IW PrintString

IW PrintString prints a string to ComfyUI's console - the terminal you launched ComfyUI from - prefixed with a label you choose. The author's own README line says it best: "would be nice if it went to the UI..." So no, this isn't a Show Text node. It's a debug print for people who live in the terminal.

Why you'd reach for it

Half of ComfyUI troubleshooting is just finding out what a node actually sent down a wire. A prompt that came out of a ReplaceString or a concat chain can look right in your head and be subtly wrong in practice - an extra newline, a swallowed space, a literal {} where a value should have been. Dropping a PrintString on that output and running once tells you the truth in a second. It's also genuinely handy for logging in batch jobs: prefix it with the batch index and you get a running record of what each iteration produced.

The one thing to keep straight is where the output lands. It does not appear in the browser UI - no toast, no widget, no image. You have to look at the terminal window where python main.py is running. If ComfyUI runs as a service or in a container, that means your service logs, not your browser. People get confused by this exactly once, and that once is usually this node.

The inputs

• input - the string to print (default "ComfyUI", wired input enabled so you can attach any STRING).
• prefix - a label printed before it (default "PrintString"), so you can tell which of several prints you're looking at. Change it to something meaningful like "PROMPT:" and your log becomes readable.

It's an output node with no outputs, which is correct - it's a terminal for your graph, not a pass-through.

A cheap alternative

If you genuinely want the value visible in the UI instead, pythongosssss's Show Text (from ComfyUI-Custom-Scripts) is the community standard and you'll be happier with it for that purpose. PrintString earns its keep when you want a log trail or when you're already working in a terminal. Neither is a bad choice; they're just different monitors.

Installing

cd ComfyUI/custom_nodes
git clone https://github.com/iwanders/ComfyUI_nodes

Restart ComfyUI, or grab it via ComfyUI Manager under iwanders. No dependencies, no downloads. Keep a workflow with a couple of these around - they're the fastest way to find out what your graph is really doing.