Question: Is there an open-source chat solution that allows me to connect to any API and customize the user interface?

If you're looking for an open-source chat solution that lets you connect to any API and customize the user interface, Deep Chat could be the way to go. This framework-agnostic, customizable chat component supports media transfer, Markdown formatting, and connections to several AI services. It's easy to install with npm or a CDN, and it's highly customizable with lots of options.

Another good option is Botpress, a ChatGPT chatbot builder that uses OpenAI's Large Language Models. It has more than 100 integrations, including WhatsApp and Telegram, and has features like professional greetings, database synchronization and an API for customization. It has a free tier, but also paid options for security, scalability and other features.

If you prefer a no-code approach, Chaindesk offers a service to create your own custom AI chatbots to handle customer support and lead generation. It offers immediate answers, omnichannel conversations and integration with many data sources. The service can be deployed to a website or other tools, too, making it a good option for businesses that want to improve customer service and automate some workflow.

Last, Chat Data offers a flexible backend for your own models and a branded interface for styling. It has features like human support escalation and e-commerce store integration, too. With flexible pricing and add-ons, Chat Data offers a scalable foundation for building and deploying your own AI chatbots.