Gmail payment rails audit written to a Google Sheet

Gmail payment rails audit written to a Google Sheet

An n8n workflow that maps how money leaves your inbox. In one run it searches your Gmail for receipts and payment notices
from seven payment rails: PayPal, Apple, Google Play, Google Pay, Stripe or Paddle, SEPA direct debit and Klarna. A Code
step reads the amount and the last four card digits from each message and marks it as verified or uncertain. Every message
becomes a row in a Google Sheet. It uses no AI model, downloads no attachment and changes nothing in your mailbox.

What is inside

• workflow.json: the workflow as n8n exports it, sixteen nodes. Four are sticky notes. It holds no credential.
• README.md: these notes.

What we changed from the original copy

• The seven Gmail nodes asked for 200 messages with an option called maxResults, which the Gmail node does not have. With
  no limit set, the node returns 50. Each node now has the limit 200.
• Classify rails read the keys subject, from and date. The simplified Gmail output names them Subject and
  From, and gives the date as internalDate in milliseconds. The code now reads both spellings and turns the
  milliseconds into a date, so the merchant, sender and last charge columns are filled.
• Append sheet used Append or Update Row, which needs a column to match on and stops without one. It now uses Append
  Row, which is what the sticky notes describe.
• The sheet id, which was the placeholder REPLACE_SHEET_ID, is now <YOUR_SHEET_ID>. The credential ids, which were
  REPLACE, are gone.
• The main sticky note has a shorter title, and its setup lines no longer mention REPLACE.

Before you start

• A Gmail account you can connect to n8n with OAuth2.
• A Google account for a Google Sheets OAuth2 credential, and a Google Sheet with a tab called rails. The tab can be
  empty: n8n writes the column names from the first run.

Set it up

1. In n8n, create a workflow, open its menu and choose Import from File. Pick workflow.json.
2. Add a Gmail OAuth2 credential and select it in the seven nodes whose names start with Gmail.
3. Add a Google Sheets OAuth2 credential and select it in Append sheet. Replace <YOUR_SHEET_ID> with your sheet's id,
   the part of its address between /d/ and /edit.
4. Open Set window and set WINDOW_AFTER to the date you want to search from, written as YYYY/MM/DD.
5. Choose Execute workflow and open your sheet.
6. Read the evidence column before you cancel anything.

How a run goes

1. When clicking ‘Execute workflow’ starts the run, and Set window holds the start date.
2. Seven Gmail nodes search in parallel, each for one rail. A rail's search combines the sender or the subject with words
   such as receipt, invoice, payment, abonnement or incasso. Each returns up to its limit, and none downloads an
   attachment. A search with no result still passes an empty item on.
3. Wait for all rails is a Merge node with seven inputs. It waits for every search to finish.
4. Classify rails skips the empty items and builds one row for each message. A row holds the rail, the merchant (the
   subject), the amount, the currency, the date, the last four card digits, the evidence, a note, the sender and a snippet.
5. Append sheet adds the rows to the rails tab.

Change the result

• The rails and their search words: the q search in each Gmail node. Add a Gmail node and a line in the rails list in
  Classify rails for a new rail, and raise the inputs of Wait for all rails.
• The start date: WINDOW_AFTER in Set window.
• How many messages each rail returns: the limit in each Gmail node, at most 500.
• What counts as evidence: the code in Classify rails.

Good to know

• The start date 2025/08/01 in the original copy was meant as a window of about 13 months. On 12 November 2026 it covers
  about 15. Set it to the date you want.
• The search words are English and Dutch, as in the original copy. Change them to the words your senders use.
• An amount is found only when it appears in the subject or in the snippet, in euros or dollars. Nothing is converted.
• A message is marked VERIFIED when it has an amount and UNCERTAIN when it has none. A "card added" notice is never a
  charge.
• Each run adds the rows again. Running it twice doubles them, so clear the tab or change the start date first.
• Household direct debits, such as rent or a phone plan, often send no email. A missing row is not proof that there is
  no payment.
• The workflow reads only the metadata and the snippet of each message. It writes no label and sends no mail.
• Mindket did not run this workflow against Gmail or Google Sheets. These notes follow n8n's published node code, read on
  12 November 2026, and the Code step was run on sample messages on a local computer.