Price finding browser extension InvisbleHand is to enter the car rental sector and plans to expand to cover major travel sites.
The company claims to typically save users an average of £48 when hiring a car worldwide and as much as £102 when renting in destinations such as Rome.
It is available on all major web browsers, including Internet Explorer, Chrome, Safari and Firefox.
Founder Robin Landy said: “Even if you are searching on a car rental site, InvisibleHand will automatically tell you if it can find a cheaper car elsewhere.
“This is about technology putting the power back into the hands of consumers so that they can be confident of getting a good deal every time.”
InvisibleHand is free to download via www.getinvisiblehand.com.