Automating SaaS Subscription Audits with the Notion API, Google Apps Script, and n8n

Description and use

Automating SaaS subscription audits with Notion API, Google Apps Script, and n8n automatically extracts invoice data from email, stores it in Notion, and evaluates cost per hour saved, saving time and money.

Problem

Freelancers and small projects often lose track of low‑cost SaaS and API subscriptions, leading to unnecessary spending.

Outcome

The setup automatically logs invoice emails into Notion, calculates cost per hour saved, and flags subscriptions for action, eliminating manual entry and reducing wasted spend.

Workflow

• Search Gmail threads matching "subject:(invoice OR receipt) newer_than:1d".
• Extract sender name, date, and dollar amount via regex.
• Send a POST request to https://api.notion.com/v1/pages to append the row to the Notion database.
• (Optional) Use n8n: Gmail Trigger → OpenAI Chat Model (extract vendor, amount, billing cycle as JSON) → Notion Node (create page) → Slack Node (notify on yearly renewal).

Evidence

One recurring issue when running small projects or freelancing is losing track of $10 to $49/mo SaaS and API subscriptions.

Source

To fix this without paying for another recurring SaaS tool, I put together a lightweight setup that logs invoice emails into a Notion database automatically and calculates whether each tool is worth keeping.

Source

Search Gmail threads matching subject:(invoice OR receipt) newer_than:1d.

Source

Send a POST request to https://api.notion.com/v1/pages to append the row directly to the Notion database.

Source