FLUX.1 [dev] API
FLUX.1 [dev] is a 12 billion parameter text-to-image model by Black Forest Labs built on a rectified flow transformer architecture. Known for strong prompt adherence, fine detail, and photorealism — it's one of the best open-weight Flux AI image generators available. Run it on Runflow with a single API call and pair with Sentinel to control quality on every output.
Flux AI model family by Black Forest Labs
Different Flux variants for different needs — all accessible through the same Runflow image generation API.
FLUX.1 [dev]
This modelOpen-weight, 12B params, highest detail among open models
FLUX.2 Klein
SpeedSub-second generation with state-of-the-art quality
FLUX.1 Kontext
EditingIn-context image generation and editing
FLUX.1 [dev] image generation examples
Real images generated with the FLUX.1 [dev] text-to-image model via the Runflow API — one API call per image, no post-processing.
![AI-generated professional headshot of a woman with neutral grey background and soft studio lighting — created with FLUX.1 [dev] via Runflow API](/_next/image?url=%2Fimages%2Fmodels%2Fblack-forest-labs%2Fflux-1-dev%2Fportrait.jpg&w=3840&q=75&dpl=dpl_4n6iJySrEqeLgoAARTpFs6nYAju4)
"Professional headshot of a woman, neutral grey background, soft studio lighting, sharp focus, corporate portrait"
![AI-generated fashion editorial photo of a model wearing an oversized black blazer in a minimalist white studio — created with FLUX.1 [dev] via Runflow API](/_next/image?url=%2Fimages%2Fmodels%2Fblack-forest-labs%2Fflux-1-dev%2Ffashion.jpg&w=3840&q=75&dpl=dpl_4n6iJySrEqeLgoAARTpFs6nYAju4)
"High-end fashion editorial, model wearing oversized blazer, minimalist white studio, dramatic side lighting"
![AI-generated product photography of white sneakers on a reflective surface with clean commercial lighting — created with FLUX.1 [dev] via Runflow API](/_next/image?url=%2Fimages%2Fmodels%2Fblack-forest-labs%2Fflux-1-dev%2Fproduct.jpg&w=3840&q=75&dpl=dpl_4n6iJySrEqeLgoAARTpFs6nYAju4)
"Product photography, white sneakers on reflective surface, clean background, commercial lighting"
![AI-generated surreal landscape with floating islands at golden hour with cinematic composition — created with FLUX.1 [dev] via Runflow API](/_next/image?url=%2Fimages%2Fmodels%2Fblack-forest-labs%2Fflux-1-dev%2Fcreative.jpg&w=3840&q=75&dpl=dpl_4n6iJySrEqeLgoAARTpFs6nYAju4)
"Surreal landscape with floating islands, golden hour light, cinematic composition, 8k detail"
Benchmarked for your use case
Coming soonEvery model on Runflow is scored per vertical — not generic leaderboard numbers. Scores come from domain-expert evaluation on real production prompts. Benchmark results for FLUX.1 [dev] are currently in progress.
| Use Case | Quality Score | Status |
|---|---|---|
| Portraits | — | Benchmarking |
| Fashion | — | Benchmarking |
| Product | — | Benchmarking |
| Creative | — | Benchmarking |
API Parameters
Full parameter reference for the flux-1-dev model endpoint.
| Parameter | Type | Description |
|---|---|---|
| prompt | string | Text description of the image to generate. |
| width | integer | Image width in pixels. Default: 1024. |
| height | integer | Image height in pixels. Default: 1024. |
| num_inference_steps | integer | Number of denoising steps. Range: 10–50. Default: 50. Higher = better quality, slower. |
| guidance_scale | float | How closely the model follows the prompt. Range: 1–20. Default: 3.5. |
| num_images | integer | Number of images to generate. Range: 1–4. Default: 1. |
| seed | integer | Random seed for reproducible results. Same seed + prompt = identical output. |
| output_format | string | Output image format. Options: "jpeg", "png". Default: "jpeg". |
Technical Specifications
Why run FLUX.1 [dev] on the Runflow API
Flux AI models are available on many platforms. Here's what makes the Runflow image generation API different.
Benchmarked per niche
We don't give you a generic quality number. Every model is scored for portraits, fashion, product, and creative — so you pick the right model for your use case, not the hyped one.
Fixed per-image pricing
No GPU-second billing. No cold-start surcharges. Simple fixed pricing per image. Predictable costs at any scale. Pricing details coming soon.
Sentinel: control every output
AI generation isn't deterministic — some outputs miss the mark. Sentinel evaluates every image before delivery, scoring against your criteria. Bad outputs get caught and retried automatically. Your customers only see quality.
Learn moreBuilt for reliability
Multi-region GPU infrastructure with automatic failover. Your pipeline doesn't go down because one datacenter has a bad day.
One API for every model
Switch from FLUX.1 to Seedream to SDXL by changing one parameter. No vendor lock-in, no different SDKs, no rewriting integrations.
Production-tested
Built by a team that ran 100,000+ inference jobs in production before launching the platform. Not a wrapper — real infrastructure.
Learn moreExplore other models
Same API, different strengths. Switch models with one parameter change.
FLUX.1 Kontext
In-context image generation and editing
EditingFLUX.2 Klein
Sub-second generation, state-of-the-art quality
SpeedSeedream 4.5
Strong performer for product photography
ProductReve
High-quality creative image generation
CreativeQwen Image Max
Versatile multimodal image model
MultimodalKling 3.0
Video generation from text and image
VideoFrequently asked questions
Resources
Start generating images with FLUX.1 [dev]
Get Flux API access in minutes. No GPU setup, no infrastructure to manage. Pair with Sentinel to control the quality of every AI-generated image you ship.