I was surprised to see something was in text today, until I remembered knowing it at some point - the .har format. Looking at simonw's Claude-generated script [1] to investigate AI agent sent emails [2] by extracting .har archives, I saw that it uses base64 for binary and JSON strings for text.

It might be a good bet to bet on text, but it feels inefficient a lot of the time, especially in cases like this where all sorts of files are stored in JSON documents.

1: https://gist.github.com/simonw/007c628ceb84d0da0795b57af7b74...

2: https://simonwillison.net/2025/Dec/26/slop-acts-of-kindness/