I find information that JSON license is not campatible with GPL. I need to use OpenJDK for development on Java, and use json format for web-development. OpenJDK have components for working with JSON and it was licensed under GPLv2 with linking exception.

So can I use json format on my projects, that will be distributed under GPL? Why JSON license is uncompatible with GPL, but json format using in GPL licensed project like OpenJDK?

Or I mistake and it about only original implementation of JSON and not about other implementation of encoders and decoders?

1 Answer 1


Crockford's JSON license is used in some of his JSON-related software. This license does not affect other JSON implementations.

Copyright protects expression, not ideas. A standards document or a description of a data format involves copyright protection for that document/description, but not for the ideas described therein. Unless there are patents involved (which can protect ideas that are inventions), anyone can implement the specification, in this case the file format. Even if the file format itself had a license, many jurisdictions have copyright exceptions for interoperability purposes.

In any case, the normative description of JSON is not Crockford's website, but the ECMA-404 standard. The standards document is published under a license that explicitly allows implementing the standard.

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