Shuttle 3 Diffusion
An Apache-2.0 FLUX.1 Schnell derivative that hits FLUX Dev-class quality in 4 steps.
About
Shuttle 3 Diffusion, from ShuttleAI, is a fine-tune of FLUX.1 Schnell that the authors describe as partially de-distilled: it produces images the team compares to FLUX.1 Dev or Pro in just 4 steps, and when run beyond 10 steps it enters a 'refiner mode' that sharpens detail without changing composition. The stated goal was to fix the flat details and washed-out colors of the Schnell series through a special training method. It is a small, practical model for fast local generation, with safetensors available for ComfyUI and a diffusers workflow.
The notable part is the license: ShuttleAI released it under Apache 2.0, which makes it one of the few FLUX-lineage models with a fully permissive license, FLUX.1-dev itself is non-commercial. The quality-vs-Schnell/Dev comparisons come from the ShuttleAI model card and have no independent benchmark behind them, and ShuttleAI is a small team, so maintenance depth is thinner than the big labs. A follow-up, Shuttle 3.1 Aesthetic, builds on the same base. For fast permissively-licensed generation in the FLUX ecosystem, it is a legitimate niche pick.
Specs
Context window
Pricing
Free quota
API access
Weights
Released
Benchmarks
No published benchmark scores; author claim of FLUX Dev-class quality in 4 steps (HF model card)
Provider-reported unless a source says otherwise. Benchmarks are marketing-adjacent by nature — treat them as directional.
Use cases
Trust score — 6/10
Scored 6/10 (metrics tier, metrics-v1). Evidence: shuttleai/shuttle-3-diffusion HF model card (Apache 2.0, FLUX.1 Schnell base, 4-step claim, de-distillation description); shuttle-3.1-aesthetic follow-up on the same base. Strengths: rare permissive license on FLUX-lineage weights, practical 4-step speed, ComfyUI-ready. Docked for: (1) all quality comparisons are author claims with no independent benchmarks; (2) small-team project with thin maintenance history. License: Apache-2.0.
How the trust score is built
Full methodology →- Adoption · stars/downloads, log-scaled vs peers
- 4.0/10
- Maintenance · recency, releases, issue load
- 6.0/10
- Openness · license + docs
- 9.0/10
- Manual review · sanity read + red-flag check
- 5.0/10
- · ShuttleAI; FLUX.1 Schnell derivative, partially de-distilled
- · 4-step quality claim vs FLUX Dev is author-reported with no independent benchmarks
- · Follow-up Shuttle 3.1 Aesthetic exists on the same base