How can I tell if someone has blocked me on WhatsApp?

There are a couple of indicators that you may be blocked:

1. You can no longer see a contact's last seen or online in the chat window. Learn more here.
2. You do not see updates to a contact's profile picture.
3. Any messages sent to a contact who has blocked you will always show one check mark (message sent), and never show a second check mark (message delivered). For more information on these check marks, read this article.
4. Any calls you attempt to place will not go through.

If you see all of the above indicators for a contact, this could mean that the person is blocking you. However, there are other possibilities. We have made this intentionally ambiguous in order to protect your privacy when you block someone. Thus, we cannot tell you if you are being blocked by someone else.

Not sure what blocking someone does? More details can be found here.

Learn how to block someone on: Android | iPhone | Windows Phone | Nokia S40 | BlackBerry | Nokia S60 | BlackBerry 10

Cheers,
WhatsApp Support Team