There are a number of free chat services designed specifically for Tumblr. You can add a chat feature to your blog by copying some HTML code and pasting it into your Custom HTML editor on Tumblr. This gives visitors the ability to chat via text in real-time on your Tumblr page.

Babblr

Visit the Babblr webpage (link in Resources) and copy the chat button HTML from Option 2, so that it is visible on your public Tumblr page. Go to your Tumblr dashboard and click "Customize." Select "Custom HTML" and paste the code into the text editor, right before the "" tag. Click on the new Babblr icon on your Dashboard and sign in with your Twitter credentials.

CBox

Visit the CBox website (link in Resources) and sign up for an account. Select "Create My CBox" and choose "Publish." Copy the provided HTML code and paste it into the custom HTML editor on Tumblr.

Chatango

Visit the Chatango site and choose a chat window style, such as "Box," "Tab" or "Live Button." Type a custom chat group name into the text field and click "Create Group." Type in a username and password, then click "Sign Up." Copy the embed code and paste it into the custom HTML editor on Tumblr.