n8n Workflow: Issue Cohort Completion Certificates (PDFmill + Gmail + Drive)

Issue cohort completion certificates at scale—automatically—and archive them instantly

This n8n workflow issues personalized completion certificates for an entire cohort from a single validated webhook. It renders each PDF with pdfmill, sends it via Gmail, and archives the same certificate binary to Google Drive—then returns a clean issued count once both delivery steps succeed.

What this workflow does

• Receives one POST webhook containing the program, organization, issuer, completion date, and a complete attendees array.
• Validates every cohort and attendee field, including attendee names, a single mailbox address per recipient, positive hours, and an optional completion-date override—before any fan-out occurs.
• Prevents partial delivery: if the roster is empty or any field is malformed, it returns a single clear 400 response so no invalid cohort is partially emailed.
• Creates per-attendee items and assigns an execution-scoped certificate number that cannot overlap with adjacent n8n executions.
• Renders branded PDFs with pdfmill for each attendee and exposes the result in the data binary property.
• Delivers to Gmail and archives to Drive using the same PDF binary, waits for both branches, then returns the program, organization, and issued count.

Use cases

• Send completion certificates to graduating cohorts from a SaaS course platform webhook.
• Automate certificate issuance for bootcamps, training programs, or internal enablement programs.
• Centralize certificate archiving in Google Drive for audit-ready records.

Technical details

• Nodes / integrations: webhook, if, code, pdfmill, gmail, merge, Google Drive, plus supporting workflow notes (e.g., sticky note).
• Setup: install the verified pdfmill node; add pdfmill, Gmail, and Google Drive credentials; select the Drive folder to archive certificates.
• Webhook contract: the cohort-completed endpoint expects the documented program/organization/issuer/completion date and attendee fields.