Where can I find a free software to display error message using a callout similar to the Ajax ValidatorCallout.

Where can I find a free software to display error message using a callout similar to the Ajax ValidatorCallout.

Is there a reason for not using AJAX callout Extender?

Is there a reason for not using AJAX callout Extender?
(This reply was given to me in another forum)

The old applications I would like to improve have too many input fields.
I was looking for a solution that would require minimum changes to the pages.

I found a solution by searching enhanced callout.
Even though I had to buy it, I am happy to say that it solved my problem.