As the war in Ukraine unfolded last year, Russia’s best digital spies turned to new tools to fight an enemy on another front: those inside its own borders who opposed the war.

To aid an internal crackdown, Russian authorities had amassed an arsenal of technologies to track the online lives of citizens. After it invaded Ukraine, its demand grew for more surveillance tools. That helped stoke a cottage industry of tech contractors, which built products that have become a powerful — and novel — means of digital surveillance.

The technologies have given the police and Russia’s Federal Security Service, better known as the F.S.B., access to a buffet of snooping capabilities focused on the day-to-day use of phones and websites. The tools offer ways to track certain kinds of activity on encrypted apps like WhatsApp and Signal, monitor the locations of phones, identify anonymous social media users and break into people’s accounts, according to documents from Russian surveillance providers obtained by The New York Times, as well as security experts, digital activists and a person involved with the country’s digital surveillance operations.

President Vladimir V. Putin is leaning more on technology to wield political power as Russia faces military setbacks in Ukraine, bruising economic sanctions and leadership challenges after an uprising led by Yevgeny V. Prigozhin, the commander of the Wagner paramilitary group. In doing so, Russia — which once lagged authoritarian regimes like China and Iran in using modern technology to exert control — is quickly catching up.

“It’s made people very paranoid, because if you communicate with anyone in Russia, you can’t be sure whether it’s secure or not. They are monitoring traffic very actively,” said Alena Popova, a Russian opposition political figure and digital rights activist. “It used to be only for activists. Now they have expanded it to anyone who disagrees with the war.”

The effort has fed the coffers of a constellation of relatively unknown Russian technology firms. Many are owned by Citadel Group, a business once partially controlled by Alisher Usmanov, who was a target of European Union sanctions as one of Mr. Putin’s…