n8n Workflow: SSL/TLS Cert Expiry Monitor via HTTP API

Stay ahead of expiring SSL/TLS certificates with an automated n8n HTTP API monitor

This n8n workflow checks your SSL/TLS certificate inventory over an HTTP API, calculates how many days remain until each certificate expires, and automatically prepares renewal reminders for Watch/Warning items and critical alerts for Critical expirations.

What this workflow does

• Runs daily at 06:00 (or can be started manually for testing).
• Sets the certificate inventory API URL and configurable expiry thresholds: watch, warning, and critical (days until expiry).
• Calls the certificate inventory HTTP API using an HTTP header authentication credential to retrieve certificates in scope, then waits briefly before processing.
• Splits the inventory into one item per certificate and calculates days until expiry, assigning an urgency tier: OK, Watch, Warning, or Critical.
• Drops certificates in OK tier (no action taken).
• Marks Watch and Warning certificates as ready for a standard renewal reminder payload.
• Applies a short `dedup` window for Critical certificates, then prepares them as an urgent renewal task/alert payload after the delay.

Use cases

• SaaS operators who want predictable SSL/TLS renewal follow-ups without manual spreadsheet checks.
• Automation engineers monitoring multiple environments where certificate lifecycles vary by service.
• Teams integrating a custom certificate inventory service via HTTP and needing urgency-based renewal dispatching.

Technical details

• Nodes/tech stack: set, wait, switch, split out, sticky note, HTTP request
• Integration: HTTP API for SSL/TLS certificate inventory (with HTTP Header Auth)
• Configuration: base URL, scope/query parameters, watchDaysThreshold, warningDaysThreshold, criticalDaysThreshold, and includeInternalServices