n8n Credential Setup Guide

Both Gmail and Google Sheets use the same Google Cloud project (esquire-automation). You only need to create the project once.

Do this once. If the esquire-automation project already exists, skip to section 2 or 3.

Create the Project

1. Go to console.cloud.google.com and sign in with the Esquire Google account
2. Click the project dropdown at the top → New Project → name it esquire-automation → Create

Enable Required APIs

1. Go to APIs & Services → Library
2. Search Gmail API → Enable
3. Search Google Sheets API → Enable
4. Search Google Drive API → Enable

OAuth Consent Screen (required for Gmail OAuth2 only)

1. Go to APIs & Services → OAuth consent screen → Audience
2. Set User Type to External → Save
3. Go to Branding → App name: Esquire Automation, support email, developer email → Save
4. Go back to Audience → under Test users → add the email of whoever will connect Gmail → Save

Step 1 — Create OAuth Client in Google Cloud

1. Go to APIs & Services → Credentials → Create Credentials → OAuth client ID
2. Application type: Web application → Name: n8n-google
3. Under Authorized redirect URIs → Add URI → enter exactly:
   
   

   https://n8n.esquireembroidery.com/webhook/rest/oauth2-credential/callback

4. Click Create → copy the Client ID and Client Secret shown in the dialog

Step 2 — Add Credential in n8n

1. In n8n, open a workflow → add a Gmail node → click the credential field → Create New Credential → Gmail OAuth2 API
2. Paste the Client ID and Client Secret
3. Click Sign in with Google → sign in with the Gmail account you want n8n to use
4. Approve the permissions → you should see Connection tested successfully

Important: n8n Server Config Requirement

The n8n server must have WEBHOOK_URL set correctly in /home/ec2-user/n8n.config.js — this is what determines the redirect URL n8n sends to Google. The current config is:

WEBHOOK_URL:         "https://n8n.esquireembroidery.com/webhook/"
N8N_EDITOR_BASE_URL: "https://n8n.esquireembroidery.com"

If n8n is ever reinstalled, verify both lines are present. After any config change, restart n8n:

pm2 delete n8n && pm2 start /home/ec2-user/n8n.config.js

Step 1 — Create Service Account in Google Cloud

1. Go to APIs & Services → Credentials → Create Credentials → Service Account
2. Name: n8n-sheets → click Create and Continue → skip optional steps → Done
3. Click on the n8n-sheets service account in the list
4. Go to the Keys tab → Add Key → Create new key → JSON → click Create
5. A JSON file downloads automatically — open it in a text editor (Notepad, VS Code, etc.)

Step 2 — Add Credential in n8n

1. In n8n, add a Google Sheets node → credential field → Create New Credential → Google Sheets Service Account
2. Copy "client_email" value from the JSON file → paste into Service Account Email
3. Copy the entire "private_key" value (including the -----BEGIN PRIVATE KEY----- and -----END PRIVATE KEY----- lines) → paste into Private Key
4. Click Save → you should see Connection tested successfully

Step 3 — Share Your Spreadsheet with the Service Account

1. Open the Google Sheet in your browser → click Share (top right)
2. Paste the service account email (from "client_email" in the JSON — looks like n8n-sheets@esquire-automation.iam.gserviceaccount.com)
3. Set role to Editor → uncheck "Notify people" → click Share

Step 1 — Get an API Key

1. Go to platform.openai.com → sign in or create an account
2. Click your profile icon (top right) → API Keys → Create new secret key
3. Name it n8n-po-automation → click Create
4. Copy the key immediately — you can only see it once. Paste it somewhere safe before closing the dialog.

Step 2 — Add Billing Credits

Step 3 — Add Credential in n8n

1. In n8n, add an OpenAI node → credential field → Create New Credential → OpenAI API
2. Paste the API key into the API Key field → click Save

Model to Use

When configuring the OpenAI node, select gpt-4.1 as the model. It produces the best results for reading and understanding email content and PO documents.