About this tool
What does it extract?
Browser, version, OS, device class and engine from User-Agent strings — for debugging reports, analytics cleanup and bot identification.
How to use it
- Paste a UA string to parse it instantly.
- Batch-parse log excerpts for overviews.
- Identify bots vs browsers vs apps.
Examples
- “Why does this break only for one customer?” — parse their UA.
- Splitting mobile vs desktop in raw logs.
- Spotting headless browsers in abuse traffic.
Important limitations
- UAs lie routinely (compatibility tokens, spoofing) — never trust for security decisions.
- Frozen UA strings (Chrome’s reduction) carry less signal every year.
- For capability decisions use feature detection, not parsing.
Privacy
Parsed locally. UA strings can be identifying in combination — handle log data accordingly.
Frequently asked questions
Why “Mozilla/5.0” everywhere?
1990s compatibility fossil every browser still emits.
Can I rely on it for blocking?
No — one header change bypasses it. Use auth and behavior signals.
What replaced it?
Client Hints (Sec-CH-UA-*) — structured, permission-gated, less fingerprintable.