n8n-nodes-webhookscheduler

This is an n8n community node for the Webhook Scheduler API.

Webhook Scheduler is a hosted API that sends an HTTP request at a future date and time you choose. It retries failed deliveries, keeps a log of every attempt, and lets you cancel a request before it is sent. This node covers the API: Schedule, Cancel, Cancel by Reference, Get and Get Many.

n8n is a fair-code licensed workflow automation platform.

• Installation
• Operations
• Credentials
• Use it as an AI Agent tool
• Example: a follow-up in 3 days, cancelled if the customer replies
• Errors
• Compatibility
• Resources

Installation

Follow the community nodes installation guide. The package name is n8n-nodes-webhookscheduler.

Operations

Resource: Job (a scheduled HTTP request).

Limits to know:

• Run At must be in the future. The Free plan schedules up to 7 days ahead and includes 100 deliveries a month. Paid plans schedule up to 365 days ahead.
• Reference: up to 120 characters, letters, digits and : . _ / - only. Use something like invoice-followup:in_1Q2w3E, not an email address.
• Body up to 100 KB, headers up to 16 KB. The URL must be public (private networks are rejected).
• Headers removed before delivery: Authorization, Proxy-*, Cookie, Set-Cookie, Content-Type, Content-Length, User-Agent, Host, Forwarded, X-Forwarded-For/Host/Proto, X-Real-IP, Via, Webhook-Signature, X-Webhook-Signature and hop-by-hop headers. To authenticate the call, send a secret in a custom header such as X-Api-Key, or verify the Webhook-Signature header on your receiver.

Credentials

1. Create a free account at webhookscheduler.com. No card needed.
2. Open Dashboard → API keys and create a key. Keys start with wh_live_ or wh_test_.
3. In n8n, create a Webhook Scheduler API credential and paste the key. The node only ever sends the key to https://webhookscheduler.com; the host cannot be changed.

The credential test calls GET /api/v1/jobs?limit=1, which needs a valid key and changes nothing.

Use it as an AI Agent tool

The node is marked usableAsTool, so an n8n AI Agent can call it.

1. Add an AI Agent node, then click + Tool and pick Webhook Scheduler.
2. Choose the operation, for example Schedule.
3. For each field the agent should decide, click the sparkle icon ("Let the model define this parameter") or write {{ $fromAI('runAt', 'ISO 8601 date-time in the future') }}.
4. Give the tool a plain description, for example "Schedules a follow-up for a customer. Use it when the user asks to be reminded or followed up later."

Self-hosted n8n: community nodes can only be used as tools when the instance sets N8N_COMMUNITY_PACKAGES_ALLOW_TOOL_USAGE=true.

Example: a follow-up in 3 days, cancelled if the customer replies

Give your AI Agent a "follow-up in 3 days" tool. The agent schedules the follow-up while it talks to the customer; a second workflow cancels it if the customer answers first.

Workflow 1: the agent and its tools

• AI Agent, with the system message: "When you promise to follow up, call schedule_follow_up with the customer ID. Never promise a follow-up without calling the tool."
• Tool: Webhook Scheduler → Schedule, renamed schedule_follow_up:
  • URL: the production URL of the Webhook trigger in workflow 3, for example https://your-n8n.example.com/webhook/follow-up-due
  • Run At: {{ $now.plus({ days: 3 }).toISO() }}
  • Body: {{ JSON.stringify({ customerId: $fromAI('customerId', 'The customer ID'), topic: $fromAI('topic', 'What to follow up on, in one sentence') }) }}
  • Additional Fields → Reference: follow-up:{{ $fromAI('customerId', 'The customer ID') }}
  • Additional Fields → Idempotency Key: follow-up:{{ $fromAI('customerId', 'The customer ID') }}:{{ $now.toFormat('yyyy-MM-dd') }} (one follow-up per customer per day, even if the agent calls the tool twice)

Workflow 2: the customer replied

• Trigger: your inbox or CRM ("new reply from customer").
• Webhook Scheduler → Cancel by Reference, Reference: follow-up:{{ $json.customerId }}.

Workflow 3: the follow-up is due

• Webhook trigger, path follow-up-due, method POST. Webhook Scheduler calls it after 3 days with the body you scheduled (customerId, topic).
• Check the customer's current state, then send the email or message.

Make the handler in workflow 3 idempotent: a delivery can be retried, and a cancel can arrive while the request is being sent.

Errors

The node turns API errors into messages you can act on:

Compatibility

Built with @n8n/node-cli 0.48.5 and n8n-workflow 2.x, declarative style, no runtime dependencies. Requires n8n 1.0 or later.

Resources

• Webhook Scheduler API reference
• n8n community nodes documentation

Version history

• 0.2.0: Cancel by Reference operation; the API key is only ever sent to https://webhookscheduler.com (no Base URL field); header help lists the headers the API removes; clear errors for 400, 401, 403, 404, 409 and 429; API-key link fixed.
• 0.1.0: Schedule, Cancel, Get and Get Many.