Multi-Platform AI Chat App Development

I'm looking for an experienced AI app developer to create an AI chat application similar to ChatGPT. The app should be available on iOS, Android, and Web platforms.

Key features include:
- Voice interaction
- Multi-language support
- User authentication

Ideal skills and experience:
- Strong background in AI and app development
- Experience with voice interaction technologies
- Expertise in multi-language integration
- Solid knowledge of user authentication protocols

Please share your previous work in AI apps and relevant platforms.