Closed Source Models

What it is

Closed source models are proprietary AI models where only the creators have access to the weights and training details. You interact through APIs or products. GPT-4, Claude, and Gemini are closed source. You pay for access but can't download or modify the actual model.

Why it matters

Closed source models are typically more capable, regularly updated, and easier to use—no hardware required. The trade-offs are cost, privacy (data goes to the provider), and dependency on the vendor's decisions. For many use cases, these trade-offs are acceptable for access to frontier capabilities.