What's free
$2 in signup credits across first-party image models (FLUX.1/FLUX.2, Stable Diffusion 3, SDXL) on the Sonic Inference Engine — hundreds to thousands of generations
Rate limits
Not publicly specified; per-account concurrency applies
The catch
The $2 requires signup with a business email (personal/free-mail domains may be rejected); one-time, non-renewing. No watermark, no card, commercial use allowed. The OpenAI-compatible endpoint is chat-only, not for images.