It can do all sorts of things: stop autoplaying videos, replace links with archive.is on newspapers, dim sidebars, or add small QOL features like editing the responses in chatgpt so it’s easier to copy/paste. Earlier today I asked it to add a “cost per 100 requests” column on OpenRouter’s activity page—decimals makes it hard for my ADHD brain to process.

Technically, you can do this with developer tools and user styles but i’ve been impressed with codex’ ability to take my vague requests and turn it into working styles with just 10% of the source page for context.

With an Apple dev account you can use it on mobile via Safari extensions.