Twilio Messaging provides pay-per-use APIs for SMS, MMS, WhatsApp, and voice messaging with no monthly minimums. Uses per-message and per-minute billing with global coverage.

Twilio offers flexible, usage-based pricing across SMS, MMS, voice, email, WhatsApp, and video APIs. SMS costs $0.0079-0.0083 per message segment in the US with carrier surcharges. Each service is billed separately. New accounts receive $15 free credit.
Flexible SMS, MMS, Voice, WhatsApp and Video APIs
G2 Rating
Starting Price
Funding
SMS marketing platform with mobile coupons and text surveys
G2 Rating
Starting Price
SlickText is an SMS marketing platform offering 9 tiered plans starting at $29/month for 500 messages. Features include mass texting, scheduled messaging, contact management, and advanced analytics with rollover credits.
WhatsApp Business API and SMS unified on a single phone number
Founded
Telnyx now supports WhatsApp Business messaging, allowing you to register numbers, manage WABAs, send templates, and handle two-way conversations via the Telnyx API and portal. You can use PSTN, SMS, WhatsApp messaging, and WhatsApp calls on a single Telnyx number.
Multi-channel SMS, Email, and WhatsApp messaging platform
Starting Price
Textmagic offers flexible pay-as-you-go SMS and multichannel communication with 2-way messaging, contact management, and automation. US SMS costs approximately $0.049 per message.