FEJSONlike

FEJSONlike is a data interchange format defined as an extension of JSON, designed to be more human-friendly for front-end development and configuration use cases. It emerged from an open community in the early 2020s, with the first draft published around 2022, and has since seen adoption in web applications, tooling, and project configurations.

The core data model matches JSON, including objects, arrays, strings, numbers, booleans, and null. FEJSONlike adds optional syntax features intended to improve readability and typing without breaking basic parsers: inline and block comments, and trailing commas. Whitespace and line breaks remain insignificant, maintaining JSON-like determinism for basic data.

Typing extensions: FEJSONlike introduces a lightweight type annotation mechanism to represent common literals such as dates, timestamps, binary data, and UUIDs. Type information is provided via a small wrapper using a __type field and a value field, and can be omitted for plain JSON values. These features are optional and designed to be ignored by strict JSON parsers when stripped.

Practical use and tooling: Libraries exist for several languages, enabling FEJSONlike parsing and serialization, typically configurable to enable or disable nonstandard features. The format is used for configuration files, API payloads, and data models where readability and typing are valued. It remains a community-driven spec with evolving proposals and partial implementations.

Limitations and interoperability: Because FEJSONlike adds nonstandard features, full interop with strict JSON tooling is not guaranteed; validators and APIs may need to be configured to accept or ignore extensions. Users evaluating FEJSONlike should consider ecosystem maturity and tool support.