GLOSSARY

What is a User-Agent string?

A User-Agent is the header your browser sends to identify itself. Learn how to read a UA string and parse yours free.

Open the User-Agent parser →All free tools

A User-Agent (UA) is a header your browser or HTTP client sends with every request, identifying the software, version, operating system, and device making the request. Servers use it to adapt responses and to detect bots.

Anatomy of a UA string

A typical UA looks like "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0 Safari/537.36". For historical reasons nearly every browser starts with "Mozilla/5.0" and mentions multiple engines — a legacy of feature-detection wars. A parser extracts the real browser, version, OS, and device from this soup.

What it is used for

Analytics, serving the right assets to a device, and bot detection all read the UA. It is trivially spoofable, so it is a hint, not proof — but combined with other signals it is useful for anti-abuse.

UA and scraping

When you scrape, sending a realistic UA (and rotating it) reduces the chance of being blocked. Many anti-bot systems flag default library UAs like "python-requests" immediately.

Try it now — free, no signup

Use the User-Agent parser in your browser. Then, when you need it at scale with an API key and higher limits, grab the full Eveses API.

Open the User-Agent parser →Sign up for the full API

FAQ

Why does every browser say Mozilla?›
A historical compatibility hack — early servers checked for "Mozilla" to send modern HTML, so every browser adopted it.
Can I change my User-Agent?›
Yes, it is client-controlled and easily set in any HTTP client or browser dev tools. That is why it cannot be trusted alone.

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