Finance & Accounting medium to set up

Audit SaaS Subscription Waste

Monthly audit scans Gmail for billing emails, extracts vendor details via GPT-4.1-mini, updates a Google Sheet.

Verified 2026-07-07

Founder-ExecOps-IT

What it does

You automatically scan your Gmail for billing emails to identify subscription costs and renewal dates without manual tracking. The agent extracts vendor details, calculates annualized spending, and updates a Google Sheet while emailing you a summary of total waste to help you cut unnecessary expenses.

How it works

When it runs: On a schedule · Scheduled · monthly
How hands-off: Assists you, you do the final step
Setup: An afternoon · about an afternoon
Works with: Gmail, OpenAI Chat Model, Google Sheets, Code

Tools that fit

Services

Gmail : Search billing emails and send digest report

Google Sheets : Store vendor data and upsert results

LLM

OpenAI Chat Model : Extract subscription details and classify spend

api

Code : Clean JSON and calculate annualized costs

Watch out for

Currency symbols vary across providers so parse amounts as strings first then convert to a float for accurate summation.
LLMs may hallucinate renewal dates if they are not explicitly stated in the email text, add a fallback rule to use the current month end date.
Gmail API has strict rate limits on search queries so batch requests or add delays between scanning different keyword sets.
Duplicate emails can cause redundant rows in Sheets so ensure the upsert logic checks for existing vendor records before inserting.

Seen in the wild

n8n: Audit SaaS subscription waste from Gmail with GPT-4.1-mini and Google Sheet template

Want this running in your business?

This is what I do. I design and build AI agents like this one, and keep them running. If you want it set up for your team instead of doing it yourself, get in touch.

Get in touch

Who it's for

Built for founders and execs who need finance & accounting handled without hiring for it.

Ops-IT teams triaging their own internal requests get the same pattern, different queue.

Frequently asked questions

Who is this for?

founders and execs and ops and IT teams, or anyone doing finance & accounting work who wants this handled automatically rather than manually.

How long does it take to set up?

An afternoon: plan for about an afternoon to get it running end to end.

Related use cases

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