Twilio SMS API
SMS, WhatsApp, voice calls and verification for 180+ countries
Freemium
✓ Verified
🇺🇸 United States
Twilio is the gold standard for programmable communications. The API covers SMS, WhatsApp messaging, voice calls, video, 2FA/OTP verification (Verify), and push notifications. Used by millions of developers globally for user authentication, customer notifications, two-factor auth, appointment reminders, and conversational AI. Pricing is per message ($0.0079 per outbound SMS in the US). The free trial credit of $15 is enough to test all features. Twilio Verify is the simplest solution for adding phone number verification to any app.
API Details
Auth Method
API Key
Pricing Model
Freemium
Free Tier
Yes — $15 free trial credit
Rate Limit
100 SMS/second
Format
REST / JSON
Versioning
2010-04-01
SLA / Uptime
99.95%
Compliance
SOC 2, HIPAA, GDPR, ISO 27001
Geographic Restrictions
180+ countries for SMS
Last Verified
2026-02-20
Categories
Frequently Asked Questions
Twilio SMS pricing: outbound SMS in the US is $0.0079 per message (less than 1 cent). Inbound SMS is $0.0075 per message. Toll-free numbers cost $0.0045/message. Phone number rental is $1.15/month for local numbers. International rates vary significantly by country. WhatsApp Business API via Twilio is $0.005u2013$0.090 per conversation by country.
You rent a virtual phone number from Twilio (from $1.15/month for local US numbers) to send and receive SMS. You can also use Twilio's Alphanumeric Sender ID (your brand name instead of a number) for outbound-only in supported countries. For the US, A2P 10DLC registration is required for business messaging.
A2P 10DLC (Application-to-Person 10-Digit Long Code) is a US carrier registration system for business SMS. Since 2021, all businesses sending SMS from 10-digit local numbers in the US must register their brand and campaigns with The Campaign Registry (TCR) via Twilio. Without registration, messages will be filtered or blocked. Registration costs $4u2013$10/month plus a one-time setup fee.
Yes. Twilio provides access to the WhatsApp Business API. You can send template messages (pre-approved message formats) to opted-in users and respond to user-initiated conversations within 24 hours (free). WhatsApp via Twilio requires a registered WhatsApp Business Account and Meta's approval for your business. Pricing is per 24-hour conversation window.