CheckcraftValidate JSON against a JSON Schema online
Checkcraft is a desktop app for checking APIs and logs without code, with a free edition. Download, no sign-up →
A schema describes what a response should look like. Here you see where a particular response departs from it, with the field path and a clear reason.
What is checked
type, enum, const, required, properties, additionalProperties, patternProperties, propertyNames, items and prefixItems, minItems and maxItems, uniqueItems, contains, minLength and maxLength, pattern, minimum and maximum including exclusive ones, multipleOf, allOf, anyOf, oneOf, not, if, then, else, dependentRequired and $ref references within the schema via #/$defs or #/definitions. The date, date-time, email, uuid, uri and ipv4 formats are checked; others are listed as not checked.
What is not supported
References to external files and URLs, $anchor, $dynamicRef, unevaluatedProperties and unevaluatedItems. If the schema uses them, a “Not checked” line appears under the result so that a green result does not mislead you. For a schema from OpenAPI 3.0, note that nullable is ignored here: allow null through type.
A schema checks shape, not meaning
A response can fully match the schema and still be wrong: the order total is a number, just not the right one. That is why value and calculation checks are added on top. In Checkcraft these are field and calculation rules that run on every pass. A script in your browser does the work; the page sends nothing to a server.
Repeat this on your own API
Checkcraft is a desktop app that saves API response checks without code and shows what did not match. Start with a sample, then use your own sanitized data. Free runs on Windows and Linux with no time limit.
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References
Start with the linked example and compare its result with your own test requirement.