/oauth

name: oauth
description: Configure OAuth providers (Google, Apple, Microsoft, Facebook, GitHub, etc.) to work with portless local dev URLs. Use when setting up OAuth redirect URIs, fixing "redirect_uri_mismatch" or "invalid redirect" errors, configuring sign-in providers for local development, or when a provider rejects .localhost subdomains. Triggers include "OAuth not working with portless", "redirect URI mismatch", "Google/Apple/Microsoft sign-in fails locally", "configure OAuth for local dev", or any task involving OAuth callback URLs with portless domains.

OAuth with Portless

OAuth providers validate redirect URIs against domain rules. `.localhost` subdomains fail on most providers because they are not in the Public Suffix List or are explicitly blocked. Portless fixes this with `--tld` to serve apps on real, valid domains.

The Problem

When portless uses the default `.localhost` TLD, OAuth providers reject redirect URIs like `http://myapp.localhost:1355/callback`:

| Provider | `localhost` | `.localhost` subdomains | Reason | | --------- | ----------- | ----------------------- | ------------------------------ | | Google | Allowed | Rejected | Not in their bundled PSL | | Apple | Rejected | Rejected | No localhost at all | | Microsoft | Allowed | Allowed | Permissive localhost handling | | Facebook | Allowed | Varies | Must register each URI exactly | | GitHub | Allowed | Allowed | Permissive |

Google and Apple are the strictest. Microsoft and GitHub are more lenient with localhost.

The Fix

Use a valid TLD so the redirect URI passes provider validation:

portless proxy start --tld dev
portless myapp next dev
# -> https://myapp.dev

Any TLD in the Public Suffix List works: `.dev`, `.app`, `.com`, `.io`, etc.

Use a domain you own

Bare TLDs like `.dev` mean `myapp.dev` could collide with a real domain. Use a multi-segment TLD under a domain you control, so the app name stays clean and the domain structure lives in the TLD:

portless proxy start --tld local.yourcompany.dev
portless myapp next dev
# -> https://myapp.local.yourcompany.dev

This ensures no outbound traffic reaches something you don't own. For teams, set a wildcard DNS record (`*.local.yourcompany.dev -> 127.0.0.1`) so every developer gets resolution without `/etc/hosts`, and every developer shares the same redirect URIs in the provider console.

Provider Setup

Google

1. Go to [Google Cloud Console > Credentials](https://console.cloud.google.com/apis/credentials) 2. Create or edit an OAuth 2.0 Client ID (Web application) 3. Add the portless domain to **Authorized JavaScript origins**: `https://myapp.dev` 4. Add the callback to **Authorized redirect URIs**: `https://myapp.dev/api/auth/callback/google`

Google validates domains against the Public Suffix List. The domain must end with a recognized TLD. `.localhost` subdomains fail this check; `.dev`, `.app`, `.com`, etc. all pass.

HTTPS is required for `.dev` and `.app` (HSTS-preloaded). Portless handles this automatically with `--https`.

Apple

Apple Sign In does not allow `localhost` or IP addresses at all.

1. Go to [Apple Developer > Certificates, Identifiers & Profiles](https://developer.apple.com/account/resources) 2. Register a Services ID 3. Configure Sign In with Apple, adding the portless domain as a **Return URL**: `https://myapp.dev/api/auth/callback/apple`

The domain must be a real, publicly-resolvable domain name. Since portless maps the domain to 127.0.0.1 locally, the browser resolves it but Apple's server-side validation may require the domain to resolve publicly too. If Apple rejects the domain, add a public DNS A record pointing to 127.0.0.1 for your dev subdomain.

Microsoft (Entra / Azure AD)

1. Go to [Azure Portal > App registrations](https://portal.azure.com/#view/Microsoft_AAD_RegisteredApps) 2. Create or edit an app registration 3. Under **Authentication**, add a **Web** redirect URI: `https://myapp.dev/api/auth/callback/azure-ad`

Microsoft allows `http://localhost` with any port for development. It also accepts `.localhost` subdomains in most cases. Using a custom TLD with portless is still recommended for consistency across providers.

Facebook (Meta)

1. Go to [Meta for Developers > App Dashboard](https://developers.facebook.com/apps/) 2. Under **Facebook Login > Settings**, add the portless URL to **Valid OAuth Redirect URIs**: `https://myapp.dev/api/auth/callback/facebook`

Facebook requires each redirect URI to be registered exactly (no wildcards). Strict Mode (enabled by default) enforces exact matching.

GitHub

1. Go to [GitHub Developer Settings > OAuth Apps](https://github.com/settings/developers) 2. Set **Authorization callback URL**: `https://myapp.dev/api/auth/callback/github`

GitHub is permissive with localhost and subdomains. A custom TLD is not strictly required but keeps the setup consistent.

Auth Library Configuration

NextAuth / Auth.js

Set `NEXTAUTH_URL` to match the portless domain:

NEXTAUTH_URL=https://myapp.dev

NextAuth uses this to construct callback URLs. Without it, callbacks may use `localhost` and cause a mismatch.

Passport.js

Set the `callbackURL` in each strategy to use the portless domain:

new GoogleStrategy({
  clientID: process.env.GOOGLE_CLIENT_ID,
  clientSecret: process.env.GOOGLE_CLIENT_SECRET,
  callbackURL: process.env.BASE_URL + "/auth/google/callback",
});

Set `BASE_URL=https://myapp.dev` in your environment.

Generic / Manual

Read the `PORTLESS_URL` environment variable that portless injects into the child process:

const baseUrl = process.env.PORTLESS_URL || "http://localhost:3000";
const callbackUrl = `${baseUrl}/auth/callback`;

Troubleshooting

"redirect_uri_mismatch" or "invalid redirect URI"