userstack

userstack is a Go client library for the apilayer userstack service; returning instant user-agent string lookups.

To use this client you will need an API access key. The free tier supports 10,000 monthly lookups, but over http-only. To get HTTPS Encryption you need a Basic plan or higher 🤷‍♂️.

The official documentation is found here.

If you are on a free account, initialize the client with secure false. Otherwise you'll get a 105 error:

Access Restricted - Your current Subscription Plan does not support HTTPS Encryption.

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Technical bits:

Well-defined types are available: entity, device, category and api error.

Users can supply their own HTTP Client implementation through options, otherwise a default client is used.

Users can propogate a context, otherwise context.Background() is used by default.

This package may return a custom error, *ApiErr, which callers can assert to get at the raw code, type and info. If using go1.13 use errors.As for assertions, otherwise a regular type switch will do. Especially useful for 104 or ErrUsageLimitReached errors: monthly usage limit has been exceeded.

Crawler information is only available for Basic Plan or higher. So if you don't see this in the response, check your plan.

Example usage - single lookup (HTTP GET)

client, err := userstack.NewClient(key, false)
if err != nil {
    // handler err
}

ua := "Mozilla/5.0 (Linux; Android 9; Pixel 2 Build/PQ3A.190801.002; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/76.0.3809.132 Mobile Safari/537.36 Instagram 109.0.0.18.124 Android (28/9; 420dpi; 1080x1794; Google/google; Pixel 2; walleye; walleye; en_US; 170693979)"

// context.Background() used internally if nil ctx is supplied.
stack, err := client.Detect(nil, ua) 
if err != nil {
    var e *userstack.ApiErr
    if errors.As(err, &e) { 
        // handler error of type ApiErr
    }
    // handler err
}

fmt.Printf("device: %s\nentity: %s\ncrawler: %s", stack.Device.Type, stack.Type, stack.Crawler.Category)
// device: smartphone
// entity: mobile-browser
// crawler: unknown