AJV - the JSON Schema validator

• Ajv is the fastest JSON Schema validator for node.js and browser.
• Ajv compiles schemas into functions - ajv.compile(<your schema>)
• ajv.validate(<your json data>) returns the errors.

So far I feel comfortable with this site to practice JSON validations: 

https://json-schema-validator.herokuapp.com/

Read more:
https://www.npmjs.com/package/ajv

http://json-schema.org/latest/json-schema-validation.html

http://www.jsonschemavalidator.net/

https://json-schema-validator.herokuapp.com/

http://www.jsonschemavalidator.net/

http://regexr.com/

https://davidwalsh.name/json-validation
https://spacetelescope.github.io/understanding-json-schema/reference/combining.html
http://json-schema.org/example2.html