Best Open-Source AI Image Generators 2026: 6 Options Compared
Best open-source AI Image Generators compared: ComfyUI, Invoke, Fooocus, Stable Diffusion web UI (AUTOMATIC1111) and 2 more, with licenses, platforms and prices from official pages checked October 24, 2026.
•4 min read•Photo Editing & AI Images
Quick comparison
| Tool | Price | Platforms | Best for | Tested |
|---|---|---|---|---|
| ComfyUI | Free (Free to run locally; Comfy Cloud is a separate paid hosted option) | Windows, macOS, Linux | Users who want maximum control | Docs only |
| Invoke | Free (Free to use locally under the repository license; hosted Invoke plans were not checked) | Windows, macOS, Linux | Editing and compositing images | Docs only |
| Fooocus | Free (Free and offline; the README gives a minimum of 4 GB of Nvidia GPU memory) | Windows, Linux, Self-hosted (Python) | Beginners who want Midjourney-style ease | Docs only |
| Stable Diffusion web UI (AUTOMATIC1111) | Free (Free to run on your own hardware; model weights carry their own licenses) | Self-hosted (Python) | Users who want extensions and tutorials | Docs only |
| SD.Next | Free (Free to run on your own hardware; model weights carry their own licenses) | Self-hosted (Python) | A maintained, extensible web UI | Docs only |
| Stable Diffusion WebUI Forge | Free (Free to run on your own hardware; model weights carry their own licenses) | Self-hosted (Python) | Lower-memory GPUs | Docs only |
Independent comparison. Paid placements are labelled separately; editorial links earn no affiliate commissions. Learn more.
Good fit if
- You want the simplest prompt-and-go tool (Fooocus is the pick)
- You want a node workflow and new model support fast (ComfyUI is the pick)
- You edit existing images a lot (Invoke is the pick)
- You want plugins and community guides (Stable Diffusion web UI (AUTOMATIC1111) is the pick)
- You want an actively updated web UI (SD.Next is the pick)
Not ideal if
- You cannot host, patch and back up a server yourself and want a vendor to run it
Open-source AI image generators are interfaces for diffusion models, and the interface and the model carry different licenses. The programs below are free and licensed under GPL, AGPL or Apache terms, but the checkpoints you download into them, such as Stable Diffusion variants, come with their own rules, some of which limit commercial use. Check the model card before you sell what you generate. Hardware is the bigger limit. Most of these tools want an Nvidia graphics card with several gigabytes of memory, and a few run on CPU or Apple silicon at a painful speed. Fooocus is the gentlest: you type a prompt and it handles the settings, with a stated minimum of 4 GB of Nvidia memory, though it is now in bug-fix-only maintenance. AUTOMATIC1111 and its descendants, Forge and SD.Next, expose every setting and a large extension ecosystem. ComfyUI uses a node graph that takes longer to learn but gives the most control and the quickest support for new models. InvokeAI focuses on a canvas for inpainting and outpainting. Pick the one that matches how much tuning you want, and install only one at first, because the model files are large and shared between them poorly.
ComfyUI
GPL-3.0 node-based interface for local image and video models, with a desktop app for Windows and macOS. Powerful but with a steep learning curve; Comfy Cloud is a separate paid service.
Price: Free (Free to run locally; Comfy Cloud is a separate paid hosted option) (ComfyUI pricing, checked 2026-10-22).
Platforms and license: Windows, macOS, Linux. GPL-3.0 (open source) (license source).
Project activity: 143.6k GitHub stars · latest release v0.43.0 (Oct 27, 2026) · last commit Oct 27, 2026
Best for: Users who want maximum control.
Invoke
Apache-2.0 tool with a canvas for inpainting and outpainting plus node workflows. Free to use locally; model licenses are separate, and hosted Invoke plans were not checked.
Price: Free (Free to use locally under the repository license; hosted Invoke plans were not checked) (Invoke pricing, checked 2026-10-22).
Platforms and license: Windows, macOS, Linux. Apache-2.0 (open source) (license source).
