DocuSign OAuth 2.0 Migration Guide: JWT, Auth Code Grant, and a Simpler Alternative

const jwt = require('jsonwebtoken');

const now = Math.floor(Date.now() / 1000);
const token = jwt.sign(
  {
    iss: YOUR_INTEGRATION_KEY,
    sub: YOUR_USER_ID,  // GUID from DocuSign Admin
    aud: "account-d.docusign.com",  // or account.docusign.com for prod
    iat: now,
    exp: now + 3600,
    scope: "signature impersonation",
  },
  YOUR_RSA_PRIVATE_KEY,
  { algorithm: "RS256" }
);

const res = await fetch("https://account-d.docusign.com/oauth/token", {
  method: "POST",
  headers: { "Content-Type": "application/x-www-form-urlencoded" },
  body: new URLSearchParams({
    grant_type: "urn:ietf:params:oauth:grant-type:jwt-bearer",
    assertion: token,
  }),
});

const { access_token, expires_in } = await res.json();
// access_token is valid for 1 hour
// You MUST refresh before expiry

// Replace the old X-DocuSign-Authentication header:
// ❌ OLD: "X-DocuSign-Authentication": JSON.stringify({...})
// ✅ NEW:
const res = await fetch(`https://${baseUri}/restapi/v2.1/accounts/${accountId}/envelopes`, {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "Authorization": `Bearer ${access_token}`,
  },
  body: JSON.stringify(envelopeDefinition),
});

// No JWT. No RSA keys. No consent flow. No token refresh.
const res = await fetch("https://signb.ee/api/v1/send", {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "Authorization": "Bearer YOUR_API_KEY",  // That's it.
  },
  body: JSON.stringify({
    markdown: "# Your Document\n\nContent here...",
    recipient_name: "Jane Smith",
    recipient_email: "jane@example.com",
  }),
});