With Ollama you can install and use various free AI models.

What do you mean by Grammarly costs a lot of money? It has a free tier. Which is quite generous.

If you are a student, you should be able to organize with some of your classmates or friends.

Also, maybe consider LanguageTool instead of Grammarly, at least it's not fully closed source.

You can get a pretty decent free version of ChatGPT's newest model by using the Microsoft Edge browser and going to Bing chat. You're limited to how long you can have a single discussion, but it's better than going to the limited version on ChatGPT's official website.

I’m not sure how you’ll be using these tools but Jan might be an option. There are some free AI models you can download and use right in the app locally. https://jan.ai/

The following AI tool can parse documents and use the Internet, and multiple LLM model to choose:

• https://github.com/woheller69/huggingassist // There's censorship with all of them but this is a special one.
• https://tryfastgpt.ai/ //A free account is restricted to 100 points, but you can create another account afterward, didn't tested that though yet.
• https://play.google.com/store/apps/details?id=ai.perplexity.app.android