Predict from usernames and nicknames with GenderAPI v2. Learn forceToGenderize, dataset-first lookup, AI response fields and the 1 or 2 credit tariff.
Before sending the request
Send JSON to POST https://api.genderapi.io/api/v2/gender. Use your existing API key in Authorization: Bearer YOUR_API_KEY and Content-Type: application/json. Every request is processed independently.
Choose your language in the code example. Set GENDERAPI_API_KEY in the process environment before running it. Missing or unrecognized keys can use the shared IP trial, so confirm meta.access.mode is api_key when integrating an account.
Use type: username for handles and nicknames. Set forceToGenderize to true when you want an attempt based on nickname semantics, such as prenses, even if no real name can be extracted. The dataset is still checked first. A nickname prediction may return a non-null gender with name: null.
Choose your language.Set up your API key, then run the example on your server.
Every prediction request is a new billable operation, including retries. These examples do not automatically retry. Check billing status before sending another request.
Before you run: access and error handling
Run these examples on your server. Set GENDERAPI_API_KEY in the process environment to your existing API key. Confirm meta.access.mode is api_key: an unrecognized key can fall back to the IP trial.
HTTP 4xx and 5xx JSON responses preserve the error body and return a nonzero exit status. Check code, action and meta.usage.billing_status before retrying.
// Server-side Node.js. Save as example.mjs.const apiKey = process.env.GENDERAPI_API_KEY;if (!apiKey) throw new Error("Set GENDERAPI_API_KEY");const body = { "type": "username", "value": "prenses", "country": "TR", "forceToGenderize": true};const response = await fetch("https://api.genderapi.io/api/v2/gender", { method: "POST", headers: { Authorization: `Bearer ${apiKey}`, "Content-Type": "application/json", }, body: JSON.stringify(body), signal: AbortSignal.timeout(30_000), redirect: "error",});const raw = await response.text();if (!(response.headers.get("content-type") ?? "").includes("json")) { throw new Error(`HTTP ${response.status}: expected JSON; request ID ${response.headers.get("x-request-id")}`);}const result = JSON.parse(raw); // Also accepts application/problem+json.if (!response.ok) { console.error(`HTTP ${response.status}`, result); process.exitCode = 1; // A retry is a new operation; inspect billing first.} else { console.log(JSON.stringify(result, null, 2)); // For batches, inspect every item: HTTP 200 may contain item errors.}
Node.js 22+; built-in fetch. Save as example.mjs and run node example.mjs. Runtime documentation
Python
import jsonimport osimport sysimport urllib.errorimport urllib.requestapi_key = os.environ.get("GENDERAPI_API_KEY")if not api_key: raise RuntimeError("Set GENDERAPI_API_KEY")body = json.loads("{\"type\":\"username\",\"value\":\"prenses\",\"country\":\"TR\",\"forceToGenderize\":true}")class NoRedirect(urllib.request.HTTPRedirectHandler): def redirect_request(self, req, fp, code, msg, headers, newurl): return Nonerequest = urllib.request.Request( "https://api.genderapi.io/api/v2/gender", method="POST", data=json.dumps(body).encode("utf-8"), headers={ "Authorization": "Bearer " + api_key, "Content-Type": "application/json", },)opener = urllib.request.build_opener(NoRedirect())try: response = opener.open(request, timeout=30)except urllib.error.HTTPError as error: response = error # Keep the Problem Details body on non-2xx responses.with response: status = response.status raw = response.read().decode("utf-8") if "json" not in response.headers.get("Content-Type", ""): raise RuntimeError(f"HTTP {status}: expected a JSON response") result = json.loads(raw)print(json.dumps(result, indent=2), file=sys.stderr if status >= 300 else sys.stdout)if not 200 <= status < 300: sys.exit(1) # Inspect code, action and billing before retrying.# For batches, inspect every item even when HTTP status is 200.
