➡️ API Text Output

If you're a normal interactive user, this node does almost nothing visible - and that's fine, because it isn't for you. ➡️ API Text Output is for people driving ComfyUI through its HTTP API: send a workflow via /prompt, and you get back a response payload with the results from any node marked as an output node. This one's sole job is to make a string you care about - the exact prompt used, a seed, a generated filename, metadata - appear in that payload. The name is a lie only in the cute sense: it doesn't call any API and needs no key. It just labels a string as output so the API returns it.

How it works

It's a passthrough with paperwork. The input text is declared with forceInput: True, which is ComfyUI-speak for "this can be a widget you type in or a socket you wire from another node" - wire anything that outputs a string and the node flips to accepting the connection. When it runs, it coerces the value to a string, prints a [Fast Preview] Sending text string to API payload: ... line to the server console, and returns both a ui payload and a result. The ui payload is what lands in the API response and shows up in ComfyUI's execution history; the result is the pass-through STRING output you can also wire onward if you want.

What you actually set

• text - one input: the string. Type it in, or connect any STRING output to it (a Text Concatenate, a prompt text node, whatever).

That's the whole config surface. There's one output, also named STRING, which just echoes the value through. The node's is_output_node flag is what makes it show up in the API response, so you typically wire your final string into it and don't bother carrying the output anywhere else.

Installing it

Same story as the other node in this pack - the README lists Manager support as "Coming Soon" (i.e. not there yet), so clone it manually:

cd ComfyUI/custom_nodes
git clone https://github.com/AabhasTech/ComfyUI_Fast_Preview.git

Restart ComfyUI. It lives in the Fast Preview category, which reads a bit oddly for a text node until you remember it shipped in a preview-focused pack. No requirements.txt, no models, nothing to download - the pack's whole point is staying dependency-free.

Gotchas

The trap is expectations: in the interactive UI this node looks like it does nothing, because its output is invisible until you read the API response or the server console. If you're not consuming the workflow over the API, you probably want a plain text output or show-text node instead. And remember the README's framing: this was built for "Flow Worker"-style integrations that hit ComfyUI over HTTP - if that's your setup, this is the cleanest way to get a string back out of the payload. For the rest of us, it's a well-behaved, zero-cost utility to have in the pack.