PVL String Concat x3

String concatenation is the most boring operation in programming, and ComfyUI has a habit of making you rewire it every time. PVL String Concat x3 takes exactly three strings and joins them, end to end, with nothing added. That's the whole spec - which is precisely why it's useful: no surprise spaces, no separator you didn't ask for, just glue.

It ships in pvlprk/comfyui-pvl-api-nodes ("ComfyUI Assistant Node"), alongside a bigger sibling (Concat x8) and the rest of the pack's string toolkit. If you build prompts, filenames, or API payloads from parts, this is the node for it.

How it works

Three required string inputs (string_1, string_2, string_3), one output. The implementation is f"{string_1}{string_2}{string_3}" - direct concatenation, whitespace preserved exactly as given, nothing inserted.

That "nothing inserted" is the feature and the trap in one. If you want "hello world" out of "hello" and "world", you must put the space in one of the strings yourself ("hello " + "world"). The node never helps you with formatting. The upside is predictability: whatever you feed it, byte-for-byte, is what comes out, which makes it safe to use when a single accidental space would break a filename or a tag.

How you'll use it

The classic pattern is building a prompt or filename from parts that already know their own spacing. Take a base prompt from a text node, append a quality suffix from a dropdown, append a seed value - concat them and feed the result to whatever needs one string. Because the inputs are multiline, you can also paste full sentences per slot and just stack them, which beats trying to jam everything into one text box.

It's the natural partner to the pack's string utilities: split something apart with PVL Split String, rearrange, and rejoin here. For more than three pieces, the x8 variant does the same job with eight slots.

Installing

cd ComfyUI/custom_nodes
git clone https://github.com/pvlprk/comfyui-pvl-api-nodes

restart, or install via ComfyUI Manager (search "ComfyUI Assistant Node"). No models, no dependencies beyond Python's f-strings.

The honest caveats

• No auto-spaces, as advertised. Forgetting a trailing space on string_1 is the single most common mistake - the output looks "glued together" and you spend a minute finding the missing space.
• It's fixed at three. No variadic inputs; if you only have two parts, leave the third empty (an empty string concats to nothing, so that's fine).
• For joining a list of strings (from a loop or a batch), this isn't the right tool - the pack's PVL String List To String joins a list with a delimiter instead. Concat nodes are for a fixed, hand-wired set.