Python 3.10+; standard library. Save as example.py and run python3 example.py. Runtime documentation
PHP 8+ with the cURL extension. Save as example.php and run php example.php. Runtime documentation
Java
import java.net.URI;import java.net.http.HttpClient;import java.net.http.HttpRequest;import java.net.http.HttpResponse;import java.nio.charset.StandardCharsets;import java.time.Duration;public class GenderApiExample { private static String requiredEnv(String name) { String value = System.getenv(name); if (value == null || value.isBlank()) throw new IllegalStateException("Set " + name); return value; } public static void main(String[] args) throws Exception { String apiKey = requiredEnv("GENDERAPI_API_KEY"); String body = "{\"type\":\"username\",\"value\":\"prenses\",\"country\":\"TR\",\"forceToGenderize\":true}"; HttpClient client = HttpClient.newBuilder() .connectTimeout(Duration.ofSeconds(10)) .followRedirects(HttpClient.Redirect.NEVER) .build(); HttpRequest request = HttpRequest.newBuilder(URI.create("https://api.genderapi.io/api/v2/gender")) .timeout(Duration.ofSeconds(30)) .header("Authorization", "Bearer " + apiKey) .header("Content-Type", "application/json") .POST(HttpRequest.BodyPublishers.ofString(body, StandardCharsets.UTF_8)) .build(); HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString(StandardCharsets.UTF_8)); if (!response.headers().firstValue("content-type").orElse("").contains("json")) { throw new IllegalStateException("HTTP " + response.statusCode() + ": expected JSON"); } // JSON text; parse with your application's JSON library when integrating. if (response.statusCode() < 200 || response.statusCode() >= 300) { System.err.println(response.body()); // Includes Problem Details. System.exit(1); } System.out.println(response.body()); // For batches, inspect each item's data or error, including on HTTP 200. }}
Java 17+; standard HTTP client. Save as GenderApiExample.java and run java GenderApiExample.java. Runtime documentation
C# / .NET
using System;using System.Net.Http;using System.Net.Http.Headers;using System.Text;using System.Text.Json;string RequiredEnv(string name) => !string.IsNullOrWhiteSpace(Environment.GetEnvironmentVariable(name)) ? Environment.GetEnvironmentVariable(name)! : throw new InvalidOperationException($"Set {name}");var apiKey = RequiredEnv("GENDERAPI_API_KEY");using var handler = new HttpClientHandler { AllowAutoRedirect = false };using var client = new HttpClient(handler) { Timeout = TimeSpan.FromSeconds(30) };using var request = new HttpRequestMessage(HttpMethod.Post, "https://api.genderapi.io/api/v2/gender");request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);request.Content = new StringContent("{\"type\":\"username\",\"value\":\"prenses\",\"country\":\"TR\",\"forceToGenderize\":true}", Encoding.UTF8, "application/json");using var response = await client.SendAsync(request);var raw = await response.Content.ReadAsStringAsync();if (!(response.Content.Headers.ContentType?.MediaType?.Contains("json") ?? false)) throw new InvalidOperationException($"HTTP {(int)response.StatusCode}: expected JSON");using var result = JsonDocument.Parse(raw);if (!response.IsSuccessStatusCode){ Console.Error.WriteLine(result.RootElement); // Preserve Problem Details. Environment.ExitCode = 1;}else{ Console.WriteLine(result.RootElement); // For batches, inspect every item even on HTTP 200.}
.NET 8+ console application. Use as Program.cs in a console project, then run dotnet run. Runtime documentation
Go
package mainimport ( "encoding/json" "fmt" "io" "net/http" "os" "strings" "time")func requiredEnv(name string) string { value := os.Getenv(name) if value == "" { panic("Set " + name) } return value}func run() error { apiKey := requiredEnv("GENDERAPI_API_KEY") body := "{\"type\":\"username\",\"value\":\"prenses\",\"country\":\"TR\",\"forceToGenderize\":true}" request, err := http.NewRequest("POST", "https://api.genderapi.io/api/v2/gender", strings.NewReader(body)) if err != nil { return err } request.Header.Set("Authorization", "Bearer " + apiKey) request.Header.Set("Content-Type", "application/json") client := &http.Client{ Timeout: 30 * time.Second, CheckRedirect: func(req *http.Request, via []*http.Request) error { return http.ErrUseLastResponse }, } response, err := client.Do(request) if err != nil { return err } defer response.Body.Close() raw, err := io.ReadAll(response.Body) if err != nil { return err } if !strings.Contains(response.Header.Get("Content-Type"), "json") || !json.Valid(raw) { return fmt.Errorf("HTTP %d: expected a JSON response", response.StatusCode) } if response.StatusCode < 200 || response.StatusCode >= 300 { return fmt.Errorf("HTTP %d: %s", response.StatusCode, raw) } fmt.Println(string(raw)) // For batches, inspect every item even on HTTP 200. return nil}func main() { if err := run(); err != nil { fmt.Fprintln(os.Stderr, err) // Keep Problem Details for error handling. os.Exit(1) }}
Go 1.22+; standard library. Save as main.go and run go run main.go. Runtime documentation
Example response
This synthetic response illustrates the JSON shape, not measured accuracy or a guaranteed live result. It shows IP-trial access; an authenticated operation reports meta.access.mode: api_key and null trial-only quota fields. Read data for the inference and meta.usage for the operation's billing outcome.
The example uses forceToGenderize: true. A resolved dataset lookup costs 1 credit. If unresolved, the API asks AI to interpret the alias and charges 2 credits total for a successful operation, including an unknown result. Omit ai_mode or set it to fallback; off and always conflict with forceToGenderize and return 422.
An inferred gender with name: null is allowed in nickname mode. This means no real given name was extracted; it is not a parser error. AI results have sample_count: null and confidence_kind: model_reported when a gender is returned. The score is not a calibrated probability or verified identity.
Without forceToGenderize, a single username lookup still defaults to ordinary AI fallback for 1 credit total, but it requires a usable real given name. Use options.ai_mode: off for dataset-only processing.