PyRIT Testing out Custom GPT

Hi Guys,

I am trying to figure out how I can use PyRIT to test out a custom chatgpt (using the openai gpt builder) built and if it is possible to do so?

Oct 30 '25 13:10 Om-Kamath

I have not tried this yet but you should be able to use OpenAI's chat completions API with custom GPTs. At least a brief search indicated as much. I am not linking any sources here since I couldn't find anything on OpenAI's pages.

If that's true, you can use OpenAIChatTarget and specify model name as the custom GPT's name. I would hope that by now they've made it accessible via responses API as well which would be OpenAIResponseTarget

Oct 31 '25 06:10 romanlutz

Read up on this. There's a page describing the difference: https://help.openai.com/en/articles/8673914-gpts-vs-assistants

In short: GPTs are just custom ChatGPTs which have no API. So if you want to test those with PyRIT you could check out PlaywrightTarget (see https://azure.github.io/PyRIT/code/targets/playwright_target.html). If you are trying to test the model behavior only you could recreate what a custom GPT does using the responses API as they describe in that post and test it using OpenAIResponseTarget from PyRIT.

Dec 07 '25 15:12 romanlutz