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Create & validate digital certificates with PDF Generator API and Gmail

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Created by: Paolo Ronco || paoloronco
Paolo Ronco

Last update

Last update 19 days ago

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Quick overview

Issue and verify digital certificates with n8n using reusable PDF Generator API templates, unique certificate IDs, an n8n Data Table registry, Gmail delivery, and a public verification endpoint.

How it works

  1. Certificate creation — A POST webhook receives the candidate's name, surname, course, and email address.
  2. Unique ID validation — The workflow generates a Certification ID and checks the Data Table to prevent identifier collisions.
  3. Registry storage — Issued certificate records are persisted in an n8n Data Table for later lookup and verification.
  4. Template-based PDF generation — PDF Generator API receives JSON containing candidate, course, date, and ID values mapped to placeholders in a reusable visual template.
  5. Email delivery — Gmail sends the generated certificate PDF to the recipient supplied in the creation request.
  6. Public verification — The verification endpoint searches the registry by Certification ID and returns whether the certificate is valid and who it belongs to.

Setup

  1. Import the workflow — Import the included workflow JSON into n8n.
  2. Create the Data Table — Add Name, Surname, and CertificationID fields and configure the insert and lookup nodes.
  3. Import the PDF template — Import the provided PDF Generator API template and verify its placeholders match the JSON keys sent by the workflow.
  4. Configure PDF Generator API — Add credentials and select the imported template in the PDF generation node.
  5. Connect Gmail — Configure Gmail OAuth2 credentials for certificate delivery.
  6. Test and activate — Create a sample certificate, confirm PDF mapping and email delivery, then test verification before activation.

Requirements

  • n8n instance
  • n8n Data Table with Name, Surname, and CertificationID
  • PDF Generator API account and credentials
  • Imported PDF Generator API certificate template
  • Gmail OAuth2 credentials
  • Publicly reachable webhooks when exposed externally
  • Custom PDF Generator API template design (optional)
  • QR code or additional visual elements (optional)
  • Additional registry fields (optional)
  • Frontend, LMS, or portal consuming the verification endpoint (optional)

Customization

  • Template design — Change layout, fonts, colors, logos, signatures, QR codes, and other visual elements without embedding HTML in n8n.
  • Template variables — Extend the JSON payload and matching placeholders with additional certificate information.
  • Certificate ID — Replace the default ID-generation logic with another identifier format.
  • Email delivery — Customize Gmail subject, body, attachment name, and recipient logic.
  • Verification response — Extend the API response with additional non-sensitive certificate metadata.
  • External integrations — Connect certificate creation to forms, an LMS, CRM, e-commerce flow, or another application.

Additional info

The reusable PDF template is included under PDFgeneratorAPI-Template/.
Keep template placeholder names synchronized with the JSON keys sent by the workflow.
Review webhook exposure, personal-data handling, authentication, and abuse prevention before production use.