String Concatenator

Building text in ComfyUI is all concatenation: a prompt prefix plus a subject, a base filename plus an index, a folder plus a save name. String Concatenator is the plainest possible version of that - two strings in, one string out, with a separator field that actually lets you control the glue.

The separator is what separates this from the pack's other options: most string-join nodes force you to embed the separator in one of the strings, which is exactly where a typo lives. Here it's a first-class field.

How it works

It's string_a + separator + string_b, nothing clever. A few defensive touches: None values get coerced to empty strings, so a disconnected input won't crash the graph - you just get a shorter result than you expected. The separator defaults to empty, so if you want a space or a hyphen you have to type it.

Inputs

• string_a - first string.
• string_b - second string.
• separator - inserted between them. Default empty; put , _, -, whatever you need.

Output

result - the joined string.

Install

Standard pack install - ComfyUI Manager (search "ComfyUI-AutoFlow") or:

cd ComfyUI/custom_nodes
git clone https://github.com/ZXL-Xinram/ComfyUI-AutoFlow

Restart after. No dependencies.

Where people get burned

• The empty default separator. "hello" + "" + "world" = "helloworld". If that's not what you wanted, remember the separator isn't automatic - you have to set it.
• It's exactly two strings. More than two? The pack's Multi String Concatenator takes up to five. Fewer? Then you barely need this node.
• Disconnected inputs silently vanish. Leave string_b unconnected and you get string_a back, not an error. Usually convenient, occasionally confusing.

It's the most basic node in the pack, and that's the right description - some utilities are just "make this string out of these two strings," and this does it without a regex or a formatting syntax you have to remember.