How do I check my post office Passbook balance?

Now You can Check your post office passbook online with your mobile number and OTP. 

But You need an account Number, Linked Mobile Number, and OTP. 

Link for Online Passbook = https://www.ippbonline.com/web/ippb/dop-product-payment

and if Your Question is- How can I check my post office account online?

then the answer is the same- Just click on this link and fill details- 

Post office e-passbook - https://www.ippbonline.com/web/ippb/dop-product-payment

Some Other questions answered in this article- 

How can I check my post office balance in mobile?

Just click on this link - https://www.ippbonline.com/web/ippb/dop-product-payment

How do I download passbook from post office?

Just click on above link and you can download in PDF.