Go / Golang Client

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "io/ioutil"
    "net/http"
)

// Response defines the structure of the JSON response from Gender-API.com
type Response struct {
    ResultFound bool    `json:"result_found"`
    FirstName   string  `json:"first_name"`
    Gender      string  `json:"gender"`
    Probability float64 `json:"probability"`
}

func main() {
    // Determine the gender of a first name using API V2
    // ---------------------------------------------------
    apiKey := "YOUR_API_KEY" // Get your key at https://gender-api.com/en/account/auth-tokens
    firstName := "Theresa"

    // Construct the JSON payload
    requestBody, _ := json.Marshal(map[string]string{
        "first_name": firstName,
    })

    // Create the request
    req, err := http.NewRequest("POST", "https://gender-api.com/v2/gender/by-first-name", bytes.NewBuffer(requestBody))
    if err != nil {
        fmt.Printf("Error creating request: %s\n", err)
        return
    }

    // Set headers
    req.Header.Set("Content-Type", "application/json")
    req.Header.Set("Authorization", "Bearer "+apiKey)

    // Perform the request
    client := &http.Client{}
    resp, err := client.Do(req)
    if err != nil {
        fmt.Printf("Error making request: %s\n", err)
        return
    }
    defer resp.Body.Close()

    // Read the response body
    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
        fmt.Printf("Error reading response: %s\n", err)
        return
    }

    // Parse the JSON response
    var result Response
    if err := json.Unmarshal(body, &result); err != nil {
        fmt.Printf("Error parsing JSON: %s\n", err)
        return
    }

    // Output the result
    fmt.Printf("Name: %s\n", result.FirstName)
    fmt.Printf("Gender: %s\n", result.Gender)
    fmt.Printf("Probability: %.2f\n", result.Probability)
}