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ComfyUI

The nodal workflow engine for serious diffusion.

Open Source 6–16 GB VRAMRuns locally
Actually FreeNo SignupOpen SourceWatermark-FreeHobbyist-FriendlyWorkflow Engine
Visit ComfyUIUpdated 2026-05-19 · Direct link

Hardware requirements

Runs locally · Mid GPU (12 GB)

6–16 GB VRAM
Min VRAM
6 GB
Rec. VRAM
16 GB
Min RAM
16 GB
Rec. RAM
32 GB
Disk
50 GB
GPU class
Mid GPU
CUDA 12.x (NVIDIA) or ROCm 6 (AMD) or MPS (Apple)Apple Silicon ✓GPU RequiredQuant: FP16, FP8, GGUF +1

SDXL needs ~8 GB VRAM. Flux dev FP8 fits in 12 GB. Hunyuan / Wan video want 24 GB+.

Screenshot placeholder · ComfyUI

What is ComfyUI?

ComfyUI is a node-based UI for Stable Diffusion / SDXL / Flux / SD3 / Hunyuan / Wan and everything in between. Every step of a pipeline — loader, sampler, conditioning, VAE, post — is a node you wire together. The de-facto platform for advanced image & video diffusion workflows.

Pros & cons

Pros

  • Most flexible diffusion pipeline anywhere
  • Massive custom-node ecosystem
  • First to support new models (Flux, SD3, Wan, Hunyuan)
  • Workflows are JSON — share/version them in git

Cons

  • Steep learning curve — graph thinking required
  • Workflows break when nodes update
  • No first-class queue / multi-user out of the box

What's actually free?

Fully free and open source. You provide the hardware (or rent a GPU pod).

✓ Actually FreeNo SignupOpen SourceWatermark-Free

Alternatives

InvokeAI

Production-leaning SD studio with canvas & batch.

Open Source 8–16 GB VRAM
Min VRAM
8 GB
GPU class
Mid GPU
Quant
FP16
Actually FreeNo SignupOpen SourceWatermark-Free

SwarmUI

Power-user front-end that wraps ComfyUI.

Open Source 8–24 GB VRAM
Min VRAM
8 GB
GPU class
High-end GPU
Quant
FP16
Actually FreeNo SignupOpen SourceWatermark-Free