Secure verification with SMS OTP codes
Protect logins, sign-ups and transactions with one-time codes sent by SMS. High delivery speed thanks to direct Belgian routing — 98% of codes are delivered within 3 minutes. SMSBOX generates and validates the code for you — verification is free.
Applications
OTP via SMS is the standard for two-factor authentication and sensitive actions. No extra app required — it works on every phone.
Two-factor authentication (2FA)
A second security layer at login, on top of the password.
Account creation
Verify phone numbers when new users register.
Transaction verification
Confirm payments, transfers and critical actions.
Password reset
Recover a password securely, without vulnerable e-mail flows.
How does it work?
Request a code
Your application calls POST /v2/otp/send with the user's phone number. SMSBOX generates and sends the code.
The user enters the code
The user receives the SMS and enters the code on your website or in your application.
Verify the code
You call GET /v2/otp/verify with the code entered. Verification is completely free.
Integrate in minutes
Two endpoints: one for sending and one for verifying. SMSBOX generates and stores the code itself — you do not need to set up any code management of your own. Includes the official PHP SDK and code samples for Python, Node.js, C# and PowerShell.
POST https://core.smsbox.be/api/v2/otp/send X-Api-Key: YOUR_API_KEY Content-Type: application/json { "number": "32496123456" } GET https://core.smsbox.be/api/v2/otp/verify?otp=482913 X-Api-Key: YOUR_API_KEY SMS OTP versus the alternatives
SMS OTP
- Works on every phone
- No app installation needed
- High open rate (98%)
- Ready to use immediately
- Works offline (no wi-fi)
Authenticator app
- No cost per code
- Requires an app installation
- Setup hurdle for users
- Lost when switching phones
- Not suited to one-off flows
E-mail OTP
- No cost per code
- Slow delivery (spam filters)
- Low open rate (~20%)
- Vulnerable to phishing
- No channel separate from the password
