Image Compare (ImgSlider)

You've done the grind: fixed seed, changed one parameter, and now you want to show someone why your new settings are better. In ComfyUI that's when the ritual starts - screenshot the canvas, crop out the node spaghetti, and post a janky two-image collage where nobody can actually see the difference. Image Compare (ImgSlider) is a one-node fix for that: it turns two images into an interactive before/after slider and hands you a shareable URL you can paste into Reddit, Discord, or a client email. The author built it out of exactly this frustration, and it's the sort of small, pointed tool that quietly becomes a habit.

What it actually does

The mechanism is dead simple, and that's the appeal. You feed in two images, toggle Publish to YES, run the workflow, and the node POSTs both images to the imgslider.com API, then returns a https://imgslider.com/<uuid> link right inside the node - no console digging, no account, no API key. It also renders an inline preview in the node itself, so you get the local comparison and the published link in one pass.

Two things worth knowing under the hood. First, the node resizes image_b to match image_a when the dimensions differ (bilinear interpolation) - so the image wired into image_a (the "before", left side) sets the size. Second, it encodes both images as WebP at quality 85 for upload, which keeps the payload small at a negligible quality cost.

The inputs that matter

The node is an output node with no outputs, so there's nothing to wire downstream - it's a terminal point in your graph. Of its five inputs, three matter:

• image_a and image_b (IMAGE, required) - your before and after. Nothing runs without both.
• publish (BOOLEAN, default NO) - the whole point. Flip it to YES and run; a URL bar appears in the node. Leave it NO and you get a local preview only, which is genuinely useful on its own.

title is optional flair (defaults to "ComfyUI Slider" if empty), and api_key is optional. Skip the key and you're anonymous: free, 20 sliders a day, and links expire after 30 days. Add a token from the imgslider.com dashboard and sliders become permanent and editable, at 200/month. The rate limit error, if you hit it, is loud and clear: Rate limit exceeded. Anonymous users can create 20 sliders per day.

Installing it

Grab it via ComfyUI Manager (search "ImgSlider" or "Image Compare"), or manually:

cd ComfyUI/custom_nodes
git clone https://github.com/imgslider/ComfyUI-ImgSlider.git
pip install -r ComfyUI-ImgSlider/requirements.txt

Then restart ComfyUI. The dependency load is about as light as custom nodes get: just requests and Pillow. No model downloads, no heavy ML packages, nothing that can fight your existing environment.

Gotchas worth knowing

The big one is the 30-day expiry on anonymous links. A link you share this week is a broken link next month. If a comparison needs to live - client work, portfolio, a long-lived Discord thread - set up the free account and use an API key, or expect to re-publish.

The other thing nobody mentions until it bites: when publish is YES, your images leave your machine. The service stores them on Cloudflare R2 in western Europe. That's fine for sharing gens of a cat; it's a real consideration if you're comparing something private or under NDA. Leave publish on NO and nothing is uploaded - the node is fully local.

And if the run quietly does nothing visible, check that toggle first. publish defaults to NO, so a first-time user who forgets it gets a local preview and no link, which can look like a bug when it's just a setting.

One honest note: this is a small, indie-maintained pack from a single developer, not a ComfyUI heavyweight. It's built on one API endpoint, so it lives or dies with imgslider.com staying up. For a free utility that saves you five minutes of cropping every day, that's a trade most people happily make - but it's a trade, not a secret.