Join String List

This is the mirror image of Split String to List from the same pack. Where that node takes one string and explodes it into a batch, Join String List takes a batch of strings and collapses it back into one - glued together with whatever separator you pick. If you've got a list of captions, tags, or per-item results floating around your graph and you need them as a single block of text again (to save, to log, to display), this is the node.

How it works

The node is declared with INPUT_IS_LIST = True, which is ComfyUI's signal to hand the function the entire incoming list in one call instead of running the node once per item. Internally it's just separator.join(texts) - Python's standard string join, run once over the whole list. (One implementation quirk worth knowing if you ever read the source: because the node runs in list mode, even the separator widget arrives wrapped in a one-item list, which is why you'll see separator[0] if you go looking. That's ComfyUI plumbing, not something you need to think about as a user.)

Inputs and outputs

• texts - the list of strings to join. This input is marked forceInput, meaning there's no widget for it - it has to come from a wire, not a typed value. Feed it from Split String to List, or any other node that outputs a list of strings.
• separator - what goes between each item when they're glued back together. Defaults to /.
• Output: TEXT - one single string (not a list this time).

How to install it

Comes with the same pack as the other TextUtils nodes:

• ComfyUI Manager: search "ComfyUI-TextUtils", install, restart.
• Manual: git clone https://github.com/wutipong/ComfyUI-TextUtils into ComfyUI/custom_nodes, restart.

No dependencies, no models - it's four plain Python files, nothing to pip install. There's no README in the repo either; everything here comes from actually reading the node's source rather than a doc that doesn't exist.

Common issues & troubleshooting

You can't type a value into texts. Because it's forceInput, there's no text box - just a socket. New users sometimes go looking for where to type their strings and come up empty; the fix is to wire in an upstream list-producing node instead. Split String to List (same pack) is the obvious pairing, but anything that outputs a list of strings works.

Joining a "list" of one item just hands you that item back unchanged. Not a bug - if only one string ever reaches this node, there's nothing to join, so don't be surprised if the output looks identical to the input.

Round-tripping isn't always lossless. If you split a string, edit some of the resulting items, and join it back with the same separator - and one of your edited items happens to contain that separator character itself - the joined result is ambiguous about where the original boundaries were. Pick a separator that won't show up inside your actual content if you plan to split-edit-join.

Mismatched separator between split and join. It's easy to split on one character and then join on the default / without noticing - check both nodes if the reassembled text looks wrong.