Why using SMS or email verification?

Verify & qualify users

One-time passwords help you check users’ identity and get qualified leads. Make sure you acquire users that will convert.

Reinforce security

Data is the new bacon. Protect your users and your business from account takeovers or data theft.

Avoid fraud & block spam

Clean up your database by blocking spam accounts or bots. Avoid fraudulent accounts and optimize your metrics.

Try a working demo

This is a signup demo with email verification that connects Arengu with an external API.

1. Email inline validations
The form automatically checks if the email belongs to a domain without an MX record configuration, and checks if the user already exists on the database. If this email exists, it tries to log it in the platform, otherwise it sends an OTP.
2. Send the OTP

After credentials submission, and if they are correct, it generates and sends an OTP to the user's email using MailJet, but you can use SendGrid, Twilio or any service you can connect with via API instead.

3. Verify identity and sign up

If the OTP code is also correct, it will sign the user up into the platform, set authentication cookies and display a success message. It's easy to redirect users to your destination page too.

3. Login

If email is already registered and provided password matches, it will log in into the platform, set authentication cookies and display a success message. It's easy to redirect users to your destination page too.

Developer friendly

Save development time, embed anywhere with a line of code.

Stack agnostic

Embed it, with a simple line of code, in most popular CMS platforms, landing page builders and development frameworks.

Integrations with any API

Quick integration with almost every API and common ID providers (Auth0, Okta...), adding flexibility to forms and logics.

Save time and resources

We help teams with repetitive and complex actions, building - easy to edit, maintain and scale - templates.


Frequently asked questions about OTPs and two-factor authentication.

Arengu generates a temporal code, consisting on aleatory characters or numbers. This code is associated with a reference (usually an email account or a phone number). This code is temporal and it exists only until the user validates their identity by entering the code where needed. One-time passwords can be sent through different means: via email, via SMS or even via phone calls. Depending on your business and the user’s preferences, you can choose to send one-time passwords to the user’s email or to the user’s phone.

OTP stands for ‘One-Time Password’. One-time passwords are a series of numbers or characters, generated automatically and sent to a certain user so they can verify their identity. One-time passwords are meant to verify the user’s identity, especially in sign-up, login or transaction processes.

If you manage a lead acquisition site or if your business is based on a sign-up model, including an OTP verification system is a great idea to improve security, avoid fraud and get better, qualified leads.

OTP helps you confirm the user’s identity. Even though OTPs add one more step to a sign-up or login process, it also adds a considerable degree of safety both to your business and to your customers. SMS or email confirmation blocks bots and fraudulent accounts. Thanks to SMS and email verification, you can be sure you get real users -instead of bots or spam accounts- and security is reinforced.

Sure! Passwordless forms are an excellent way to onboard users without any friction. Still, at some point you will need to implement an authentication factor, and that’s where OTPs enter the scene. Sending an OTP to the user’s email or phone number ensures a reliable degree of security, plus identity verification. The frictionless process won’t be damaged, since the user can verify their identity later on.

Two-factor authentication (also known as two-step authentication) is a type of identity verification process, where the user has to prove their identity in two different steps. Given the increasing number of methods for hacking users’ identity, multi-factor authentication is a frequent method used in sign-up and login processes.

Generally speaking, passwords are the main authentication method, and they can be complemented with a second step to add an extra layer of security. OTPs can work as the second step in a two-factor authentication.

Yes! With Arengu, you can send an OTP with some of the main providers, such as Twilio, MessageBird -for SMS- or Mailjet -for emails-, among many others. But, if you want, you can also use the ‘HTTP request’ action and build it yourself to use any other provider you need. You can tailor the whole flow to your needs.

Of course! If you want to send an OTP email with a branded style, or simply if you want to personalize your message, you can do so using Arengu. Just select your email or SMS provider and select the template you want to use.

If you don’t have a template or if your provider doesn’t support templates, you can also send the email with HTML content in Arengu’s editor.

Yes. Just add the ‘Verify email address’ action to your flow and select as many options as you want. You can block free email providers, temporal emails or email account aliases. You can also add any email account to a blacklist and a whitelist to personalize your flow as much as you need.

Email and SMS verification are one of the best authentication methods there are. Both with SMS or email verification, the friction added to the login or signup process is minimal. Even though this adds one more step for the user, the simplicity of the verification process makes it an optimal method to add security without damaging conversion rates. But, which mean is better? Even though this depends highly on your business and your audience preferences, we offer you some highlights on each method.

Pros of OTP email verification

Email verification is frequently used, for several reasons. On one side, users are more likely to share their email address than their phone numbers. Since email addresses are already mandatory in a signup process, users may be less reluctant to verify their identity with this mean.

Another pro of email authentication is its price. Sending emails is way cheaper than sending SMS. If your business is on a budget, email authentication may seem like a better option.

Cons of OTP email verification

On the not-so-bright-side of email verification, we find security. Emails may suffer from phishing, viruses and so on. If the user account is hacked, the verification process will be affected.

Pros of OTP SMS verification

SMS authentication usually minimizes friction. Generally -especially in a mobile-first context-, the user doesn’t even have to leave the interface to see the OTP and enter it. Quick for your business, painless for the user.

Security is another bright side of SMS verification. Faking a phone number is much harder than faking an email account. User’s identity has one more level of ‘realness’ compared to email verification.

Cons of OTP SMS verification

Sending SMS is more expensive than sending an email. Plus, some users may hesitate before entering their phone numbers. This may affect your conversion rates.