Firefox for Android user agent string
Firefox for Android reports the device's real Android major version (versions below 10 are reported as 10; "16" here is an example) and repeats the Firefox version in the Gecko/ token. It sends no device model. Below is a sample user agent string and what each part means.
Mozilla/5.0 (Android 16; Mobile; rv:158.0) Gecko/158.0 Firefox/158.0
At a glance
| Browser | Firefox 158.0 |
| Engine | Gecko 158.0 |
| Operating system | Android 16 |
| Device | Phone |
String breakdown
| Fragment | Meaning |
|---|---|
Mozilla/5.0 | Historical compatibility token. Nearly every browser claims "Mozilla/5.0" so that old servers do not serve it broken pages. |
Android 16 | Android 16. |
Mobile | Mobile device marker — sites use it to serve the mobile layout. |
rv:158.0 | Revision/version marker: 158.0. |
Gecko/158.0 | Gecko engine token 158.0. Desktop Firefox freezes it at 20100101. |
Firefox/158.0 | Firefox, version 158.0. |
Other forms of this user agent
Desktop mode
Mozilla/5.0 (X11; Linux x86_64; rv:158.0) Gecko/20100101 Firefox/158.0Use it in code
curl
curl -A "Mozilla/5.0 (Android 16; Mobile; rv:158.0) Gecko/158.0 Firefox/158.0" https://example.comPython (requests)
import requests
requests.get("https://example.com", headers={"User-Agent": "Mozilla/5.0 (Android 16; Mobile; rv:158.0) Gecko/158.0 Firefox/158.0"})Playwright (Node.js)
const context = await browser.newContext({ userAgent: "Mozilla/5.0 (Android 16; Mobile; rv:158.0) Gecko/158.0 Firefox/158.0" });Source: Firefox user agent string reference · checked September 2026