Join String List

Once you start building prompts out of reusable pieces - a Const String here, a Load Preset there, a subject string from somewhere else entirely - you eventually need one node to glue them all back into a single string before it hits CLIP Text Encode. That's the whole job of Join String List: give it a separator, feed it strings, get one string back.

How it works

You set a separator (defaults to ", "), and the node concatenates whatever string arguments you've connected, separator between each. The README only shows a single arg1 slot in the base schema, but describes the behavior generically as joining argN strings - which lines up with the common ComfyUI pattern where a node's input list grows as you plug more connections into it, rather than you pre-declaring a fixed count. In practice: connect one string, a second slot should appear for the next, and so on.

Straightforward, but worth flagging plainly: the author marks this node Experimental, in their own words, "there may be some bugs as we have not been able to check the operation very well." That's not me being cautious for you - that's the README.

Inputs and outputs that matter

• separator - required string, the glue between pieces. Default , gives you standard comma-space tag formatting.
• arg1 (and however many more slots appear as you connect) - the strings to join, in order.

Output is a single joined STRING, ready for a CLIP Text Encode or another string node downstream.

Installing it

ComfyUI Manager → search ComfyUI-PromptUtilities → install → restart. Or clone it directly:

cd ComfyUI/custom_nodes && git clone https://github.com/nkchocoai/ComfyUI-PromptUtilities

No models, no heavy dependencies - it's a small pack of pure string-manipulation nodes, and this is one of the simpler ones in it. You'll find it under the PromptUtilities category once you restart.

Where people get burned

Given the author's own "experimental, not thoroughly checked" caveat, the sane move is to test this on a couple of static strings before wiring it into anything you're batch-running. Watch specifically for how empty or disconnected arg slots behave - a node like this can either skip them cleanly or leave you with a stray separator (tag1, , tag3) sitting in your final prompt, and the README doesn't say which.

If you just need two or three fixed strings glued together with literal text between and around them - not just a repeated separator - this pack's Format String node is the better fit: it lets you place args wherever you want inside a template ([1] wearing [2]) instead of always joining them the same way. And if you want something more battle-tested for combining and displaying strings generally, the README itself recommends pairing this pack with ComfyUI-Custom-Scripts' String Function and Show Text nodes, which is a good sign the author sees this one as a lightweight option rather than the last word on string joining.