A French-American startup has launched an automatic password changer, leading a rival U.S. software firm to launch a similar service.

For most people, properly managing passwords verges on impossible, given the dizzying array of devices and websites on which we have become increasingly reliant. But Dashlane.com and LastPass are stepping up their offerings to counter hackers.

Dashlane, which was founded in Paris but is now based in New York, has acquired PassOmatic, a startup that created the automatic password changer it is building into its own products in coming weeks.