How to fix Error: Maximum number of redirects exceeded (circular redirects) in Node.js

const axios = require('axios');

axios.interceptors.request.use(request => {
  console.log('Requesting:', request.url);
  return request;
});

axios.interceptors.response.use(response => {
  if (response.status >= 300 && response.status < 400) {
    console.log('Redirect from:', response.config.url);
    console.log('Redirect to:', response.headers.location);
  }
  return response;
});

try {
  await axios.get('https://example.com/api/endpoint');
} catch (err) {
  console.error('Failed after redirects:', err.message);
}

// BAD: Creates circular redirect
app.get('/api/login', (req, res) => {
  if (!req.session.user) {
    res.redirect('/auth'); // Redirects to auth
  }
});

app.get('/auth', (req, res) => {
  if (!req.query.token) {
    res.redirect('/api/login'); // Redirects back to login - LOOP!
  }
});

// GOOD: Properly handle authentication flow
app.get('/api/login', (req, res) => {
  if (!req.session.user) {
    res.redirect('/auth?returnUrl=/api/login');
  } else {
    res.json({ user: req.session.user });
  }
});

app.get('/auth', (req, res) => {
  // Show login form or handle OAuth without redirecting back
  res.render('login', { returnUrl: req.query.returnUrl });
});

// With axios
const axios = require('axios');

const response = await axios.get('https://example.com/api', {
  maxRedirects: 30 // Default is 21
});

// With follow-redirects directly
const { https } = require('follow-redirects');

https.get({
  host: 'example.com',
  path: '/api',
  maxRedirects: 30
}, (response) => {
  // Handle response
});

// With node-fetch (using follow-redirects wrapper)
const fetch = require('node-fetch');

const response = await fetch('https://example.com/api', {
  follow: 30 // Maximum redirects to follow
});

// With axios
const axios = require('axios');

async function fetchWithManualRedirects(url, maxRedirects = 5) {
  let redirectCount = 0;
  let currentUrl = url;

  while (redirectCount < maxRedirects) {
    const response = await axios.get(currentUrl, {
      maxRedirects: 0,
      validateStatus: (status) => status < 400 // Don't throw on 3xx
    });

    if (response.status >= 300 && response.status < 400) {
      const location = response.headers.location;

      if (location === currentUrl) {
        throw new Error('Circular redirect detected');
      }

      console.log(`Redirect ${redirectCount + 1}: ${currentUrl} -> ${location}`);
      currentUrl = new URL(location, currentUrl).href;
      redirectCount++;
    } else {
      return response;
    }
  }

  throw new Error('Maximum redirects exceeded');
}

const response = await fetchWithManualRedirects('https://example.com/api');

const axios = require('axios');

const visitedUrls = new Set();

const response = await axios.get('https://example.com/api', {
  beforeRedirect: (options, responseDetails) => {
    const nextUrl = options.href || options.url;

    if (visitedUrls.has(nextUrl)) {
      throw new Error(`Circular redirect detected: ${nextUrl}`);
    }

    visitedUrls.add(nextUrl);
    console.log('Redirecting to:', nextUrl);
  }
});