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Guide

How to receive webhooks in Java minimal receiver → production-ready processing

Start with a minimal “native” receiver, but don’t stop there. In production, reliable webhook handling means verification, retries, idempotency, and backpressure — which is where Hooque simplifies everything.

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Building for a specific provider? Browse provider webhook APIs.

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TL;DR

  • Treat “receive webhooks in Java” as an ops problem, not just a route handler.
  • Verify the request before parsing/side effects (use a verifySignature(...) stub, then implement provider verification).
  • Return 2xx quickly; move work to a worker/queue to avoid timeouts and retries.
  • Assume retries and design idempotency (dedupe by event id + unique constraints).
  • Log + store raw payloads for replayable debugging.
  • If you need one workflow across many providers, centralize ingest + standardize consumption.

Deep dives: security, retries, queue migration.

Anti-patterns

  • Doing business logic inline in the Java request handler.
  • Parsing/transforming the body before verification (breaks signing inputs).
  • Returning 2xx before authenticity is proven.
  • Skipping idempotency (retries become double side effects).

If you’re triaging a live incident, use the debugging playbook .

Table of contents

  1. Why it's hard
  2. Minimal receiver
  3. With Hooque
  4. REST loop
  5. SSE loop
  6. FAQ

Framework shortcuts

If you’re already using a framework, jump straight to the minimal framework receiver, then reuse the same production guidance and Hooque consumer loops.

  1. Spring Boot
    How to receive webhooks in Spring Boot
  2. Micronaut
    How to receive webhooks in Micronaut
  3. Quarkus
    How to receive webhooks in Quarkus

Why it's hard in production

A route handler is the easy part. Supporting multiple senders means multiple security models, spikes, and retry semantics.

Verify authenticity + stop replays

Use a verifySignature(...) stub here, then implement real verification + replay defense for each provider.

Read the guide

Assume retries (duplicates are optional)

Treat every delivery as at-least-once and make side effects idempotent (DB constraints, dedupe keys).

Read the guide

Don’t do work in the request path

Ack fast, process async. Otherwise timeouts, deploys, and spikes turn into missed webhooks.

Read the guide

Debug with real payloads

Save the exact body + headers so you can replay deterministically after a fix.

Read the guide

Add monitoring + alerts early

Track delivered vs rejected, processing latency, queue depth, and error rates.

Read the guide

Iterate locally without losing events

Tunnels help, but durable capture + replay removes the “my laptop was asleep” problem.

Read the guide

Minimal standard-library receiver (Java)

This is a minimal starting point. Keep verifySignature(...) as a stub here, then implement provider-specific verification and replay defense in the security guide . 

// Java 11+ (com.sun.net.httpserver.HttpServer)
// Run: javac WebhookServer.java && java WebhookServer
import com.sun.net.httpserver.HttpServer;
import java.io.IOException;
import java.io.InputStream;
import java.net.InetSocketAddress;
import java.nio.charset.StandardCharsets;

public class WebhookServer {
  private static void verifySignature(com.sun.net.httpserver.Headers headers, byte[] body) {
    // don't compromise on security
    // TODO: implement provider-specific signature verification
  }

  private static void processData(byte[] body) {
    // TODO: your business logic (DB writes, external API calls, etc.)
  }

  public static void main(String[] args) throws Exception {
    HttpServer server = HttpServer.create(new InetSocketAddress(3000), 0);
    server.createContext("/webhooks", exchange -> {
      if (!exchange.getRequestMethod().equalsIgnoreCase("POST")) {
        exchange.sendResponseHeaders(405, -1);
        return;
      }
      
      byte[] body;
      try (InputStream is = exchange.getRequestBody()) {
        body = is.readAllBytes();
      } catch (IOException e) {
        exchange.sendResponseHeaders(400, -1);
        return;
      }
      
      verifySignature(exchange.getRequestHeaders(), body);

      // What happens if it fails or times out?
      // Most providers retry -> duplicates unless you designed idempotency.
      processData(body);

      // IMPORTANT: ack fast to avoid timeouts and duplicate deliveries.
      byte[] ok = "ok".getBytes(StandardCharsets.UTF_8);
      exchange.sendResponseHeaders(200, ok.length);
      exchange.getResponseBody().write(ok);
      exchange.close();
      System.out.println("received webhook bytes=" + body.length);
    });
    server.start();
    System.out.println("listening on http://localhost:3000/webhooks");
  }
}

Hooque turns any webhook into a reliable queue.

