Auth0 Machine-to-Machine — Securing Service-to-Service Communication with Auth0

DodaTech Updated 2026-06-28 1 min read

In this tutorial, you'll learn about Auth0 Machine To Machine. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

Auth0 M2M authentication enables secure service-to-service communication using the OAuth 2.0 Client Credentials flow.

// M2M token acquisition
const axios = require('axios');

async function getM2MToken() {
  const response = await axios.post(`https://${tenant}.auth0.com/oauth/token`, {
    client_id: process.env.AUTH0_CLIENT_ID,
    client_secret: process.env.AUTH0_CLIENT_SECRET,
    audience: 'https://scan-api.example.com',
    grant_type: 'client_credentials'
  });

  return response.data.access_token;
}

// M2M token validation on the API
async function validateM2MRequest(req, res, next) {
  const token = req.headers.authorization?.split(' ')[1];
  const decoded = jwt.verify(token, jwksClient.getSigningKey, {
    issuer: `https://${tenant}.auth0.com/`,
    audience: 'https://scan-api.example.com',
    algorithms: ['RS256']
  });

  // Check client-specific permissions
  const clientId = decoded.azp;
  const permissions = decoded.permissions || [];
  if (!permissions.includes('scan:write')) {
    return res.status(403).json({ error: 'insufficient_permissions' });
  }

  next();
}

M2M tokens should be cached and reused until expiry to minimize authentication overhead.

← Previous Auth0 Security Best Practices — Securing Your Auth0 Implementation Next → Auth0 Custom Domains — Configuring Custom Domains in Auth0

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