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Native Clojure implementation of jsonschema, including a validator
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malcolmsparks Add schema restrictions
There are many parts of the spec which dictate the structure of
schemas themselves.
Latest commit e69ec8e Jun 17, 2019


JSON Schema for Clojure(Script)

Almost all Clojure implementations of json schema validators wrap Java libraries. This is generally a good idea.

However, there are some reasons why a native Clojure implementation can be useful:

  • Java libraries compile jsonschema to object graphs, making them inaccessible to many of the data functions in the Clojure core library.

  • On the front-end, it can be painful to have to convert Clojure data to JavaScript objects simply for the purposes of calling a jsonschema validation such as Ajv.

  • Extensibility: JSON Schema is designed to be extended with additional vocabularies. Clojure has some nice open-for-extension mechanisms.

  • Size: Implementing JSON Schema is not that scary in a language as nice as Clojure. There’s not so much code to read, understand and possibly extend.


This library implements JSON Schema 'draft7' (draft-handrews-json-schema-validation-01).


This is a new project, of alpha status. There may be future incompatible changes ahead.

Most core features are working but there is more work yet to do:

  • Annotation gathering

  • Improved Error messages

  • The schema-path and data-path values on failures

  • Relative json-pointer

This library is tested with the official JSON-Schema-Test-Suite.

Currently, 631 of the 633 official optional and non-optional tests pass. Failing tests include support for uri-template and idn-email.


A schema is a Clojure map (or boolean) that should be augmented with metadata by calling juxt.jsonschema.schema/schema on the schema data:

(juxt.jsonschema.schema/schema {"type" "object"})


Validation can take an optional options map.

The :resolvers entry should be a collection of resolvers.

  • :juxt.jsonschema.resolve/built-in is the built-in resolver which will resolve schemas contained in the library, such as the draft7 meta-schema.

  • :juxt.jsonschema.resolve/default-resolver is a resolver which takes an argument of a map of URIs (or regexes) to values.

    A value can be a schema (which should be pre-processed with schema metadata by calling juxt.jsonschema.schema/schema).

    A value may also be a function (called with the URI or, in the case of a regex, the result of the regex match):

    {#"*)" (fn [match] {:type "object"
                                                     :path (second match)})}

Alternative implementations

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