Pavel Durov, the founder of the app, which has more than 900 million users, was taken into custody by the French authorities.

Drug dealers, scammers and white nationalists openly conduct business and spread toxic speech on the platform, according to a Times analysis of more than 3.2 million Telegram messages.

The arrest of Telegram’s chief executive in France has ignited a debate about moderation on his app.

Telegram, the popular messaging app, has blocked a number of channels with ties to Hamas. The move followed Apple and Google coming under pressure from outside groups to force Telegram to block ...

Telegram is a cross-platform messaging service with enhanced security and privacy thanks to various levels of encryption.