Most debit cards do have limits for your protection.
The limit or spending limit on your debit card depends on your bank.
However most debit cards have daily spending and withdraw limits of $1,000.00 to $3,000.00 per day.
This is pretty reasonable because unless you're rich then you wouldn't be spending even $1,000.00 per day.
Paying online with a debit card is safe.
As long as you're on a legit website that has the lock Icon in the address bar and has the https: then the website is secure.
When you use your debit card or credit card online the website owner does not see your debit card information or credit card information.
Your credit card or debit card is processed by a third party credit card processor.
When you pay for something online with your debit card or credit card the payment goes through a payment processor.
Then the payment processor eventually releases your payment to the company you paid the money too within a week.