SAN FRANCISCO — San Francisco has reached a deal with short-term rental platforms Airbnb Inc. and Homeaway.com Inc. to end the companies' legal challenge to a local ordinance which threatens the companies with steep fines for listing properties not registered with the city.

The companies have agreed to take steps to make sure hosts who use their platforms are complying with a San Francisco law designed to keep owners from converting units for full-time residents into vacation rentals. They've also agreed to require that existing users show proof of their registration with the city and to direct new users to a portal to provide the required information to the city. The companies also agreed to provide the city on a monthly basis with listingsto allow the city to check that properties are properly registered.

U.S. District Judge James Donato, who has been overseeing the underlying lawsuit, had a strong hand in nudging the parties toward settlement. Last year, Donato turned back the companies' argument that the ordinance violates the First Amendment's free speech protections as well as Section 230 of the Communications Decency Act, which immunizes internet companies broadly from liability related to content created by users. Donato, however, blocked the city from enforcing the law, finding that San Francisco lacked any effective mechanism for companies to verify whether a particular property was registered. Donato referred the parties for settlement talks supervised by U.S. Magistrate Judge Jacqueline Scott Corley, who oversaw more than a dozen meetings between the two parties over the past six months.