User Agent Parser Developer
Read a user-agent string, or inspect your own browser’s.
User Agent Parser is a free online tool that read a user-agent string, or inspect your own browser’s. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- Developer
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- None — it just works
- Works offline
- Yes, after the first visit
About User Agent Parser
User-agent strings are a fossil record. Nearly every browser still claims to be "Mozilla/5.0" for compatibility with 1990s sniffing code, and Chrome, Edge and Opera all identify as Safari and WebKit as well. Google has been actively freezing and reducing the string since 2021, replacing detail with User-Agent Client Hints — so the version and platform you read from it are increasingly approximate by design.
How to use it
- Paste the text you want to run through user agent parser.
- There is nothing to configure — the result updates as you type.
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
Questions
Why does every browser claim to be Mozilla?
Netscape's user agent began "Mozilla/", and sites checked for it before serving frames. Every subsequent browser copied the prefix to avoid being served a degraded page, and none has dared remove it since.
Should I detect features by user agent?
No. Test for the feature itself — `if ("share" in navigator)` — which is accurate, future-proof and immune to the string being frozen or spoofed.