Reddit OAuth2

Reddit login is optional and controlled by REDDIT_AUTH_ENABLED. When disabled, Reddit endpoints return 503 Service Unavailable. Reddit OAuth2 uses the identity scope and does not expose an email address. The API assigns a stable synthetic email {redditId}@users.noreply.reddit.com for account upsert. Token exchange uses HTTP Basic auth; profile fetch uses Bearer + a required User-Agent. JWTs are never placed in the redirect URL; the API issues a one-time exchangeCode (Redis, 60 seconds). The same POST /auth/exchange endpoint is shared with other social providers.

• • Feature-flagged via environment
• • Custom passport-oauth2 strategy + RedditAuthGuard
• • Profile fetched via GET https://oauth.reddit.com/api/v1/me (Authorization: Bearer + User-Agent)
• • Scope identity — Reddit username and id only; no email
• • Token exchange at https://www.reddit.com/api/v1/access_token uses HTTP Basic auth
• • Synthetic {redditId}@users.noreply.reddit.com — not deliverable
• • Redirect allowlist prevents open redirects
• • Same token response shape as POST /auth/login

Create a web app at reddit.com/prefs/apps. Set the redirect URI to match REDDIT_CALLBACK_URL and request the identity scope during authorization.

1. Open https://www.reddit.com/prefs/apps
2. Scroll to "developed applications" and click create another app... (or create app)
3. Choose type web app
4. Enter a name and set redirect uri to your Nest API callback (e.g. http://localhost:3000/api/v1/auth/reddit/callback)
5. Copy the client id (under the app name) and client secret
6. Ensure REDDIT_CALLBACK_URL matches the redirect uri registered in Reddit
7. The API requests scope identity — Reddit does not return email via this scope

Loaded from .env via src/config/reddit-oauth.config.ts (namespace redditOAuth on ConfigService). See .env.example.

REDDIT_AUTH_ENABLED=true
REDDIT_CLIENT_ID=your-reddit-client-id
REDDIT_CLIENT_SECRET=your-reddit-client-secret
REDDIT_CALLBACK_URL=http://localhost:3000/api/v1/auth/reddit/callback
REDDIT_REDIRECT_ALLOWLIST=myapp://success,http://localhost:5173/auth/callback
REDDIT_OAUTH_DEFAULT_ROLES=

New Reddit users receive roles: [] by default (same as password register). Set REDDIT_OAUTH_DEFAULT_ROLES in .env to a comma-separated list of Role values (e.g. user or user,manager). Existing users linked by redditId keep their current roles.

1. Client opens GET /api/v1/auth/reddit?redirect=<allowlisted URL>
2. User consents on Reddit; browser hits GET /api/v1/auth/reddit/callback
3. API exchanges code via HTTP Basic at access_token, calls GET https://oauth.reddit.com/api/v1/me, upserts user, stores exchangeCode in Redis, redirects to redirect?code=...
4. Client POSTs { code } to /api/v1/auth/exchange and receives JWTs

Same pattern as other OAuth providers: start login in the browser; your callback route reads code from the query string and calls exchange. The user object includes redditId and a synthetic email — do not use it for outbound mail.

const API = 'http://localhost:3000/api/v1';
const redirect = encodeURIComponent(
  'http://localhost:5173/auth/callback'
);

// Full-page redirect to Nest → Reddit → back to SPA
window.location.href = `${API}/auth/reddit?redirect=${redirect}`;

// /auth/callback on the SPA
const params = new URLSearchParams(window.location.search);
const code = params.get('code');
if (!code) throw new Error('Missing exchange code');

const res = await fetch('http://localhost:3000/api/v1/auth/exchange', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ code }),
});
if (!res.ok) throw new Error(await res.text());

const { user, accessToken, refreshToken } = await res.json();
// persist tokens as your app requires
sessionStorage.setItem('accessToken', accessToken);
// Reddit has no real email — use redditId as the stable identifier
console.log('signed in', user.redditId);

• • Add your frontend callback URL to REDDIT_REDIRECT_ALLOWLIST (e.g. http://localhost:5173/auth/callback)
• • REDDIT_CALLBACK_URL must point at the Nest API, not the SPA
• • Reddit never returns a real email — user.email is synthetic and not deliverable
• • Store accessToken / refreshToken securely (memory + httpOnly cookie patterns as you prefer)

Use a custom scheme (or universal link) in the allowlist. After Reddit OAuth, the API redirects to myapp://success?code=.... The app opens, parses the code, and calls exchange.

import * as Linking from 'expo-linking';
import * as WebBrowser from 'expo-web-browser';

const API = 'https://api.example.com/api/v1';
const redirect = encodeURIComponent('myapp://success');

async function signInWithReddit() {
  const url = `${API}/auth/reddit?redirect=${redirect}`;
  await WebBrowser.openAuthSessionAsync(url, 'myapp://success');
}

import * as Linking from 'expo-linking';

async function exchangeFromUrl(url) {
  const { queryParams } = Linking.parse(url);
  const code = queryParams?.code;
  if (!code) return;

  const res = await fetch(`${API}/auth/exchange`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ code }),
  });
  const data = await res.json();
  // data.accessToken, data.refreshToken, data.user
  return data;
}

Linking.addEventListener('url', ({ url }) => {
  exchangeFromUrl(url);
});

• • Register the scheme in the OS / Expo app.json
• • Prefer Linking.addEventListener('url', ...) and getInitialURL()
• • Exchange over HTTPS against your API base URL
• • Identify users by redditId — not by synthetic email

• • Redirect URLs must match REDDIT_REDIRECT_ALLOWLIST prefixes
• • Exchange codes are single-use and expire in 60 seconds (Redis)
• • Reddit never provides email — synthetic address is for internal upsert only, not notifications
• • Existing accounts are linked by redditId; email-based linking does not apply to Reddit-only users
• • Reddit API requires a descriptive User-Agent on profile requests
• • Reddit-only users have password null — password login / change-password will fail until a password is set

Postgres entity / interface fields used by Reddit login:

• • redditId — unique nullable Reddit user id (id from /api/v1/me)
• • email — synthetic {redditId}@users.noreply.reddit.com (Reddit does not expose email)
• • password — nullable for OAuth-only accounts
• • isActive — set true for new Reddit users
• • roles — from REDDIT_OAUTH_DEFAULT_ROLES env (default [])

• Social Authentication hub
• Google OAuth2 guide
• Facebook OAuth2 guide
• X / Twitter OAuth2 guide
• GitHub OAuth2 guide
• Figma OAuth2 guide
• LinkedIn OpenID Connect guide
• Slack OpenID Connect guide
• Atlassian OAuth 2.0 (3LO) guide
• GitLab OAuth2 guide
• Bitbucket OAuth2 guide
• Discord OAuth2 guide
• Twitch OAuth2 guide
• Steam OpenID 2.0 guide
• Auth & JWT