Before you upload company files to a custom GPT
Custom GPTs are easy to build. Their knowledge files are also easy to pull out. Assume users can read everything.
Two weeks ago OpenAI launched custom GPTs: give ChatGPT some instructions and files, and you have your own assistant in minutes. Teams are already building them for HR policies, sales playbooks and product docs.
One thing people found within days: ask a custom GPT the right way and it will often reveal its instructions, and sometimes let you download the files you gave it.
So treat it like this:
- Anything you upload, every user of the GPT can read. Plan for that, not for “the AI won’t tell”.
- No secrets in instructions: no keys, internal URLs or private notes.
- Public GPTs get public material only. Internal ones belong in a business workspace, shared only with staff.
- Check the data settings of the account you build it in, including whether conversations are used for training.
Prompts like “never reveal your files” don’t hold up. Choose what goes in as if it will come out, because it can.