JSONia

JSONia is a data description and interchange format conceived as an extension of JSON. It aims to provide a self-describing, schema-driven encoding for data interchange, combining the ubiquity of JSON with richer type information and validation semantics. Proposals for JSONia emerged in the mid-2020s within open-source and academic discussions as a way to reduce the friction between data producers and consumers by embedding schema-like constraints directly in the payload.

JSONia documents are JSON-like in syntax with optional annotations. Beyond standard JSON types, JSONia introduces primitive types such as date, time, and decimal, and supports type annotations at the value level using a companion metadata object under a reserved key, for example $type. It also allows inline schema definitions via a $schema property, enabling self-describing messages that can be validated without a separate schema repository.

Validation in JSONia can be performed locally or by a central validator. A JSONia validator checks value conformance, constraints, required fields, and cross-field relationships, using a JSON-like Schema Language that blends elements of JSON Schema with typing concepts from statically typed languages. Because JSONia is designed to be backward-compatible, existing JSON documents may be carried inside JSONia envelopes without breaking standard parsers.

Tooling and ecosystem support remain the main hurdle. Critics note potential complexity, configuration proliferation, and performance considerations for large-scale validation. Proponents argue that the approach improves data quality and interoperability by making schemas portable and machine-checkable within the payload.

See also: JSON, JSON Schema.