Scumble

Scumble is a free, open-source desktop editor built specifically for AI inpainting. Rather than assembling a mask in one tool, running a generation workflow in another and then pulling the result back into an image editor, Scumble keeps the whole loop in a single application: you select part of a picture, say what belongs there, and the result lands as its own colour-matched layer. The original image is never touched, so the edit stays non-destructive. Scumble is aimed at people who inpaint regularly — swapping an object out, removing something unwanted, or adding something new to an existing picture — and who prefer to run the generation step themselves, either through their own ComfyUI installation or through their own provider API keys. It is an editor, not a service. The product began as a weekend project, and the maker's own reason for building it is the problem it solves. Doing a lot of inpainting meant repeating the same routine over and over: build a mask here, run a workflow there, pull everything back into an image editor, fix the edges, and repeat. Each hop between tools costs time and breaks concentration, and the final edge-fixing step is the part that decides whether an edit looks believable. Scumble was built to remove those hops by putting selection, generation and layer-based compositing in one place, so the edit you describe is the edit you get, already sitting on its own layer next to the original picture. Scumble gives you three ways to define what should change: you can select by painting a mask, by pointing at an object, or by typing what it is. Whichever route you take, every result comes back as its own layer that is colour-matched to its surroundings. That colour matching is deliberate: it means a new object, a removed sign or a replaced detail blends into the existing image instead of sitting on top of it with a visible seam. Because the result is a layer, the original stays untouched underneath and you can adjust or discard the edit without redoing the whole image. Community reaction to this approach noted that the layer-based style makes AI edits feel more like normal photo editing rather than a full regeneration of the picture. Scumble does not ship its own image model. Instead it runs on your own ComfyUI — local, remote or Comfy Cloud — or on your own API keys for services including FLUX 3, FLUX.2, GPT Image, Nano Banana, Seedream, Qwen and Ideogram, with the promise of more. That means the choice of model and the cost of generation stay with you: you pay the providers directly and Scumble takes no cut. The project is honest about its maturity on this front — it is at version 0.1.x and moving fast, and not every API provider has been tested live yet, so support for a given provider may still be rough. The API path is built with privacy in mind. Through an API, only the area around your selection leaves your machine, and the answer comes back at full resolution. Your original image is not uploaded wholesale, and what comes back is not a downscaled preview that you then have to upscale yourself. Scumble also keeps no account, sends no telemetry, and stores your API keys in the system's credential store rather than inside the app. Combined with the fact that you supply your own keys and pay providers directly, the result is an editing tool that does not sit in the middle of your data or your billing. Two prompt-level features give you more control over what the model produces. With boxes in the prompt you can draw where things go and describe each box — for example placing an object in a specific part of the frame and describing it there — a capability listed as working with FLUX 3 Image and Ideogram 4. Reference images can also be named inside a prompt, so a request such as "put their cup from @img1 on the sill" pulls a specific existing image into the edit. Together these let you direct an edit spatially and keep particular objects consistent between generations instead of describing everything from scratch in words. Scumble also exposes an MCP server with 105 tools, which means Claude Code or any other MCP client can drive the editor directly. For people who work with AI agents, that turns Scumble into something that can be operated programmatically: an assistant can select an area, request an inpaint and receive the result as a layer without a human dragging a mask each time. It is the same inpainting engine, exposed to the tooling that agents already speak, rather than a separate product bolted on the side. For finishing work, Scumble includes 46 film looks that apply as layers, a set of retouch tools, and export to PSD, ORA and TIFF. It handles pictures of 15,000 pixels and more. The export formats matter because they let an AI edit be finished elsewhere: as one commenter put it, if an AI edit is almost right it is useful to be able to complete it in another editor instead of generating again. Film looks as layers and retouch tools mean the generated result can be graded and cleaned up inside Scumble, keeping the last step of the workflow in the same place as the first. Scumble is free and open source under GPL-3.0. Windows comes first: it is available in the Microsoft Store, signed by Microsoft, and there is also a GitHub installer and a portable zip. Linux builds come out of CI, though the maker notes he has not run them himself yet, and a Mac version is planned. The project is at version 0.1.x and changing quickly, so features and provider support are still moving. Tutorials are published under the title "two sceptics, one editor" at denrakeiw.com/scumble/videos. One workflow question that comes up is how Scumble copes with larger selections or edits where the surrounding lighting and shadows need to change along with the new object. The maker's answer is candid: the AI only sees the area being edited and does not really understand what the surrounding area looks like. The new FLUX 3 model can edit areas up to 4K, which already makes the selection pretty large, and the suggested workflow is to first inpaint a larger area with FLUX 3 and then refine the details. That ordering — broad pass first, detail pass second — is a practical way to work within how inpainting models actually see an image. In short, Scumble takes the repetitive, multi-tool inpainting routine and collapses it into one free desktop editor: select by painting, pointing or typing, describe what belongs there, and receive a colour-matched layer while your original stays untouched. It runs on your own ComfyUI or your own API keys, keeps only the area around your selection away from your machine when using an API, stores keys in the system credential store and charges nothing on top of what providers charge you. With an MCP server, box prompts, named reference images, film looks and PSD/ORA/TIFF export, it is an open-source option for people who want control of the model and the data.