API DOCUMENTATION V2

Phone validation and formatting with API v2

Validate and format international or national phone numbers with GenderAPI v2. See required country context, JSON fields and the one-credit charge.

Validate and format a phone number

POST /phone/validate accepts number and optional country. Use an international number beginning with +, or supply an uppercase ISO country for a national number. The response contains valid, possible, e164, country and country_calling_code inside data, plus the same meta envelope. This checks number structure, not subscriber existence. A completed validation costs 1 credit, including invalid results. The synthetic response below illustrates an invalid number, independently of the request example.

JSON fieldTypeRule
numberstringRequired, 3–32 characters. ASCII digits, spaces, parentheses and hyphens, with an optional leading +. Extensions and alphabetic characters are not accepted.
countrystringUppercase ISO 3166-1 alpha-2 code. Required for a national number; optional when number starts with +. Omit if unused.

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.

Error and retry guide →
cURL
curl --silent --show-error --fail-with-body --max-time 30 \
  --request POST 'https://api.genderapi.io/api/v2/phone/validate' \
  --header "Authorization: Bearer ${GENDERAPI_API_KEY:?Set GENDERAPI_API_KEY}" \
  --header 'Content-Type: application/json' \
  --data '{
  "number": "+905321234567"
}'

cURL 7.76+ in a POSIX shell. Run in your terminal. Runtime documentation

JavaScript / Node.js
// 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 = {
  "number": "+905321234567"
};

const response = await fetch("https://api.genderapi.io/api/v2/phone/validate", {
  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 json
import os
import sys
import urllib.error
import urllib.request

api_key = os.environ.get("GENDERAPI_API_KEY")
if not api_key:
    raise RuntimeError("Set GENDERAPI_API_KEY")
body = json.loads("{\"number\":\"+905321234567\"}")

class NoRedirect(urllib.request.HTTPRedirectHandler):
    def redirect_request(self, req, fp, code, msg, headers, newurl):
        return None

request = urllib.request.Request(
    "https://api.genderapi.io/api/v2/phone/validate",
    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
<?php
$apiKey = getenv('GENDERAPI_API_KEY');
if (!$apiKey) {
    throw new RuntimeException('Set GENDERAPI_API_KEY');
}
$body = json_decode('{"number":"+905321234567"}', true, 512, JSON_THROW_ON_ERROR);

$ch = curl_init('https://api.genderapi.io/api/v2/phone/validate');
curl_setopt_array($ch, [
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_FOLLOWLOCATION => false,
    CURLOPT_TIMEOUT => 30,
    CURLOPT_HTTPHEADER => [
        'Authorization: Bearer ' . $apiKey,
        'Content-Type: application/json',
    ],
    CURLOPT_POSTFIELDS => json_encode($body, JSON_THROW_ON_ERROR),
]);
$raw = curl_exec($ch);
if ($raw === false) {
    throw new RuntimeException(curl_error($ch));
}
$status = curl_getinfo($ch, CURLINFO_HTTP_CODE);
$contentType = curl_getinfo($ch, CURLINFO_CONTENT_TYPE) ?: '';
curl_close($ch);
if (strpos($contentType, 'json') === false) {
    throw new RuntimeException("HTTP $status: expected a JSON response");
}
$result = json_decode($raw, true, 512, JSON_THROW_ON_ERROR);
$output = json_encode($result, JSON_PRETTY_PRINT | JSON_THROW_ON_ERROR) . PHP_EOL;
if ($status < 200 || $status >= 300) {
    fwrite(STDERR, $output); // Preserve the Problem Details body.
    exit(1);
}
echo $output;
// For batches, inspect every item; HTTP 200 can contain item errors.

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 = "{\"number\":\"+905321234567\"}";
        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/phone/validate"))
            .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/phone/validate");
request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);
request.Content = new StringContent("{\"number\":\"+905321234567\"}", 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 main

import (
    "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 := "{\"number\":\"+905321234567\"}"
    request, err := http.NewRequest("POST", "https://api.genderapi.io/api/v2/phone/validate", 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

Illustrative JSON response
{
  "data": {
    "valid": false,
    "possible": false,
    "e164": null,
    "country": null,
    "country_calling_code": null
  },
  "meta": {
    "request_id": "11111111-1111-4111-8111-111111111111",
    "duration_ms": 12,
    "access": {
      "mode": "ip_trial",
      "reason": "api_key_missing"
    },
    "usage": {
      "charged_credits": 1,
      "remaining_credits": 7,
      "billing_status": "confirmed",
      "resets_at": "2026-09-26T12:00:00.000Z",
      "limit": 10,
      "period_seconds": 86400
    }
  }
}

Read phone validation fields

A 422 response rejects malformed input before billing. A well-formed request whose number cannot be parsed can complete with HTTP 200, valid: false and null formatting fields; that completed validation costs 1 credit. A parseable but invalid number may still have an e164 value. Check valid rather than treating formatted output as proof of validity.

Field inside dataMeaning
validWhether the number matches the numbering-plan validation rules.
possibleWhether the number has a plausible length for its numbering plan; weaker than valid.
e164International formatted number when parsing succeeds, otherwise null.
countryRegion derived from the number, or null when unavailable; it does not locate the subscriber.
country_calling_codeNumeric international calling code, or null when unavailable.

Authentication and retries

Send your existing Bearer API key and Content-Type: application/json. The code examples read GENDERAPI_API_KEY from the environment. National numbers require country; this field is optional when number begins with +.