Resend Java SDK

Installation

To install the Java SDK, add the following dependency to your project:

Gradle

implementation 'com.resend:resend-java:+'

Maven

<dependency>
    <groupId>com.resend</groupId>
    <artifactId>resend-java</artifactId>
    <version>LATEST</version>
</dependency>

Setup

First, you need to get an API key, which is available in the Resend Dashboard.

Example

package com.resend;

import com.resend.services.emails.model.*;
import com.resend.core.provider.AuthenticationProvider;
import com.resend.core.provider.impl.AuthenticationProviderStandard;
import com.resend.services.emails.ResendEmails;

public class Main {
    public static void main(String[] args) {
        Resend resend = new Resend("re_123");

        CreateEmailOptions params = CreateEmailOptions.builder()
                .from("Me <me@exemple.io>")
                .to("to@example", "you@example.com")
                .cc("carbon@example.com", "copy@example.com")
                .bcc("blind@example.com", "carbon.copy@example.com")
                .replyTo("reply@example.com", "to@example.com")
                .text("Hello, world!")
                .subject("Hello from Java!")
                .build();

        try {
            CreateEmailResponse data = resend.emails().send(params);
            System.out.println(data.getId());
        } catch (ResendException e) {
            e.printStackTrace();
        }
    }
}

Configuration

new Resend("re_123") uses sensible defaults. Use Resend.builder() to set a proxy, timeouts or a custom base URL:

import com.resend.Resend;
import java.net.InetSocketAddress;
import java.net.Proxy;
import java.time.Duration;

// 1. Configure the proxy server
Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("your.proxy.host", 8080));

// 2. Add the proxy and any other options to the builder, then build the client
Resend resend = Resend.builder()
    .apiKey("re_123")
    .proxy(proxy)
    .connectTimeout(Duration.ofSeconds(5))
    .readTimeout(Duration.ofSeconds(30))
    .build();

Create one Resend instance and reuse it: every service it returns shares the same HTTP client.

Custom HTTP client

To take full control of the HTTP layer, pass your own IHttpClient with .httpClient(...). For example, to use your own OkHttpClient (interceptors, TLS settings, a shared connection pool), add the com.squareup.okhttp3:okhttp-jvm dependency to your build and wrap it in the built-in HttpClient:

import com.resend.Resend;
import com.resend.core.net.impl.HttpClient;
import okhttp3.OkHttpClient;

// 1. Configure your OkHttpClient, e.g. with an interceptor that logs every request
OkHttpClient okHttpClient = new OkHttpClient.Builder()
    .addInterceptor(chain -> {
        System.out.println(chain.request().method() + " " + chain.request().url());
        return chain.proceed(chain.request());
    })
    .build();

// 2. Wrap it in the built-in HttpClient and build the client
Resend resend = Resend.builder()
    .apiKey("re_123")
    .httpClient(new HttpClient(okHttpClient, "https://api.resend.com"))
    .build();

A custom httpClient can't be combined with baseUrl, the timeouts or proxy; configure those on your client.

You can view all the examples in the examples folder