Text Mixer (Concat)

Text Mixer (Concat) is a whole pack that does exactly one thing: it joins several text strings into one string, with a separator you pick. That's it. No API calls, no model files, no Python dependencies beyond the standard library - the entire node is about 30 lines of Python plus a small bit of JavaScript that makes the input slots auto-expand. If you've ever found yourself building prompts from reusable blocks - a fixed subject line, a style block, a stack of quality tags - and getting sick of retyping them into one giant text box, this is the node that lets you stop.

ComfyUI core gives you text boxes, not a clean way to splice several of them into one string. You can't wire a string into a CLIPTextEncode prompt field the way you wire images around - text fields are typed, so the moment you want to assemble a prompt from parts, you're doing it by hand every time. That's the gap this node sits in. And with the newer LLM-encoded models where the community now recommends structuring prompts in blocks rather than one comma-soup line, a node that joins blocks with a newline separator is genuinely useful, not a gimmick.

How it works

Under the hood the node collects every input named txt_1, txt_2, and so on, drops the ones that are empty, and joins the rest with whatever separator you chose. The mapping is exactly what you'd expect: newline → one line break, paragraph → a blank line, space → a space, comma → comma-space, and none → nothing, jammed together. The single text output is a plain STRING, so it plugs straight into a CLIP text encoder, a prompt field, a Show Text node, or anything else that eats a string.

The pack's real trick is in the frontend. A spare input slot always sits at the end of the node. Connect a wire to it and a new empty slot appears; disconnect one and the empty ones get removed and the rest renumber themselves. It's a small quality-of-life detail, but it's why this beats a fixed-slot node for prompt work - you add a block without hunting for a config toggle.

The inputs that matter

Only one is required: separator, an enum with the five choices above. The rest is the txt_1, txt_2, … inputs you connect. The two things a beginner actually needs to know:

• You can't type into this node. The text slots are marked forceInput, so they're pure input ports. You wire strings in from a text node - the built-in multiline text node, a Show Text, or any custom node that emits STRING - or you're staring at a node that does nothing.
• Empty slots are silently skipped. Leave txt_2 disconnected and it vanishes from the join, so you never get stray separators. Side effect: if you genuinely want a blank line in the middle of your output, you can't produce one by leaving a slot empty. Feed it a space if you're that desperate.

The comma separator adds a trailing space after the comma - that's the author's choice, not a bug.

Installing it

Zero friction. It ships no requirements.txt and needs no model downloads, which in the custom-node ecosystem is about as rare as a node that works on the first try. Through ComfyUI Manager, search "comfyui_txt_mixer" (or "Text Mixer") and install. Or do it by hand:

cd ComfyUI/custom_nodes
git clone https://github.com/stevanisya/comfyui_txt_mixer

Then restart ComfyUI. The node lives under the UnaCustom category in the node menu - an odd name, but it's the author's own folder, so don't go hunting for "Text" or "Utils".

Gotchas

Because the auto-expanding slots are handled by the JS side, the node needs its extension to actually load. If you install it and the spare slot never appears, hard-refresh the browser tab or restart ComfyUI - the Python side works either way, but the expand-and-renumber behavior won't. And the pack is so obscure that community docs basically don't exist for it, so when in doubt, trust the behavior above: it's dead simple, and what you see is what you get.

For a tiny single-node pack this punches exactly where you'd want it: modular prompts, shared blocks, one clean string out. It won't change your life, but it will stop you from retyping your style block for the hundredth time.