The QCSchema project is a JSON schema that defines common inputs & outputs for quantum chemistry computations. By utilizing the schema, users have the ability to use a wide range of quantum chemistry packages without needing to tediously prepare inputs for each one. The schema also defines common structures used in chemistry, such as molecules.
For developers, implementing QCSchema into your own quantum chemistry package ensures that your software is usable by a large number of users, including by users of the QCArchive ecosystem.
While the QCSchema project defines a JSON schema, if you are using Python, check out the QCElemental project, which makes the schema even easier to use in Python, and includes many nice features, such as powerful functionality for manipulating molecules.
For more information about QCSchema and QCElemental, checkout the GitHub link below: