easyjson is a code generator that produces fast JSON serializers and deserializers for Go structs.
The tool addresses the performance overhead of Go's standard encoding/json package, which relies on reflection. easyjson generates specialized marshaling and unmarshaling functions at compile time by analyzing struct definitions and producing optimized Go code. This approach eliminates runtime reflection entirely, delivering significant speed improvements. The generated code remains readable and maintainable, allowing developers to understand and modify it if needed.
Developers should choose easyjson when JSON serialization performance is critical in their application. It suits projects handling high volumes of JSON data or operating under strict latency constraints. The tool is particularly valuable when compared to the standard library's encoding/json package, which it outperforms by a factor of 4-5x, and other third-party JSON packages, which it typically exceeds by 2-3x. Beyond raw speed, easyjson offers customization options unavailable in the standard library, including automatic snake_case field name generation, default omitempty behavior, string interning for memory efficiency, and nocopy mode for short-lived objects that reference the original JSON buffer.
The project maintains active continuous integration workflows. Development follows a structured approach to code generation, requiring a full Go build environment and GOPATH configuration since the tool invokes go run on temporary files during generation. The codebase demonstrates consistent attention to both performance optimization and code clarity as design principles.
