ClickSend

Business communications API platform that unifies SMS, email, voice, and direct mail delivery through a single integration. Sends transactional and marketing messages across channels with delivery tracking, scheduling, and webhook notifications.

Used by SMBs and enterprises for notifications, verification codes, and marketing campaigns. ClickSend differentiates by offering direct mail alongside digital channels, giving one API for SMS, email, and physical postcards or letters.

Key capabilities:

• REST API and SDKs for common languages
• SMS delivery to 190+ countries with fallback options
• Email sending with templates and tracking
• Voice calls and two-way SMS for verification flows
• Direct mail API for postcards and letters

Developers integrate ClickSend for OTP delivery, shipping notifications, appointment reminders, and multi-channel campaigns. Webhooks surface delivery status and replies for downstream automation.