Here are some specifications for the use cases and properties that would be nice to have in this type of tool:
Use cases:

1. create a complete codemeta.json file from scratch
2. aggregate existing information and add complementary information to a codemeta.json file

Properties:

• helpers while completing the form, for example a reference list of spdx licenses
• a validation mechanism after submission
• the possibility to use all the codeMeta terms and schema.org terms
• accessible from multiple platforms (web browsers or OS)
• (extra) the possibility to correct the output after validation as part of the creation process

The link to the preliminary document with a couple of tools that still need documenting and testing on the survey:
https://docs.google.com/spreadsheets/d/1AGdEeYisIMDBtP0B-PT8tY2QpJX6ukMu0E4M_2MgR0k/edit?usp=sharing

This tool was initially prepared for the FORCE19 Hackathon