String Case Converter

Sometimes a filename needs to be MODEL_XL, sometimes model_xl, and sometimes Model Xl. Doing that transformation in ComfyUI usually means a Python-expression node or an LLM call for something a one-line .upper() handles. String Case Converter is that one-liner, packaged: pick a case style, get the transformed string back.

It's a pure string utility - no files, no models, no state. It exists so your output filenames and prompt variables are consistently cased without you typing a regex.

How it works

Straightforward Python string methods under a dropdown. The case_type menu maps to five built-ins:

• upper - HELLO WORLD
• lower - hello world
• title - Hello World (every word's first letter capitalized)
• capitalize - Hello world (first letter only)
• swapcase - flips every letter's case, so Hello → hELLO

An empty input returns an empty string rather than erroring.

Inputs and outputs

• text - the string to convert (multiline allowed).
• case_type - the dropdown above.

Output: result - the converted string.

Install

Standard pack install - ComfyUI Manager (search "ComfyUI-AutoFlow") or:

cd ComfyUI/custom_nodes
git clone https://github.com/ZXL-Xinram/ComfyUI-AutoFlow

Restart after. No dependencies.

Where people get burned

• capitalize vs title. They look similar and aren't: title uppercases the start of every word, capitalize only the very first letter. Pick the wrong one and hello world becomes Hello world instead of Hello World.
• Unicode surprises. These are Python's Unicode-aware methods. title() has quirks with apostrophes ("don't" → "Don'T"), which is standard behavior but occasionally ugly in filenames.
• It doesn't trim whitespace. Leading/trailing spaces survive the conversion. If that matters, trim upstream.

Honestly, this is the kind of node you install once, use for a filename, and forget - but that's fine. It's the difference between hand-casing strings mid-graph and having a place to point at when a workflow demands consistent casing.