Create and Send Pennylane Invoices from Webhook Data

Overview

This workflow provides a secure, production-ready webhook endpoint that automatically creates finalized invoices in Pennylane and optionally sends them by email to the customer. It is designed for SMEs, freelancers, and any business using Pennylane who want to automate invoice creation from external systems such as CRMs, web forms, or custom applications.

By exposing a single POST endpoint with Basic HTTP authentication, the workflow validates the incoming payload, looks up or creates the customer in Pennylane, constructs an invoice with line items, VAT, and due date, finalizes it (non-draft), and—if requested—emails it to the customer with automatic retry logic. The webhook always returns a structured JSON response with invoice details and email delivery status.

Workflow Steps

1. WH Receive Invoice Data (Webhook node) — Accepts POST requests at path /pennylane-invoice. Authentication: HTTP Basic Auth (user must provide a credential with username and password). Validates that incoming data is well-formed.
2. Code Validate Payload (Code node) — Runs JavaScript to validate required fields (customer_name, customer_email, items[] with label, quantity, unit_price). It applies sensible defaults (country: FR, currency: EUR, VAT rate: FR_200, due date: +30 days) and throws an error if validation fails.
3. PL Search Customer (HTTP Request node) — Makes a GET request to Pennylane API GET /api/external/v2/customers with a query filter by email. Authentication: HTTP Header Auth (Bearer token). Looks for an existing customer by email.
4. IF Customer Exists (IF node) — Checks if the search returned any customer records. If yes (output 0), goes to Set Customer ID; if no (output 1), goes to PL Create Customer.
5. PL Create Customer (HTTP Request node) — POST to POST /api/external/v2/company_customers with customer name, email, and billing address. Auth: HTTP Header Auth.
6. Set Customer ID (Set node) — Sets customer_id from either the existing customer ID (from search) or the newly created customer ID. Uses expression {{ $json.id ?? $json.items?.[0]?.id }}.
7. Code Build Invoice Payload (Code node) — Builds the invoice payload object using customer ID, line items, dates, and VAT rates. Converts unit_price to a formatted string (e.g., "1500.00").
8. PL Create Invoice (HTTP Request node) — POST to POST /api/external/v2/customer_invoices with the constructed payload. Auth: HTTP Header Auth. Creates a finalized invoice (draft: false).
9. IF Send Email (IF node) — Checks the send_email boolean from the original payload. If true, proceeds to email sending path; if false, goes directly to Set Output Response.
10. Set Email Attempt (Set node) — Increments an attempt counter for email retry logic.
11. Wait PDF Generation (Wait node) — Pauses for 1 minute to allow Pennylane to generate the PDF of the invoice.
12. PL Send Invoice Email (HTTP Request node) — POST to POST /api/external/v2/customer_invoices/{id}/send_by_email. Auth: HTTP Header Auth. Configured with neverError: true to capture full response and avoid throwing.
13. IF Email Sent (IF node) — Checks if the HTTP status code is 204 (success). If yes, goes to Set Output Response; if no (e.g., 409 conflict), goes to Code Evaluate Email Retry.
14. Code Evaluate Email Retry (Code node) — Evaluates whether the email should be retried (409 status and attempt count < 5). Returns a retry boolean.
15. IF Can Retry Email (IF node) — If retry is true, loops back to Set Email Attempt and repeats the wait/send cycle. If false, goes to Set Email Delivery Failed.
16. Set Email Delivery Failed (Set node) — Constructs a response object indicating invoice creation succeeded but email delivery did not (with status code and message).
17. Set Output Response (Set node) — Final node that assembles the webhook response JSON with success, invoice_id, invoice_number, amount, customer, public_url, and email_sent.

Setup Instructions

1. Pennylane API Token: Log in to your Pennylane account, go to Settings > API Tokens, and create a token with at least customer_invoices:all and customers:all scopes. Copy the token.
2. n8n Credentials:
   • Create an HTTP Basic Auth credential for the webhook. Use any username/password you like—this protects your endpoint.
   • Create an HTTP Header Auth credential for Pennylane. Set the header name to Authorization and the value to Bearer <YOUR_PENNYLANE_TOKEN>.
3. Configure the Webhook: In the WH Receive Invoice Data node, select your Basic Auth credential. The production webhook URL will be shown when the workflow is activated.
4. Set Invoice Numbering: Ensure sequential invoice numbering is enabled in your Pennylane settings.
5. Test Without Email: Send a test payload with "send_email": false to verify invoice creation before enabling customer email delivery.
6. Activate: Publish the workflow and use the provided webhook URL in your external system.

Use Cases & Variations

• CRM Integration: Trigger this workflow from a CRM (e.g., HubSpot, Salesforce) when a deal is won to automatically generate and send an invoice.
• Form Submission: Use a web form tool like Typeform or Gravity Forms to collect invoice data and POST it to this endpoint.
• Custom Automation: Replace the webhook trigger with a schedule or a database listener to batch-create invoices.
• Multi-currency: Modify the payload to accept different currencies by changing the currency default.
• Draft Mode: Set draft: true in the invoice payload to create drafts for manual review before sending.
• Error Handling: Configure an n8n Error Workflow to capture and notify on any exceptions.

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        "content": "# Create and send Pennylane invoices from webhook data\n\n## Who is this for\n\nSMEs and freelancers using Pennylane who want to create invoices automatically from a CRM, form, or business application.\n\n## What it does\n\nA protected POST webhook validates customer and line-item data, finds or creates the customer in Pennylane, creates a finalized invoice, optionally emails it through Pennylane, and returns the invoice details to the caller.\n\n## Security and setup\n\n1. Create an **HTTP Basic Auth** credential and select it on `WH Receive Invoice Data`. Never expose an unauthenticated invoicing webhook.\n2. Create an **HTTP Header Auth** credential for Pennylane: name `Authorization`, value `Bearer <YOUR_PENNYLANE_TOKEN>`.\n3. Select that Pennylane credential on all four `PL` HTTP Request nodes.\n4. Configure sequential invoice numbering in Pennylane.\n5. Test with `send_email: false` before enabling customer delivery. Email delivery retries Pennylane HTTP 409 responses once per minute, up to five attempts.\n6. Activate the workflow and use its production webhook URL.\n\nRequires n8n 1.40+ and a Pennylane API token with `customer_invoices:all` and `customers:all` scopes. Import verified with n8n 2.31.5.\n\nSource and full payload documentation: https://github.com/Gauthier-Huguenin/n8n-pennylane-auto-invoicing\n\nAdapted from the original template © 2026 Gauthier Huguenin. Distributed under the MIT License; the complete notice is included in this workflow.\n\n---\n\n### Flow\n\n`WH Receive Invoice Data`\n  → `Code Validate Payload`\n  → `PL Search Customer`\n  → `IF Customer Exists`\n    → yes: `Set Customer ID`\n    → no: `PL Create Customer` → `Set Customer ID`\n  → `Code Build Invoice Payload`\n  → `PL Create Invoice`\n  → `IF Send Email`\n    → yes: retry `Wait PDF Generation` → `PL Send Invoice Email` up to five times on HTTP 409\n    → no: `Set Output Response`\n  → `Set Output Response`",
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