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Enabling Google OAuth Locally for n8n: macOS and Windows Guide

  • Writer: Revanth Reddy Tondapu
    Revanth Reddy Tondapu
  • Aug 15
  • 3 min read

For reliable, no-hassle local testing of Google OAuth with n8n on macOS or Windows, use the Installed (Desktop) app flow. If you require a public callback URL for full browser-based flows, only a custom, verified domain pointed to your tunnel (e.g., ngrok) satisfies Google’s domain requirements—public tunnels alone (ngrok.io, localhost.run) cannot be authorized.


Enabling Google OAuth Locally
Enabling Google OAuth Locally

1. Why Local OAuth Requires Special Handling

Google’s OAuth consent screen demands that any domain you list be:

  • A top-level domain you own and verify in Google Search Console.

  • Present in your OAuth client’s Authorized redirect URIs.

“localhost” and multi-tenant tunnels (ngrok.io, localhost.run) are not owner-verified, so Google blocks them.


2. Method 1: Desktop (Installed) App OAuth Client

Best for: Quick local development on macOS or Windows—no public URL required.


Why It Works

Installed applications bypass the Authorized Domains check and permit localhost redirect URIs.


Step-by-Step (macOS & Windows)

  1. Sign in to Google Cloud Console, select your project.

  2. Go to APIs & Services > Credentials.

  3. Click Create Credentials > OAuth client ID.

  4. Choose Application type: Desktop app.

  5. Name it (e.g., “n8n Local Dev”) and click Create.

  6. Copy the generated Client ID and Client Secret.

  7. In n8n credentials (UI or environment variables), set:

N8N_OAUTH2_CREDENTIALS_GOOGLE_CLIENT_ID=<Client ID> N8N_OAUTH2_CREDENTIALS_GOOGLE_CLIENT_SECRET=<Client Secret>

  1. Ensure your OAuth node’s redirect URI is:

  1. Start n8n:

    • macOS & Windows:

n8n start

  1. Trigger the OAuth flow in n8n. Google redirects to localhost, and n8n captures the token automatically.

Result: OAuth completes successfully without domain or tunnel setup.


3. Method 2: Custom Domain + Tunnel (Advanced)

Best for: Full browser-based OAuth flows (webhooks, CORS) on macOS or Windows.

Overview

  1. Use a domain you control and verify in Search Console.

  2. Point a subdomain at your tunnel endpoint.

  3. Add your root domain to Authorized domains.

  4. Configure a Web application OAuth client with the custom subdomain callback.


Step-by-Step

A. Domain & DNS Configuration

n8n.dev-example.com CNAME <your-ngrok-subdomain>.ngrok-free.app

B. Google Cloud Settings

  1. OAuth consent screen > Branding

  2. APIs & Services > Credentials

  3. Create/Edit OAuth client ID → Web application.

  4. Under Authorized redirect URIs, add:

C. Tunnel Setup

  • Install and run your tunnel tool (ngrok, Cloudflare Tunnel, etc.) on macOS or Windows:

# ngrok example
ngrok http 5678

D. n8n Configuration

  • In OAuth credentials, set:

Auth URI:     https://accounts.google.com/o/oauth2/auth
Token URI:    https://oauth2.googleapis.com/token
Redirect URI: https://n8n.dev-example.com/rest/oauth2-credential/callback
Client ID/Secret: (from Web application client)

E. Run & Verify


4. Platform-Specific Tunnel Installation

Platform

ngrok Install

Alternative Tunnel

macOS

brew install --cask ngrok

Cloudflare: brew install cloudflared

Windows

Download from ngrok.com, add to PATH

Cloudflare: Download and install cloudflared CLI


5. Troubleshooting & Tips

  • 401 Unauthorized: Expected for /rest/login before n8n session; harmless.

  • Redirect URI mismatch: Ensure exact match of protocol, domain, port, and path.

  • Domain save errors: Public tunnel domains can’t be added—use Desktop App or verified domain.

  • Tunnels expire: Free ngrok URLs change each session; adjust DNS/CNAME or upgrade for fixed subdomains.


6. Method Comparison

Method

Domain Ownership Req’d?

Authorized Domains

Setup Effort

Use Case

Desktop App OAuth

No

Not needed

Low

Simple localhost testing

Custom Domain + Tunnel

Yes

Verified domain

High

Full web-app OAuth flows

Public Tunnel Only (ngrok)

No

Not allowed

Medium

Non-Google OAuth or short tests


✅ Summary

  • Desktop (Installed) App OAuth is the fastest, works on both macOS and Windows with no domain hurdles.

  • Custom domain + tunnel is the only way to meet Google’s domain requirements for web application OAuth flows.

  • Public tunnels alone cannot satisfy Google’s consent screen rules and are best reserved for non-Google OAuth tests.


Choose the method that aligns with your development needs and environment to ensure smooth, local testing of Google OAuth with n8n.

 
 
 
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