See on this page: https://codemirror.net/demo/lint.htmlhtml
which uses amongst other serveral source also this: https://codemirror.net/addon/lint/json-lint.jsgit
and when using the source-view you will find this:github
// Depends on jsonlint.js from https://github.com/zaach/jsonlint
so this would be the answer: https://github.com/zaach/jsonlintjson
A JSON parser and validator with a CLI.this