jwtDecode function

JWTData jwtDecode(String token)

jwtDecode provides a way to decode different types of JWTs and extract their payloads, headers, expiration dates, and issued dates and whether they are expired or not.

You can use this function to decode a JWT and return a JWTData object:

final jwtData = jwtDecode(myToken);

print('header: ${jwtData.header}');
print('payload: ${jwtData.payload}');
print('isExpired: ${jwtData.isExpired}');
print('issued date: ${jwtData.issuedAt}');
print('expiration date: ${jwtData.expiration}');

Implementation

JWTData jwtDecode(String token) {
  final splitToken = token.split('.');
  if (splitToken.length != 3) {
    throw const FormatException('Invalid token');
  }

  final headerEncoded = splitToken[0];
  final payloadEncoded = splitToken[1];

  final normalizedHeader = base64.normalize(headerEncoded);
  final headerString = utf8.decode(base64.decode(normalizedHeader));
  final decodedHeader = jsonDecode(headerString) as Map<String, dynamic>;

  final normalizedPayload = base64.normalize(payloadEncoded);
  final payloadString = utf8.decode(base64.decode(normalizedPayload));
  final decodedPayload = jsonDecode(payloadString) as Map<String, dynamic>;

  return JWTData(header: decodedHeader, payload: decodedPayload);
}