Java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class CpfLookup {
    public static void main(String[] args) throws Exception {
        String cpf    = "12345678909";
        String apiKey = System.getenv("CPFHUB_API_KEY");

        HttpClient client = HttpClient.newHttpClient();

        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://api.cpfhub.io/cpf/" + cpf))
            .header("x-api-key", apiKey)
            .GET()
            .build();

        HttpResponse<String> response = client.send(
            request,
            HttpResponse.BodyHandlers.ofString()
        );

        if (response.statusCode() != 200) {
            throw new RuntimeException("API error: " + response.statusCode());
        }

        System.out.println(response.body());
        // {"data":{"cpf":"12345678909","name":"Fulano de Tal",...}}
    }
}

// pom.xml: com.fasterxml.jackson.core:jackson-databind:2.16.1

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

ObjectMapper mapper = new ObjectMapper();
JsonNode root = mapper.readTree(response.body());
JsonNode data = root.get("data");

System.out.println(data.get("name").asText());       // "Fulano de Tal"
System.out.println(data.get("birthDate").asText());  // "15/06/1990"
System.out.println(data.get("gender").asText());     // "M"