Jump to REST Jump to SSE

Non-obvious scenario: you can’t expose a port

In real deployments, the hardest part is often “where does this endpoint run?” (NAT, corporate networks, locked-down environments, short-lived preview deployments). Hooque decouples inbound receiving from processing so your Java app doesn’t need to be the public receiver.

The easy path: receive with Hooque + consume forever

Hooque turns inbound webhooks into a durable queue. Your code becomes a run-forever worker that pulls or streams events and acks/nacks/rejects explicitly.

  • No need to run a public webhook endpoint in every environment (especially for local dev).
  • Durable capture + replay/inspection so “we missed the webhook” becomes debuggable.
  • Explicit Ack / Nack / Reject lifecycle so retries are under your control.
  • Backpressure and spike absorption: buffer now, process at your pace.
  • One consumption pattern across many senders (even if their security/retry rules differ).

Flow

  1. Provider delivers → Hooque ingest endpoint
  2. Hooque persists payload immediately
  3. Your worker pulls (REST) or streams (SSE)
  4. Your worker ack/nack/rejects explicitly

Next steps

Hooque REST polling loop (runs forever)

Polling is a good default when you want a simple worker loop. It also works in environments where long-lived connections are unreliable. 

// Java 11+ (HttpClient)
// Runs forever: poll /next, ack/nack/reject explicitly.
import java.net.URI;
import java.net.http.*;
import java.time.Duration;
import java.util.*;
import java.util.regex.*;

public class HooquePoller {
  static class Msg {
    String payload;
    Map<String, Object> meta;
    Msg(String p, Map<String, Object> m) { this.payload = p; this.meta = m; }
  }

  public static void main(String[] args) throws Exception {
    String nextUrl = System.getenv().getOrDefault("HOOQUE_QUEUE_NEXT_URL", "https://app.hooque.io/queues/<consumerId>/next");
    String token = System.getenv().getOrDefault("HOOQUE_TOKEN", "hq_tok_replace_me");
    HttpClient client = HttpClient.newBuilder().connectTimeout(Duration.ofSeconds(10)).build();

    while (true) {
      Msg msg = getNextMessage(client, nextUrl, token);
      if (msg == null) {
        Thread.sleep(1000);
        continue;
      }

      try {
        processData(msg.payload, msg.meta);
        ack(client, msg, token);
      } catch (Exception err) {
        nack(client, msg, token, err);
      }
    }
  }

  private static Msg getNextMessage(HttpClient client, String nextUrl, String token) {
    try {
      HttpRequest req = HttpRequest.newBuilder(URI.create(nextUrl))
        .header("Authorization", "Bearer " + token)
        .timeout(Duration.ofSeconds(30))
        .GET()
        .build();

      HttpResponse<String> resp = client.send(req, HttpResponse.BodyHandlers.ofString());
      if (resp.statusCode() == 204) return null;
      if (resp.statusCode() >= 400) {
        System.out.println("next() failed: " + resp.statusCode() + " " + resp.body());
        Thread.sleep(2000);
        return null;
      }

      String metaRaw = resp.headers().firstValue("X-Hooque-Meta").orElse("{}");
      Map<String, Object> meta = new HashMap<>();
      meta.put("ackUrl", jsonField(metaRaw, "ackUrl"));
      meta.put("nackUrl", jsonField(metaRaw, "nackUrl"));
      meta.put("rejectUrl", jsonField(metaRaw, "rejectUrl"));
      meta.put("messageId", jsonField(metaRaw, "messageId"));

      return new Msg(resp.body(), meta);
    } catch (Exception e) {
      System.out.println("Worker connection err: " + e.getMessage());
      try { Thread.sleep(2000); } catch (InterruptedException ignore) {}
      return null;
    }
  }

  private static void processData(String payload, Map<String, Object> meta) throws Exception {
    // Example real-life task: run a script on webhook events.
    // new ProcessBuilder("./on_webhook.sh").inheritIO().start().waitFor();
    System.out.println("event: " + meta.get("messageId"));
  }

  private static void ack(HttpClient client, Msg msg, String token) throws Exception {
    String url = (String) msg.meta.get("ackUrl");
    if (url != null) post(client, url, token, null);
  }

