Most active

• gitter-ada - Ada Dev’s channel on Gitter

• comp-lang-ada - Q&A Threads with Ada Experts on Usenet
• subreddit-ada - Ada general questions and announcements on Reddit.
• subreddit-spark - Spark on Reddit.

Others

• stack-overflow-ada-tag - Ada at Stack Overflow.
• telegram-ada - Ada group at Telegram.
• #ada on Libera.Chat - Ada channel at IRC.
• matrix-ada - Ada room at Matrix.