WhatsApp OTP Service Provider with Autofill and SMS Fallback

What a WhatsApp OTP service provider sets up for you

WhatsApp OTP runs on the WhatsApp Business API, which needs a verified business, a phone number registered on the API and templates approved by Meta. As a Meta Tech Provider, we handle the account setup, help you create the authentication template and give you API access to send codes. Your server still generates and checks each code. We deliver it and give you the delivery status, so your app knows when to try SMS instead.

Our WhatsApp plans list the authentication rate clearly: ₹0.16 per OTP on Starter at ₹999 a month, ₹0.14 on Growth at ₹2,499 a month and ₹0.12 on Pro at ₹4,999 a month, with a one-time setup fee of ₹2,999, ₹4,999 or ₹9,999. Charges apply only when Meta confirms delivery. Meta has priced WhatsApp per message since 1 July 2025, so each OTP is billed on its own.

Meta's rules for authentication templates

Meta does not let you write your own OTP text. The body is fixed as "<code> is your verification code." You can add two optional lines: "For your security, do not share this code." and an expiry warning set anywhere from 1 to 90 minutes. The code can be up to 15 characters long. URLs, media and emojis are not allowed, and WhatsApp disables forwarding of authentication messages, which makes phishing with a forwarded code harder.

Every authentication template carries a button. Copy code works on any phone. One-tap autofill opens your Android app and passes the code to it, and zero-tap delivers the code to the app without any tap. Both need your app's package name, its signing key hash and a handshake from the app before the message is sent. If those checks fail, or the user is not on Android, WhatsApp falls back to a simpler button, usually copy code.

WhatsApp OTP price compared with SMS OTP

Per message, WhatsApp can look cheaper. An SMS OTP costs ₹0.20 on our Starter plan or ₹0.15 on Business, plus 18% GST, with no monthly fee. A WhatsApp OTP costs ₹0.12 to ₹0.16, but the plan carries a monthly fee. At 20,000 OTPs a month, SMS on Business costs ₹3,000 plus GST, while WhatsApp Starter costs ₹999 plus ₹3,200 in message charges, or ₹4,199 in total.

So if you only need OTPs, SMS is usually the cheaper channel on our price list. WhatsApp OTP pays off when you already run a WhatsApp plan for support or marketing, when one-tap autofill helps more users finish sign-up, or when SMS pumping costs worry you. If your company is based outside India, Meta may charge its higher authentication-international rate on Indian numbers, so ask us to check before you compare.

• SMS OTP: ₹0.20 or ₹0.15 per delivered SMS plus GST, no monthly fee
• WhatsApp OTP: ₹0.16, ₹0.14 or ₹0.12 per delivered message, plus the plan fee
• Both channels: charged only on delivery
• SMS needs a DLT template; WhatsApp needs a Meta-approved authentication template

Designing SMS fallback for WhatsApp OTP

A WhatsApp OTP reaches only a phone that has WhatsApp on that number and an internet connection at that moment. SMS reaches any mobile with network signal, including feature phones and phones with mobile data switched off. Meta itself advises checking that WhatsApp is installed before offering it, confirming the user's WhatsApp number and offering more than one channel. So treat WhatsApp as the first try and SMS as the safety net.

A simple flow works well. Send the WhatsApp OTP and wait for the delivered status. If the API returns an error, or no delivery arrives within about 20 to 30 seconds, send the same code by SMS on your DLT-approved -T template. Set the WhatsApp message time-to-live close to your code expiry. Meta allows 30 seconds to 15 minutes for authentication templates and drops messages it cannot deliver in that time.

• Let users choose "Get code on WhatsApp", since Meta requires opt-in before you message them
• Use one code per login attempt, valid on both channels
• Log which channel delivered each code
• Offer resend by SMS after a short wait

Stopping OTP pumping and account takeover

SMS pumping is a fraud where bots request OTPs to numbers that fraudsters control, so they can earn a share of the termination fees paid to deliver each SMS. A WhatsApp message travels through Meta's platform instead of a mobile operator's SMS network, so that payout does not exist in the same way. Bots can still trigger codes you pay for, though, and your SMS fallback stays exposed, so the usual limits still matter.

Limit OTP requests per number, per device and per IP address each hour. Put a captcha on public sign-up forms. Do not fall back to SMS for country codes your app does not serve, and watch for sudden spikes from unusual number series. Meta also warns that phone numbers get recycled, so for sensitive accounts tie the user to the WhatsApp identity seen at first sign-up, and do not treat the number alone as proof of identity.