While the coding assistants are pretty much universally free, you still need to connect them to a model. The model tokens generally cost something once you've gone past a certain quota.

I'm not sure if this is still true, but if you have a Google account, Gemini Code Assist had a quite generous "free tier" that I used for a while and found it do be pretty decent.

It is fun to use.

You log in with your Goggle account.

Opencoder is bring your own model.

You get what you pay for so good luck.