iPlug2 - is a free, liberally licensed, open source audio plug-in framework.
iPlug2 discussions happen at the iPlug2 forum and on the iPlug2 discord server - see you there!
If you want to start a new iPlug2 project, the recommended way is with iPlug2OOS, which is a template repository set up with github actions ready to build your project automatically in the cloud.
iPlug2 API documentation is published here and be sure to check out the iPlug2 Wiki
Please consider contributing your time to help fix issues or add features and/or supporting the project via github sponsors.