  private static void nack(HttpClient client, Msg msg, String token, Exception err) {
    try {
      String nackUrl = (String) msg.meta.get("nackUrl");
      String rejectUrl = (String) msg.meta.get("rejectUrl");
      String url = nackUrl != null ? nackUrl : rejectUrl;
      if (url != null) {
        post(client, url, token, "{\"reason\":\"" + jsonEscape(err.getMessage()) + "\"}");
      }
    } catch (Exception ignored) {}
  }

  private static String jsonField(String json, String key) {
    Pattern p = Pattern.compile("\"" + Pattern.quote(key) + "\"\\s*:\\s*\"([^\"]+)\"");
    Matcher m = p.matcher(json == null ? "" : json);
    return m.find() ? m.group(1) : null;
  }

  private static String jsonEscape(String s) {
    if (s == null) return "";
    return s.replace("\\", "\\\\").replace("\"", "\\\"");
  }

  private static void post(HttpClient client, String url, String token, String jsonBody) throws Exception {
    HttpRequest.Builder b = HttpRequest.newBuilder(URI.create(url))
      .header("Authorization", "Bearer " + token)
      .timeout(Duration.ofSeconds(30));
    if (jsonBody != null) b.header("Content-Type", "application/json");
    HttpRequest req = (jsonBody == null)
      ? b.POST(HttpRequest.BodyPublishers.noBody()).build()
      : b.POST(HttpRequest.BodyPublishers.ofString(jsonBody)).build();
    client.send(req, HttpResponse.BodyHandlers.discarding());
  }
}

Hooque SSE stream consumer (runs forever)

SSE is great for low-latency processing: keep a connection open, process events as they arrive, and reconnect on disconnects. 

// Java 11+ — SSE consumer (HttpClient)
// Runs forever: connect to /stream, handle "message" events, ack/nack/reject explicitly.
import java.io.*;
import java.net.URI;
import java.net.http.*;
import java.time.Duration;
import java.util.*;
import java.util.regex.*;
import java.util.function.Consumer;

public class HooqueSse {
  static class Msg {
    String payload;
    Map<String, Object> meta;
    Msg(String p, Map<String, Object> m) { this.payload = p; this.meta = m; }
  }

  public static void main(String[] args) throws Exception {
    String streamUrl = System.getenv().getOrDefault("HOOQUE_QUEUE_STREAM_URL", "https://app.hooque.io/queues/<consumerId>/stream");
    String token = System.getenv().getOrDefault("HOOQUE_TOKEN", "hq_tok_replace_me");
    HttpClient client = HttpClient.newHttpClient();

    while (true) {
      try {
        getMessageStream(client, streamUrl, token, msg -> {
          try {
            processData(msg.payload, msg.meta);
            ack(client, msg, token);
          } catch (Exception err) {
            nack(client, msg, token, err);
          }
        });
      } catch (Exception e) {
        System.out.println("stream error: " + e.getMessage());
        Thread.sleep(2000);
      }
    }
  }

  private static void getMessageStream(HttpClient client, String streamUrl, String token, Consumer<Msg> onMessage) throws Exception {
    HttpRequest req = HttpRequest.newBuilder(URI.create(streamUrl))
      .header("Authorization", "Bearer " + token)
      .header("Accept", "text/event-stream")
      .timeout(Duration.ofSeconds(0))
      .GET()
      .build();

    HttpResponse<InputStream> resp = client.send(req, HttpResponse.BodyHandlers.ofInputStream());
    if (resp.statusCode() >= 400) throw new RuntimeException("stream failed: " + resp.statusCode());

    try (BufferedReader br = new BufferedReader(new InputStreamReader(resp.body()))) {
      String event = null;
      StringBuilder data = new StringBuilder();
      String line;

      while ((line = br.readLine()) != null) {
        if (line.startsWith(":")) continue;
        if (line.isEmpty()) {
          if ("message".equals(event) && data.length() > 0) {
            Map<String, Object> meta = new HashMap<>();
            String rawData = data.toString();
            String metaRaw = jsonFieldRaw(rawData, "meta");
            
            meta.put("ackUrl", jsonField(metaRaw, "ackUrl"));
            meta.put("nackUrl", jsonField(metaRaw, "nackUrl"));
            meta.put("rejectUrl", jsonField(metaRaw, "rejectUrl"));
            meta.put("messageId", jsonField(metaRaw, "messageId"));

