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 to decide whether to keep, downgrade, or cancel subscriptions.

Problem

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

Outcome

Automated ingestion of invoice emails into Notion reduces manual effort, provides real‑time cost analysis, and helps users decide whether to keep, downgrade, or cancel subscriptions.

Workflow

• Search Gmail for invoice/receipt emails newer than one day
• Extract sender, date, and dollar amount via regex
• POST the extracted data to Notion API to create a page in the database
• Use Notion formulas to calculate monthly equivalent cost and cost per hour saved
• Flag each subscription as Keep, Downgrade, or Cancel based on cost per hour saved

Evidence

Instead of paying for Zapier just to parse receipt emails, you can run a 40-line Google Apps Script on a daily time trigger inside your Google account:

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

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

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From there, a simple conditional formula flags each row as Keep, Downgrade, or Cancel (Unused).

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