List Combine Node (zer0)

Some nodes hand you a list of strings, and most of ComfyUI's text inputs want a single string. The List Combine Node (zer0) is the bridge between the two: it takes a list, joins every item with a separator you choose, and spits out one combined string. That's the whole job, and it does it without drama.

Its home turf is the prompt-splitting workflow. This node comes from the same pack as the Prompt Minimizer And Splitter, and the README says it plainly: it's "intended for use with a tokenizer + prompt splitter." You split a long prompt into token-sized chunks, then recombine them with BREAK so the CLIP encoder treats each chunk as its own unit. It'll join anything that returns a list of strings, though - it's not picky.

How it works

Under the hood it's a one-liner: separator.join(input_list). The interesting part is that input_list is a wildcard (*) input marked as a list, which is ComfyUI's way of saying "give me all the items at once, not one item per graph run." That's why the wire into it comes from a splitter or a list-returning node, not from a plain text box. The separator and the integer control arrive alongside it, and everything gets joined in list order.

Three inputs, and only the middle one will ever surprise you:

• input_list - the list of strings to concatenate. Wire it from whatever produced the list.
• combine_last_x_items - default 1. If you set it higher, the last X items get mashed together with no separator first, then the whole thing is joined. The tooltip calls it out: it exists "for correcting unnecessary separators." If your splitter leaves a trailing empty tag, bumping this to 2 swallows it instead of leaving a stray BREAK at the end.
• separator - default " BREAK ", with the spaces. This is the string inserted between every item. Change it to ", " and the node quietly becomes a list-of-tags joiner.

There's one output: Combined String, a plain STRING you can feed into a CLIP Text Encode, a prompt widget, or anything else that eats text.

A word about BREAK

The default separator is a CLIP-era tool. BREAK forces a split at the 77-token chunk boundary, and it does real work on the SD 1.5/SDXL lineage - Illustrious, Pony, NoobAI, WAI and friends. On LLM-encoded models (Flux 2 Klein, Z-Image, Anima) there is no chunk boundary left to break against, so BREAK in the joined string is basically inert. If you're on a modern model and you only joined for bookkeeping, swap the separator for ", " and move on.

Install

Same story as the rest of this pack - no models, no heavy dependencies, just one Python package:

cd ComfyUI/custom_nodes
git clone https://github.com/zer0thgear/zer0-comfy-utils

Restart ComfyUI and the node appears under the text utility category. Easier still: ComfyUI Manager → Install Custom Nodes → search "zer0 Comfy Utilities" and let it handle everything, including the pack's single tiktoken dependency. If you cloned by hand, run pip install -r requirements.txt from inside custom_nodes/zer0-comfy-utils - a missing tiktoken breaks the whole pack's import, not just the splitter that uses it.

This is a small personal pack (the author calls it "dubiously useful nodes that I've made for my own use"), last touched in early 2025, so don't expect weekly updates. For a job this small, that's fine - the node is four lines of logic. It won't rot.