json-schematics-v2

json-schematics-v2 is a zero-dependency Go library for declarative JSON validation. It addresses the limitations of traditional validation approaches when handling messy or unpredictable JSON data from third-party sources and dynamic forms.

The library flattens any nested JSON document into dotted keys. It then matches those keys using wildcards or regex before routing each value through a pipeline of validators and operators. Five distinct stages handle flattening, matching, validation, operation, and output. Schemas are expressed as data rather than compiled code, allowing rules to be loaded, shipped, or localized without redeployment. It returns typed errors and never panics on unexpected values.

A playground and documentation illustrate the process with an example that validates fields such as name with a minimum length, age within a numeric range, and email format. The approach contrasts with struct tags that hard-code shapes at compile time and with reflection-based validators that can panic on malformed input. Rules remain separate from application code, supporting scenarios where validation logic must change independently of deployment cycles.

It is delivered as a Go module installed via the command go get github.com/ashbeelghouri/json-schematics-v2@latest and targets Go 1.24. The project provides reference documentation, examples, and tests hosted on its site along with a GitHub repository.