Funkjson

Funkjson is a lightweight data-interchange format and accompanying toolchain that extends JSON with constructs for functional-style transformation, streaming parsing, and compact annotations. It is designed to make common data manipulation tasks—such as mapping, filtering and folding—expressible as concise, composable operations embedded alongside declarative data structures.

The format retains JSON compatibility for basic objects and arrays but introduces a small set of syntactic conventions and metadata markers to indicate transform expressions, lazy evaluation hints and optional type annotations. Implementations typically provide a runtime that can evaluate embedded transform expressions either at parse time or via a stream-oriented API, enabling pipelines that combine parsing, transformation and serialization with low memory overhead.

Funkjson is implemented in several languages by independent projects and is distributed under permissive open-source licenses in most cases. It is most often used in data engineering, event processing and configuration contexts where compact expressiveness and pipeline efficiency are priorities. Advocates cite improved readability for transformation-heavy payloads and simpler integration with functional programming idioms.

Criticisms include increased complexity over plain JSON, potential security risks when evaluating embedded expressions, and limited standardization across implementations. As a result, adoption is primarily niche and often coupled with project-specific tooling rather than broad ecosystem support.