Last updated: April 5, 2026 · Pricing & Deployment · by Daniel Ashford
What is Open Source / Open Weights?
LLMs whose model weights are publicly available for download and self-hosting.
Definition
Open weights LLMs are models whose trained parameters are publicly released, allowing anyone to download, run, fine-tune, and deploy them without per-token API fees.
How It Works
Major open-weight families include Llama (Meta), Qwen (Alibaba), Mistral, DeepSeek, and Gemma (Google). Licensing varies: MIT and Apache 2.0 allow unrestricted commercial use. Open models lag frontier closed models by 6-12 months but are catching up rapidly.
Example
Llama 4 405B can be downloaded and run on your own GPUs. A company processing 500M tokens/month saves approximately $15-50K/month vs commercial API pricing.
Related Terms
See How Models Compare
Understanding open source / open weights is important when choosing the right AI model. See how 12 models compare on our leaderboard.