Debug Any

Half of debugging a ComfyUI workflow is just looking at the data. What does this node actually output? Is this a string or a dict? Is that bundle key empty? Debug Any is the answer: connect any wire to its single input and it shows the value as a text preview right below the node. No console spelunking, no "print somewhere and hope."

What it does

One optional input, input, of any type - and no outputs. It's an output/terminal node, so you hang it off whatever you're curious about. It renders the value inline:

• Primitives show as-is - a string shows the string, an int a number, a boolean true/false.
• Complex types get serialized to JSON where possible, indented for readability. A bundle (dict) becomes a readable object, a list becomes a list, a tensory/model object that can't be JSON-serialized shows what it can.
• Nothing connected → shows None, which is itself useful: a None preview tells you the upstream node produced nothing or wasn't connected.

That "what is it actually" is the killer feature. ComfyUI's wildcard * wires hide types, and a huge fraction of beginner debugging is "I thought this was a string but it's a list" - Debug Any settles it in one glance.

Why it beats the alternatives

You can right-click and check, or add preview nodes, but those are per-type. Debug Any is one node for every type, which makes it the thing you slap on a wire when something misbehaves downstream and you want to see the actual payload before you start guessing. It's marked experimental and lives in the pack's Utils category alongside the other workflow-quality-of-life nodes - same spirit as rgthree's display/logger nodes, minimal footprint.

One honest note: it's a preview, not a logger. It shows you the value at the moment the graph runs; it won't keep a history across runs. For "what happened on the last queue" you'd want a logging node; for "what is this thing right now," this is it.

Install

Part of Nifty Nodes for ComfyUI. Manager: search "Nifty Nodes for ComfyUI" → Install → restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/Stibo/comfyui-nifty-nodes

Restart ComfyUI. No models, no dependencies. MIT-licensed, v3-API native, young pack (v2.1.0, mid-2026).

Gotchas

The main disappointment is with giant objects: a model or latent previews as something unhelpful because it can't be JSON-serialized - that's expected, don't fight it. And because it's an output node with no outputs, it sits at the end of a branch: it won't be in the middle of your data flow, and it doesn't pass anything along. If you want to inspect and keep the value flowing, put it on a parallel branch from the node you're curious about rather than in series.