User-Agent Parser
The /agent endpoint parses a User-Agent string and returns structured information about the browser, operating system, device, rendering engine, and whether the client is a bot. If no UA is provided, the request's own User-Agent header is used.
GET/v4/agent
Use Cases
Detect the browser and OS of your visitors, identify bots and crawlers, serve device-specific content (mobile vs desktop), or log structured client metadata from raw User-Agent strings.
Parameters
| Parameter | Required | Description |
|---|---|---|
ua | No | Raw User-Agent string to parse. Defaults to the request's User-Agent header. |
Response Fields
| Field | Type | Description |
|---|---|---|
raw | string | The original User-Agent string |
browser.name | string | Detected browser name (e.g. Chrome, Firefox, Safari) |
browser.version | string | Full browser version |
browser.major | string | Major version number only |
os.name | string | Operating system name (e.g. macOS, Windows 10/11, iOS) |
os.version | string | OS version string |
device.type | string | Device category: desktop, mobile, or tablet |
device.vendor | string | Device manufacturer (e.g. Apple, Samsung, Google) |
engine.name | string | Rendering engine (e.g. Blink, Gecko, WebKit) |
engine.version | string | Engine version |
bot | boolean | true if the UA matches a known bot or crawler pattern |
Code Examples
curl -X GET \
"https://api.sylvain.sh/v4/agent"Try It
Error Handling
| Error Message | Description |
|---|---|
A User-Agent string is required. | The ua parameter is empty and no User-Agent header was sent |