User agent
Updated 2026-07-11
Questions this answers
- What is a "user agent" and why does my AI keep mentioning it?
- How do I tell what devices and browsers my visitors are using?
- Why does AI suggest changing the user agent when I'm scraping or automating?
- Is it worth building an iPad version of my app?
The Fix
If you spend enough time around websites you'll run into the term user agent, and it's worth understanding.
Your user agent tells a website what browser you're using, what device you're on, and other details about your visit. It's one of the signals a site uses to understand who's visiting.
It matters for two reasons. First, marketing and analytics. This is genuinely useful data about who's on your site, where they're coming from, and what they're using. Wondering whether an iPad version is worth building? Your analytics can tell you. Tools like PostHog capture this, and AI can help you read it.
Second, web automation. When you're scraping or using a tool like Playwright, you'll often see AI suggest changing the user agent to mimic a different browser or device. Now you know what it's doing and why: it's changing how the site sees the visitor.
When to Use It
Keep this in your back pocket for two moments: when you're digging into who uses your product, and when you're automating a browser and something behaves differently than in your normal browser. In both cases the user agent is probably part of the story.