In Karnataka marriage certificates being available online. I do not know to which state of India you belongs to. The relevant link is below; You may find out such online system in your State.
You needn't visit the sub-registrar's office to get your marriage registered. Forget all the hassles, and apply and print your certificate online -all from your home.
Karnataka's stamps and registration department has decided to launch a dedicated portal, on the lines of property registration, to minimize visits to the government office.
"We are streamlining the process of getting marriage certificates online. Till now, you could apply online and obtain the certificate in person. We'll introduce the new system in a registrar's office in Bengaluru and roll it out in the rest of the state by yearend,'' inspector-general of registration and commissioner of stamps Manoj Kumar Meena told TOI. The system will integrate data from all the sub-registrar offices in the state to check multiple marriages by either groom or bride.