Perpend allows visitors to create dynamic prompts/presets for content generation. You can control the temperature/token settings as well. Supports GPT-3.5, GPT-3 (Davinci, Babbage, Curie, and Ada) & GPT-4 models. In short, a GUI for chat (with any model) + content generation + prompt library(inject/import/export).
PS: API key is stored on the client side.