Claude API Webhook Retry Policy: A Practical Guide

If you're searching for a "Claude API webhook retry policy," the first thing to know is that Anthropic's Messages API doesn't send webhooks at all. It's a request/response API: you call it, it streams or returns a response, and that's the end of the transaction. There's no event push mechanism where Claude notifies your server when something happens.

What most people actually mean by this search is one of two things: (1) how does the Message Batches API handle status when you're waiting on large async jobs, since that feels webhook-adjacent, or (2) how do you design a retry policy for the webhooks your own service sends out after processing a Claude response. This guide covers both, because the retry logic you need depends heavily on which architecture you're building.

Claude's API is pull-based, not push-based

The core Messages API works two ways:

• Synchronous request/response — you send a request, you get a response back on the same connection.
• Streaming (SSE) — you get incremental chunks over an open connection until the response completes or the connection drops.

The Message Batches API is the closest thing to an async job system Anthropic offers, but it's still pull-based: you submit a batch, then poll a status endpoint until it reports ended. There is no callback URL parameter, no signed payload delivered to your infrastructure, and no built-in retry policy for a notification that doesn't exist. If a vendor or tutorial tells you to configure a "Claude webhook URL," that's not part of Anthropic's public API surface — you're either looking at a third-party wrapper or a misunderstanding of the batch polling flow.

This matters for retry policy because polling and webhooks fail in different ways. Polling failures are about backoff intervals and giving up on stale batches. Webhook failures are about delivery guarantees to a downstream consumer you control.

Retry policy for polling the Batch API

If you're using batches and treating status polling like a pseudo-webhook, keep the retry policy simple:

• Poll on an increasing interval (start at 5–10 seconds, back off to 60+ seconds for long-running batches) rather than hammering the endpoint every second.
• Treat 429 and 5xx responses from the status check itself as retryable with standard exponential backoff — this is separate from the batch's own processing state.
• Set a maximum polling window (e.g., 24 hours) and alert or fail the job rather than polling indefinitely.
• Cache the last known status so a transient polling failure doesn't reset your understanding of batch progress.

This isn't a retry policy for a webhook — it's a retry policy for a status check. Don't conflate the two when designing your system.

Building your own webhook layer on top of Claude

The real reason this search term exists is that a lot of teams build a service that calls Claude, then notifies other systems (a queue, a customer's endpoint, a Slack channel, another microservice) once a response is ready. That notification step is a real webhook, and it needs a real retry policy — one you design, since Anthropic isn't involved at that layer.

Here's a retry policy that works well in production for this pattern:

Retry schedule — exponential backoff with jitter, capped attempts:

Attempt 1: immediate
Attempt 2: 30s
Attempt 3: 2min
Attempt 4: 10min
Attempt 5: 30min
Attempt 6: 2hr (final attempt)

What counts as a failure worth retrying:

• Connection timeouts or DNS failures
• 5xx responses from the receiving endpoint
• 429 responses (respect a Retry-After header if present)

What should NOT be retried:

• 4xx responses other than 429 — these usually mean a malformed payload or auth problem that a retry won't fix
• Explicit 410 Gone from a consumer that's unsubscribed

Idempotency and ordering:

• Include a unique event_id in every payload so the receiver can deduplicate if a retry succeeds after a previous attempt actually landed but the ack was lost.
• Don't assume delivery order across retries — if event ordering matters, include a sequence number and let the consumer reorder.

Dead-lettering:

• After the final attempt fails, move the event to a dead-letter queue with the full payload and failure history, and expose it for manual replay. Silent drops are the most common cause of "why didn't my webhook fire" support tickets.

A minimal delivery function with backoff looks like this:

const delays = [0, 30_000, 120_000, 600_000, 1_800_000, 7_200_000];

async function deliverWebhook(url, payload, attempt = 0) {
  try {
    const res = await fetch(url, {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify(payload),
    });
    if (res.status === 429 || res.status >= 500) throw new Error(`retryable ${res.status}`);
    return res.status < 400;
  } catch (err) {
    if (attempt >= delays.length - 1) {
      await sendToDeadLetter(url, payload, err);
      return false;
    }
    await sleep(delays[attempt + 1]);
    return deliverWebhook(url, payload, attempt + 1);
  }
}

Where SubToAPI fits into this

If you're wrapping Claude access into an internal API that other teams or customer-facing apps call, you'll eventually need this webhook layer regardless of how you're calling the model. SubToAPI sits between your Claude subscription and your applications, giving you a stable HTTPS endpoint, streaming, tool use, and usage metadata per key — the metadata is useful here because you can correlate a specific Claude request with the downstream webhook event it triggered, which makes debugging delivery failures much easier than working from raw logs. See the docs or the quickstart if you're building this kind of layer and want the API side handled for you.

Getting started

If you're actually calling Claude directly and just need to know how errors and retries work at the request level (not the webhook level), that's a separate topic covered by standard exponential backoff practices for 429 and 5xx responses. This article is specifically about the notification layer you build around Claude, since Claude itself has no push mechanism to design a retry policy for.

Questions

Does Claude's API support webhooks for streaming responses? No. Streaming uses Server-Sent Events over a single open connection, not webhook callbacks. The connection stays open until the response finishes or errors.

How does the Message Batches API notify me when a batch is done? It doesn't push a notification — you poll the batch status endpoint until it reports ended, then retrieve results from the results URL provided in that response.

What retry policy should I use for webhooks I send after a Claude response completes? Exponential backoff with jitter over 5–6 attempts, retrying only on timeouts, 5xx, and 429 responses, with a dead-letter queue for anything that exhausts retries.