with intricate async workflows, applications requiring sophisticated retry/timeout/cancellation logic, or systems where resource leaks are critical concerns. The investment in learning Effect pays dividends when you need its integrated approach to managing effectful computations, but represents over-engineering for straightforward CRUD applications or libraries focused solely on better error types. Teams must be prepared for a multi-week learning curve and larger bundle sizes.