OdinRunes

Odin Runes, a java-based GPT client, facilitates interaction with your preferred GPT model right through your favorite text editor. There is more: It also facilitates prompt-engineering by extracting context from diverse sources using technologies such as OCR, enhancing overall productivity and saving costs. Maintained by leonid20000 on GitHub, where it has earned 91 stars from the community.

It's actively developed around gpt-client, ai-assistant, custom-gpt, and is a solid reference for anyone building with these tools.