Klaviyo Webhooks Events

What it does

When your agent uses it

• Setting up webhook endpoints
• Handling Klaviyo event notifications
• Creating event-driven integrations with Klaviyo
• With phrases like klaviyo webhook

Example prompts

• “klaviyo webhook”
• “klaviyo events”
• “klaviyo webhook signature”
• “/klaviyo-webhooks-events”

Requirements

• A credential in KLAVIYO_WEBHOOK_SIGNING_SECRET
• Compatibility (from SKILL.md): Designed for Claude Code
• Pre-approved tools (allowed-tools): Read, Write, Edit, Bash(curl:*), Bash(npm:*)

Workflow steps

6 steps, taken from the first numbered list in SKILL.md.

1. 1Create a webhook subscription — call webhooksApi.createWebhook with the target endpointUrl and webhookTopics, then save the signing secret…
2. 2Verify the signature — recompute the HMAC-SHA256 over the raw request body and compare with a timing-safe check (skeleton below).
3. 3Receive events — mount an Express route with express.raw({ type: 'application/json' }) so the raw body survives for verification; reject…
4. 4Route by topic — dispatch event.type to a per-topic handler map (profile.created, campaign.sent, ...).
5. 5Deduplicate — record each processed event ID in Redis with a TTL so Klaviyo retries are short-circuited.
6. 6Manage subscriptions — list, inspect topics, and delete webhooks via the API.

What it can do on your machine

Read from SKILL.md and the folder at commit cfae287. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Write
  • Edit
  • Bash(curl:*)
  • Bash(npm:*)

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • npm
  • ngrok

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • developers.klaviyo.com

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names these keys or tokens, usually read from environment variables:

  • KLAVIYO_WEBHOOK_SIGNING_SECRET

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Designed for Claude Code

  From compatibility in the SKILL.md frontmatter.

Context cost

Klaviyo Webhooks Events loads about 1.6k tokens when it runs, and up to ~3.7k if it reads all its reference files. Until then it costs about 95 tokens; SKILL.md has 552 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~95

When it runs · the whole SKILL.md, loaded when a task matches

~1.6k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~3.7k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from jeremylongshore/tons-of-skills-marketplace at commit cfae287, republished under its MIT licence (© jeremylongshore). 552 words, ~1,626 tokens.

name

klaviyo-webhooks-events

description

Implement Klaviyo webhooks with HMAC-SHA256 signature verification and event handling. Use when setting up webhook endpoints, handling Klaviyo event notifications, or creating event-driven integrations with Klaviyo. Trigger with phrases like "klaviyo webhook", "klaviyo events", "klaviyo webhook signature", "handle klaviyo events", "klaviyo notifications".

allowed-tools

Read, Write, Edit, Bash(curl:*), Bash(npm:*)

compatibility

Designed for Claude Code

version

1.7.0

license

MIT

author

Jeremy Longshore <jeremy@intentsolutions.io>

tags

saas, klaviyo, email-marketing, cdp

// src/klaviyo/webhook-verify.ts
import crypto from 'crypto';

export function verifyWebhookSignature(
  rawBody: Buffer | string,
  signature: string,
  secret: string
): boolean {
  if (!signature || !secret) return false;

  const expectedSignature = crypto
    .createHmac('sha256', secret)
    .update(typeof rawBody === 'string' ? rawBody : rawBody.toString())
    .digest('base64');

  try {
    return crypto.timingSafeEqual(
      Buffer.from(signature),
      Buffer.from(expectedSignature)
    );
  } catch {
    return false;
  }
}

npm run dev              # start your app on localhost:3000
ngrok http 3000          # expose it publicly
# register the ngrok URL as the webhook endpoint in Klaviyo,
# trigger an event, and watch your logs

© jeremylongshore, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files (references) in skills/.curated/klaviyo-webhooks-events of jeremylongshore/tons-of-skills-marketplace.

• SKILL.md
• references/examples.md
• references/implementation.md

Open the folder on GitHubat commit cfae287