            onMessage.accept(new Msg(rawData, meta));
          }
          event = null;
          data.setLength(0);
          continue;
        }
        if (line.startsWith("event:")) event = line.substring(6).trim();
        if (line.startsWith("data:")) {
          if (data.length() > 0) data.append("\n");
          data.append(line.substring(5).trim());
        }
      }
    }
  }

  private static void processData(String payload, Map<String, Object> meta) throws Exception {
    System.out.println("event: " + meta.get("messageId"));
  }

  private static void ack(HttpClient client, Msg msg, String token) {
    try {
      String url = (String) msg.meta.get("ackUrl");
      if (url != null) post(client, url, token, null);
    } catch (Exception e) {}
  }

  private static void nack(HttpClient client, Msg msg, String token, Exception err) {
    try {
      String nackUrl = (String) msg.meta.get("nackUrl");
      String rejectUrl = (String) msg.meta.get("rejectUrl");
      String url = nackUrl != null ? nackUrl : rejectUrl;
      if (url != null) {
        post(client, url, token, "{\"reason\":\"" + jsonEscape(err.getMessage()) + "\"}");
      }
    } catch (Exception e) {}
  }

  private static String jsonFieldRaw(String json, String key) {
    Pattern p = Pattern.compile("\"" + Pattern.quote(key) + "\"\\s*:\\s*(\\{.*?\\})");
    Matcher m = p.matcher(json == null ? "" : json);
    return m.find() ? m.group(1) : "{}";
  }

  private static String jsonField(String json, String key) {
    Pattern p = Pattern.compile("\"" + Pattern.quote(key) + "\"\\s*:\\s*\"([^\"]+)\"");
    Matcher m = p.matcher(json == null ? "" : json);
    return m.find() ? m.group(1) : null;
  }

  private static String jsonEscape(String s) {
    if (s == null) return "";
    return s.replace("\\", "\\\\").replace("\"", "\\\"");
  }

  private static void post(HttpClient client, String url, String token, String jsonBody) throws Exception {
    HttpRequest.Builder b = HttpRequest.newBuilder(URI.create(url))
      .header("Authorization", "Bearer " + token);
    if (jsonBody != null) b.header("Content-Type", "application/json");
    HttpRequest req = (jsonBody == null)
      ? b.POST(HttpRequest.BodyPublishers.noBody()).build()
      : b.POST(HttpRequest.BodyPublishers.ofString(jsonBody)).build();
    client.send(req, HttpResponse.BodyHandlers.discarding());
  }
}

FAQ

Quick answers for the questions that come up right before you ship.

What status code should I return for webhooks in Java?

General: Usually return a fast 2xx after validating authenticity and basic schema. Timeouts and 5xx commonly trigger retries.

How Hooque helps: Hooque acknowledges ingest immediately and persists the payload. Your worker acks/nacks/rejects explicitly after processing.

Do I need signature verification in Java?

General: Yes, unless the sender is fully trusted and on a private network. A public endpoint without verification is easy to forge and easy to replay.

How Hooque helps: Hooque can verify at ingest for supported providers or using generic strategies. Either way, your worker receives a normalized meta object and can stay focused on processing.

Why do I see duplicate webhook events in Java?

General: Retries are normal: timeouts, transient network failures, and 5xx responses all produce duplicates. Design idempotency around event ids and side-effect boundaries.

How Hooque helps: Hooque makes delivery outcomes explicit (ack/nack/reject) and provides replay/inspection so you can fix issues without guessing what was received.

How do I test webhooks locally in Java?

General: You can use a tunnel, but local dev still breaks on sleep, VPNs, clock skew, and signature-byte mismatches.

How Hooque helps: With Hooque you can avoid inbound locally: receive events into a durable queue and pull/stream to your laptop, then replay from the UI after changes.

Should I use REST polling or SSE streaming for webhook processing?

General: Use REST polling for simple batch workers and environments without long-lived connections. Use SSE for low-latency “process as it arrives” flows.

How Hooque helps: Hooque supports both: `GET /next` for polling and `GET /stream` for streaming. Both include meta with ready-to-call ack/nack/reject URLs.

Start processing webhooks reliably

Create a webhook endpoint, receive events, then run your worker forever using REST polling or SSE streaming — with explicit ack/nack/reject control.

Start for free See pricing

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