ユーザ登録型アプリのSMS送信によるパスワード認証に必要なSMS-APIリスト（抜粋）
https://blog.api.rakuten.net/top-sms-api-twilio-way2sms/#Top_10_Best_SMS_APIs
| API | API Features | Geographical Coverage | Pricing | Easy to Use? |
|---|---|---|---|---|
| Nexmo API | Send and receive bulk SMS, private SMS, notifications, phone number verification | Global | Free inbound SMS and $0.0069 per outbound SMS (U.S.) | Yes |
| The TeleSign Score API | Provides a score of 0 to 1,000 for identifying fraudulent phone numbers | Global | Free and varying paid plans from $25 to $500 per month | Yes |
| The TeleSign SMS API | Delivery notifications, reminders, one-time passwords, two-way private SMS, two-factor authentication | Global | Free and varying paid plans from $10 to $250 per month | Yes |
| The Twilio SMS API | Sending short codes, smart content handling, text message delivery intelligence | Global | Varying paid plans from $10 to $250 per month | Yes |
| Twilio Lookup API | Get information about phone numbers, point out local-friendly phone number formats, recognize caller names. | Global | Pay-per-use pricing of $0.005 or $0.01 per request | Yes |
| Twilio Verify Phone Number API | Request a verification code to be sent to a user via SMS or voice | Global | Varying paid plans from $10 to $200 per month | Yes |
| SMSly – SMS to INDIA API | Get OTP SMS delivery services, secured SMS routes, priority SMS gateway routes, live delivery reports | India only | Free and varying paid plans from $25.99 to $189.99 per month | Yes |
| MessageBird SMS Gateway API | Send and receive text messages, verify message delivery status, lookup for invalid phone numbers | Global | Free | Yes |
| Octopush SMS API | Delivery reports, 2-way SMS, 2-factor authentication, push SMS, scheduled SMS | Global | Free | Yes |
| FreeSMS8 API | Send unlimited text messages, group SMS, classified messages, scheduled messages | India Only | Free | Yes |