Using JustImageViewer’s HTTP API with ComfyUI

ComfyUI has a built-in way to pick an image for LoadImage, but it is slow. There are custom nodes that improve this, but I tried a different approach.

The idea is simple: build a small image viewer, JustImageViewer, and add an HTTP API for external integration. Because the viewer is built with Rust and imgui-rs, it has the advantage of letting you preview and select images quickly.

Integrating ComfyUI with LoadImageFromURL

JustImageViewer setup and verification

1. Add http_port to JustImageViewer’s settings.toml to enable the web server feature. Here I will use port 8001. The paths are:

   • macOS / Linux: ~/.justImageViewer/settings.toml
   • Windows: %USERPROFILE%/.justImageViewer/settings.toml

   settings.toml example:

   http_port = 8001

2. Run the viewer, select any image, and then open http://localhost:8001/select in your web browser.

ComfyUI custom node setup

You can use the LoadImageFromURL node from https://github.com/jerrywap/ComfyUI_LoadImageFromHttpURL to load an image from a URL. However, due to caching issues, the image served by the web server may not refresh even after it changes.

To work around that, I added a force cache invalidation option with a small code change. The change is too small for a pull request, so I uploaded it as a gist. With this applied, ComfyUI looks like this:

As shown above, enter http://localhost:8001/select into LoadImageFromURL, invalidate the cache, and then set the address on that node. You can connect Preview Image to confirm that the image is applied correctly. After that, build your ComfyUI workflow and run the queue.