Project activity: 28.9k GitHub stars · latest release v6.14.2 (Sep 27, 2026) · last commit Oct 27, 2026
Best for: Editing and compositing images.
Fooocus
GPL-3.0 and built on SDXL, with a stated minimum of 4 GB of Nvidia GPU memory. It is in limited long-term support with bug fixes only, so expect no new features.
Price: Free (Free and offline; the README gives a minimum of 4 GB of Nvidia GPU memory) (Fooocus pricing, checked 2026-10-24).
Platforms and license: Windows, Linux, Self-hosted (Python). GPL-3.0 (open source) (license source).
Project activity: 53.7k GitHub stars · latest release v2.5.5 (Aug 12, 2024) · last commit Dec 1, 2025
Best for: Beginners who want Midjourney-style ease.
Stable Diffusion web UI (AUTOMATIC1111)
AGPL-3.0 web UI with the largest extension ecosystem for Stable Diffusion. The license covers the interface, not the checkpoints you load into it.
Price: Free (Free to run on your own hardware; model weights carry their own licenses) (Stable Diffusion web UI (AUTOMATIC1111) pricing, checked 2026-10-24).
Platforms and license: Self-hosted (Python). AGPL-3.0 (open source) (license source).
Project activity: 165.2k GitHub stars · latest release v1.10.1 (Feb 9, 2025) · last commit Mar 2, 2026
Best for: Users who want extensions and tutorials.
Worth knowing: Repository metadata checked 2026-10-23. The AGPL covers the web UI code, not the checkpoints you download for it.
SD.Next
Apache-2.0 fork of the Stable Diffusion web UI that is actively updated. The license covers the interface only; model weights carry their own terms.
Price: Free (Free to run on your own hardware; model weights carry their own licenses) (SD.Next pricing, checked 2026-10-24).
Platforms and license: Self-hosted (Python). Apache-2.0 (open source) (license source).
Project activity: 7.4k GitHub stars · last commit Oct 27, 2026
Best for: A maintained, extensible web UI.
Worth knowing: Repository metadata checked 2026-10-24. The Apache-2.0 license covers the interface code, not the checkpoints you load.
Stable Diffusion WebUI Forge
AGPL-3.0 build of the web UI aimed at speed and lower memory use. The last push we saw was July 2025, so check recent activity before relying on it.
Price: Free (Free to run on your own hardware; model weights carry their own licenses) (Stable Diffusion WebUI Forge pricing, checked 2026-10-24).
Platforms and license: Self-hosted (Python). AGPL-3.0 (open source) (license source).
Project activity: 13.1k GitHub stars · latest release latest (Feb 5, 2024) · No commits since Jul 31, 2025
Best for: Lower-memory GPUs.
Worth knowing: Repository metadata checked 2026-10-24: AGPL-3.0, last push July 2025, so check activity before committing to it.
Which one to pick
- You want the simplest prompt-and-go tool: Fooocus
- You want a node workflow and new model support fast: ComfyUI
- You edit existing images a lot: Invoke
- You want plugins and community guides: Stable Diffusion web UI (AUTOMATIC1111)
- You want an actively updated web UI: SD.Next
Limits of this review
Docs-only for ComfyUI, Invoke, Fooocus, Stable Diffusion web UI (AUTOMATIC1111), SD.Next, Stable Diffusion WebUI Forge: we did not install or run them, so feature claims come from vendor pages. Vendor prices and free limits change; confirm on the linked pricing page before you commit.
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Kevin Fan
Kevin Fan is a SaaS founder. He runs Free Instead Of, which tracks free and open-source alternatives to paid software and checks each price and free-plan limit against the vendor's own pages.
Methodology
Based on official pricing, license and product pages checked between 2026-10-22 and 2026-10-24: ComfyUI, Invoke, Fooocus, Stable Diffusion web UI (AUTOMATIC1111), SD.Next, Stable Diffusion WebUI Forge. Prices, free limits and licenses are the figures shown on those pages on those dates. No tool on this page was installed or run. No accounts were created.