CoreCoder One
A.k.a CoreCoder is a free, open source code editor made specifically to edit minecraft files. Including addons, functionss, loot tables, etc. It is licensed under Apache-2.0 License
Free on Itch.io Source Code
CoreCoder:Studio
CoreCoder:Studio is a successor of CoreCoder. Rebuild from stratch for better performance, and lower RAM usages, allowing user to run minecraft more smoothly while making addons. CoreCoder:Studio also comes with extra features such as Github Integration, in-built editor for many more files, etc.
CoreCoder:Studio is available for purchase at Itch.io or by supporting at least $1 USD per month on patreon.
View Support on Patreon