Question: Do you know of a language learning tool that allows me to customize my learning experience with personalized AI models and prompts?

If you want a language learning tool that lets you customize with your own AI models and prompts, Praktika is a strong contender. This service offers an AI-powered, automated 1-1 tutorship experience with generative AI Avatar Tutors designed to improve English language skills. It personalizes the experience based on your context, language proficiency and personal background. It offers real-time conversations, immediate feedback and adaptive progress tracking.

Another interesting option is Speak, which uses AI technology like GPT-4 for conversational language learning with no human teacher. The app offers free-form conversations and feedback on vocabulary and grammar, with integration with OpenAI's automatic speech recognition API for better results. It also comes with a ChatGPT plugin for tutoring that takes place within the chat interface, making it a good choice if you want to practice your language skills in a chat setting.

SpeakAI is another full-featured service that offers customized learning paths and interactive exercises in several languages, including English, Chinese, Japanese and others. It offers real-time grammar correction and interactive dialogue modes for conversational practice in simulated situations. SpeakAI is good for practicing pronunciation and fluency in a more dynamic setting.

If you prefer a more interactive approach, PrettyPolly lets you practice speaking with AI characters you can customize. It offers personalized feedback and fluency scores, pronunciation assessments and spaced repetition flashcards. PrettyPolly supports 36 languages and focuses on practical speaking skills with no fear of embarrassment, so it's good for self-improvement.