Claude webhooks that survive a Claude follow-up.

The timing problem

One URL change — the Claude pipeline stays the same

AnyHook acks Anthropic instantly, then delivers the verified event to your endpoint with the original Anthropic-Signature plus a re-signed AnyHook-Signature.

// In your Anthropic dashboard, set the webhook URL to:
//    https://in.anyhook.net/{user-slug}/{app-slug}
//
// Your handler is now free to run a follow-up Claude call.

import Anthropic from "@anthropic-ai/sdk";
import { verifyWebhook } from "@anyhook/verify";

const anthropic = new Anthropic();

export async function POST(req: Request) {
  if (!(await verifyWebhook(req, process.env.ANYHOOK_SIGNING_SECRET!))) {
    return new Response("invalid", { status: 401 });
  }

  const { agent_result } = await req.json();

  // Free to take 30+ seconds. Anthropic already saw 200.
  const summary = await anthropic.messages.create({
    model: "claude-opus-4-7",
    max_tokens: 800,
    messages: [{ role: "user", content: `Summarise: ${agent_result}` }],
  });

  await persistSummary(summary);
  return new Response("ok", { status: 200 });
}

Questions teams ask

How does AnyHook verify Anthropic's signature?

AnyHook does HMAC-SHA256 verification against the source_secret you configure for the destination, before accepting the event. The original anthropic-signature header is forwarded intact, and AnyHook adds its own AnyHook-Signature for downstream verification.

Will Claude Managed Agent webhooks count toward my Anthropic limits?

Anthropic delivers each event once to AnyHook (with their normal retry policy if AnyHook itself failed to ack). After that, AnyHook handles all downstream retries to your endpoint. Your handler being slow does not pressure Anthropic.

Can I see the raw Claude payload after the fact?

Yes. AnyHook stores every event (encrypted at rest) for 3 / 30 / 90 days depending on plan. You can inspect the original payload, replay it to your endpoint, or fork it to a second destination.