There are many pan card online service providers available in India, but NSDL and UTI are the main PAN Card providers.NDSL and UTI also provide online pan card application service, but their customer support is not better as compared to private pan card application service.
NSDL and UTI pan card services are very hassle-full and bad customer support. The pan card application will reject anytime if the applicant makes a little mistake.
All other online pan card application providers (Online agent companies/ websites) have franchise from NSDL and UTI for pan card processing, And they sent the application to NSDL or UTI after checking and correcting all the mistakes.
Private online pan card application providers (franchisee) are checks the details, do required corrections if you make any mistake and provides you a very good customer support then they sent the application to NSDL or UTI (Income tax department). So the application rejection chances are very low and applicant easily get the pan card.
Here the list of PAN Provides where Applicant can apply for the pan card.