NylasConnect.callback()

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NylasConnect.callback() is a callback handler that works for both pop-up and inline authentication flows. This is the recommended method when handling OAuth callbacks on your backend.

Usage

Frontend (browser)Backend (required)

// In the browser, automatically uses window.location
const result = await nylasConnect.callback();

// On the backend, you MUST pass the full callback URL
const callbackUrl = `${req.protocol}://${req.get("host")}${req.originalUrl}`;
const result = await nylasConnect.callback(callbackUrl);

The url parameter is optional in the browser (defaults to window.location) but required on the backend since there’s no window object available.

When to use on backend

Use callback(url) on your backend when:

• You want to handle OAuth code exchange with client_secret (more secure than PKCE)
• You need to store tokens on the backend, not in the browser
• You want to link grants to users securely using a state parameter
• You’re making Nylas API calls from the backend using your API key

See the backend-handled OAuth flow guide for a complete example.

Parameters

Property	Type	Description
url	string?	The callback URL to process. Optional in browser (uses window.location). Required on backend.

Return value

The callback() method returns a Promise<ConnectResult> with the following properties.

Property	Type	Description
accessToken	string	The access token associated with the user’s grant.
expiresAt	number	When the access token will expire, in milliseconds using the Unix timestamp format.
grantId	string	A unique identifier for the user’s grant.
grantInfo	GrantInfo?	Optional grant information from the idToken.
idToken	string	An ID token containing information about the user.
scope	string	A space-delimited list of scopes associated with the user’s grant.

GrantInfo

Property	Type	Description
email	string	The email address associated with the grant.
emailVerified	boolean?	When true, indicates that the user has verified their email address.
familyName	string?	The user’s surname (last name).
givenName	string?	The user’s given (first) name.
id	string	A unique identifier for the user’s grant.
name	string?	The user’s display name.
picture	string?	A URL that links to the user’s profile picture.
provider	string	The OAuth provider that the user authenticated with.