Question: I need a tool that helps me improve my language skills, especially with grammar, vocabulary, and cultural differences.

Speak is a good option, using AI technology like GPT-4 for a conversational language learning experience. It lets you have free-form conversations and get feedback on vocabulary and grammar, and it uses OpenAI's automatic speech recognition API for better results. Speak also has a ChatGPT plugin for language tutoring within OpenAI's chat interface and plans to add more languages besides English.

Another good option is SpeakAI, which offers a more fleshed out AI language learning experience with a personalized learning path and interactive exercises. SpeakAI supports Chinese, English, Japanese, Korean, French, German, Italian and Spanish, and offers real-time grammar correction and scenario-based courses for more practical language learning.

For a more interactive and globally focused learning experience, HiNative supports more than 110 languages and lets you ask questions and get answers from both AI and native speakers. It spotlights authentic expressions, pronunciation feedback and human input, so it's good for honing language skills in grammar, vocabulary and cultural differences. The app is available as a free download, though some features are available without paying.

Last, Talkpal is a GPT-powered AI language learning tool with interactive conversations, real-time feedback and active listening exercises that change as you respond. It supports many languages and has features like roleplays and debates to improve speaking, listening, writing and pronunciation. The tool offers a free plan with basic chat abilities and several premium plans, so it's within reach of many budgets.