How can I automatically reserve inventory once added to cart?

[Ciprian_Pop]

Hi, 

I run a small store with unique products. When I update the stock, customers are competing for them and it happened that some products were sold more than once. This caused some frustration and bad reviews from my customers. I understood that a reason is that the store is updating the stock only after it has confirmation from the payment provider for the payment. 

Is there an app that will block the stock when added to the cart and is having maybe a timer to set for the product to return to stock in case of not finishing the transaction in let's say 15 minutes?

I know about the implications that someone could block all the stock but I am willing to take this risk.

Thanks