AI Playground, developed by Vercel Labs, is a web-based tool for experimenting with, fine-tuning, and comparing different AI language models. The tool offers access to leading language models, including OpenAI's GPT-3 and HuggingFace's Flan-t5-xxl, allowing users to input text and observe the model's response. Users can also compare different models and adjust model parameters to fine-tune performance. AI Playground requires a Vercel account to access its services and is ideal for data scientists, developers, and machine learning enthusiasts seeking to experiment with various language models.