cURL to Java

What is curl-to-Java?

This tool converts a curl command into Java code using java.net.http.HttpClient — the HTTP client that's been built into the JDK itself since Java 11, so the output needs no OkHttp, Apache HttpClient, or any other dependency to compile and run.

How it works

The curl command is parsed into method, URL, headers, body, form fields, and auth by the same parser every cURL converter on this site shares. Headers map onto HttpRequest.Builder.header(...) calls, and the body is passed to BodyPublishers.ofString(...) as a raw string — never re-parsed and reconstructed as a Java object, so the exact payload curl would send is preserved byte for byte. -u user:pass becomes a manually built Authorization header using Base64.getEncoder().encodeToString(...), since HttpClient has no dedicated Basic Auth helper the way some higher-level clients do.

Features

• Zero external dependencies — java.net.http.HttpClient ships with the JDK (Java 11+)
• Body passed through as a raw string, not re-encoded
• -u Basic Auth computed via Base64.getEncoder()
• Synchronous request via client.send(...), printing status code and body
• -F/--form uploads listed explicitly as a comment rather than a guessed multipart implementation

Example

Input: curl -X POST https://api.example.com/v1/users -H "Content-Type: application/json" -d '{"name":"Alice"}'

Output:

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpRequest.BodyPublishers;
import java.net.http.HttpResponse;
import java.util.Base64;

public class Main {
    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();

        HttpRequest.Builder builder = HttpRequest.newBuilder()
            .uri(URI.create("https://api.example.com/v1/users"))
            .header("Content-Type", "application/json")
            .method("POST", BodyPublishers.ofString("{\"name\":\"Alice\"}"));

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

        System.out.println(response.statusCode());
        System.out.println(response.body());
    }
}

Common errors

A -F/--form command produces a request built with BodyPublishers.noBody() and a comment listing the fields, not a working multipart request — HttpClient has no multipart body builder, and hand-rolling a boundary-delimited stream is exactly the kind of "reconstructed it wrong" bug this generator avoids by refusing to fabricate. If you need real multipart support, add OkHttp and use its MultipartBody instead.

Best practices

Check response.statusCode() before trusting the body — client.send(...) only throws on I/O failures (timeouts, connection resets), never on a 4xx/5xx HTTP status. For anything beyond a quick script, consider client.sendAsync(...) instead of the synchronous call shown here, so a slow endpoint doesn't block a calling thread you actually need.