Indian immigration authorities said that foreign workers in the United States with H1B work visas may work for multiple companies.

The H1B visa is a non-immigrant visa that allows U.S. companies to hire foreign workers in areas of expertise that require theoretical or technical expertise.

Technology companies rely on H1B work visas to hire tens of thousands of workers a year from countries such as India and China.
H1B companies
According to a USCIS twitter post yesterday, H1B workers can work for multiple employers, but each employer must file an I-129 application before the worker starts work.
H1B visa quota
Under congressional rules, H1B visas are capped at 65,000 a year, with an additional 20,000 available to beneficiaries with us master’s degree or higher.
In addition, H1B staff employed by institutions of higher education or their affiliated or related non-profit entities, non-profit research institutions or government research institutions are not subject to this cap.