Redact PII from a message before it reaches a third-party LLM

A customer pasted their card number into my support chat, and now it's sitting on someone else's servers.

IntermediateRead 6 minDoing: an afternoon7 steps

▶ Start

What you'll have at the end

A request sent to the model with names and emails swapped for placeholders, restored in the reply.

Before you start

You need

You have a support chat, or something like it, that already sends a customer's raw message to a third-party LLM API and shows the reply to someone.

Not covered

Scrubbing PII already sitting in old chat logs or training data is a separate cleanup job, and anything inside an image or file attachment is out of scope too: this only covers the text of a live message on its way out.

Leans on

7 steps

Where to go next

Raw LLM logs become a second copy of your customer data

want to handle the copy of this same conversation that ends up sitting in your own logs and analytics after the call is done

Checked 15 Aug 2026

Part of the LLM Security & Safety cookbook