These are the best #flutter communities to collaborate with other developers and seek/give help.

A Thread

Flutter Slack Channel: there are dozens of channels covering a variety of topics. Thousands of active developers on it as well, giving advice, debug help, showing off work, sharing articles, and more.

https://app.slack.com/client/TGT6YF2J1

Flutter Dev Reddit: More discussion and sharing of articles/videos than giving/receiving of help, but a great place none-the-less to meet and discuss with other flutter devs. Debug help found occasionally too. https://www.reddit.com/r/FlutterDev/ 

Flutter Discord Channel: Similar to slack in terms of active users, this Discord channel is great for connecting with other devs, getting help with questions and more. There are also many other discord channels for individual Flutter Youtube communities. https://discord.gg/N7Yshp4 

Some other Discord channels run by Flutter YouTubers include those of @tadaspetra, myself: @BleylDev, @RobertBrunhage, and more. If you have a favorite YT channel, be sure to see if they have a discord channel as well that you can join.

Flutter Dev Twitter: There are thousands of active Flutter developers here on Twitter constantly sharing ideas, code, tips, work, articles, etc. Be sure to check out this compiled list of developers here on Twitter.

https://twitter.com/i/lists/1273736213665636359?s=20

I'm sure I've left out some other communities too, so if you know of one that thousands of Flutter developers use, be sure to comment it below for others to find