Authy (by Twilio) is a two-factor authentication (2FA) service based on TOTP via mobile apps or SMS. It supports push authentication, backup and restore, multi-device sync, and secure authentication APIs to integrate TOTP flows into services.

Authy’s core app functions (TOTP generation) work offline. However, SMS delivery for TOTP in China is unreliable and often blocked due to carrier filtering. Push notifications and cloud backup may fail due to restricted connections with Twilio servers. Developers targeting China often use local 2FA solutions such as Tencent Cloud MFA or Alibaba Cloud MFA, which provide SMS, voice, or push authentication services that integrate with Chinese telecom systems and comply with regional identity verification regulations.

The information regarding service availability in China is provided for general reference purposes only. Due to the dynamic nature of network conditions and regulatory environments, the actual accessibility of these services may vary over time and by location. Users are advised to verify the current status independently.