User-Agent parser

Common use cases

• Decode User-Agent strings from server logs to see browser family, OS, and device class.
• Compare what your app thinks the client is versus what DevTools reports.
• Sanity-check bot or crawler signatures when filtering traffic.

Common mistakes to avoid

• Trusting User-Agent for security decisions alone

  Clients can spoof the header. Use it for analytics and hints, not for authentication.

• Expecting stable strings forever

  Browsers freeze or reduce detail over time. Log raw strings but avoid brittle substring checks.

• Confusing engine and browser brands

  Many browsers share an engine. Read both engine and product fields when diagnosing issues.

FAQ