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Inline OTP verification vs OTP verification
- Last Updated : August 21, 2025
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- 3 Min Read
You might already have a huge contact list in your CRM from data collected through your contact form embedded on the website. But your contact list is only as good as the quality of the leads in it. Without proper verification, your contact form could be filling up with fake names, throwaway emails, or invalid phone numbers, clogging your CRM with dead ends.
OTP verification changes that. Without the verification, you might have entries like john@example.com or 9999999999, which are useless for follow-up. By confirming every email or phone number in real time, you ensure that every contact you capture contains valid data.
Zoho Forms provides two options for verifying the authenticity of form submissions: Inline OTP Verification and OTP Verification. Both methods are designed to confirm that the provided email address or phone number is valid and belongs to the respondent, but they differ significantly in when and how this verification occurs during the submission process. Let's review how both of these spam control techniques work in detail.
What is inline OTP verification?
Inline OTP verification embeds the verification step directly into the form-filling experience, allowing respondents to receive and enter their OTP without leaving the form. This seamless approach ensures real-time validation before the user can proceed to the next step.
How it works
- The respondent opens your form and starts filling it in.
- When they reach an Email or Phone field with OTP enabled, they click a Verify button.
- They receive the OTP via the chosen method (email, SMS, or WhatsApp).
- They enter the OTP directly in the form.
- Once verified, they can continue filling out and submitting the form.
What is OTP verification?
OTP verification is a pre-access verification step. Before the respondent can even view the form, they must enter their email address or phone number and verify it via an OTP sent to that contact. They'll only be able to open the form and fill it out after after successfully completing verification.
How it works
- Respondent clicks the public URL of your form.
- OTP Verification screen appears. Before the form loads, they see a verification page asking for their email address or phone number.
- Respondent enters an email address or mobile number to receive the OTP.
- Respondent receives the OTP. The code is sent via email, SMS, or WhatsApp depending on your chosen configuration.
- Respondent enters the OTP on the verification page.
- Once the OTP is verified, form opens for the respondent to access.
Key differences at a glance
Scenario | OTP Verification | Inline OTP Verification |
When it happens | Before respondents can even view or start the form | Midway through form filling, when contact information is entered |
Best for | Exclusive or high-security forms | General forms where accuracy of contact details is important |
Primary goal | Restrict access to verified individuals only | Ensure valid email/phone without blocking form access |
User Experience | Feels like a secure “members-only” gate—only verified users get in | Feels like a quick, non-intrusive check inside the form |
Spam prevention | Stops bots and fake users before they can interact with the form | Eliminates fake contact details before form submission |
Verification channel options
No matter which OTP method you choose, you have flexible delivery channels to match your audience’s habits and your verification goals.
Perfect when email is your primary point of contact. The OTP is sent directly to the respondent’s inbox, ensuring the email address not only exists but is also actively monitored by its owner. Great for lead capture forms, newsletter subscriptions, and sign-ups where follow-up via email is essential.
SMS
An instant, mobile-first approach that verifies phone numbers through a quick text message. Works well for food delivery orders, service bookings, customer support forms, and more.
Leverage one of the world’s most widely used messaging platforms for faster, more engaging verification. Ideal for audiences that are already active on WhatsApp, which can make it a perfect choice for local businesses.
Advanced customization for every channel
- Set an expiration time for each OTP to control how long users have to complete verification. This helps balance security with user convenience.
- Fix the number of resend attempts to prevent misuse while allowing enough flexibility for genuine respondents.
- Personalize the call-to-action (e.g., "Send Code", "Get Verified", or "Confirm Access") for a more engaging experience.
- Add an extra security layer to block automated bots by pairing CAPTCHA with OTP verification.
Choosing the right verification method
Choose inline OTP verification when your priority is to ensure valid contact details without interrupting the form’s overall accessibility. It is ideal for newsletter sign-ups, free trial requests, or e-commerce order forms, where you want every email or phone number to be valid, but you don’t want to block form access for casual visitors.
