Prevent fake sign-ups. Before they reach your list.
Bots, throwaway addresses, second accounts and other people’s addresses get in through any form that accepts any input. With Sendity, a sign-up only counts once the person has sent a message from their own WhatsApp account or inbox. You only get contacts that exist and belong to the person who signed up.
- No form that accepts anything
- One verified contact per sign-up
- No outbound SMS for bots to trigger
New sign-ups today
What a form accepts (example)
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xJqLmPzR kd83v@inbox.example 02:51
Bot Form filled in 0.8 seconds.
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Tom K. tom.k+3@gmail.example 09:14
Duplicate Third alias of the same inbox.
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Max Muster max@wegwerf.example 09:20
Throwaway Inbox deleted after ten minutes.
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Sabine Kraus sabine.kraus@gmial.example 11:02
Typo Real person, unreachable address.
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Peter Schmidt p.schmidt@gmx.example 14:05
Real One in five.
Sign-ups by message. No form, no code.
Sendity is a sign-up widget for your website. Instead of filling in a form, your visitors send one short message via WhatsApp or email. Sendity checks who it came from and hands your site the name and the confirmed phone number or email address.
See how Sendity works →-
One message instead of a form Visitors tap send in WhatsApp or their email app. Nothing to type, no confirmation email to click.
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Confirmed by the message itself The contact comes from the sender of the message, so typos and made-up addresses never reach your list.
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Pay per confirmed contact Start with 1,000 free credits, no credit card. After that, prepaid packages with no subscription.
Wherever a sign-up is worth something, a prize, a free trial, a voucher or a seat, someone tries to get it more than once or without giving a real contact.
Bots and scripts
Automated sign-ups fill forms in seconds, often with made-up or stolen addresses. CAPTCHAs slow down real people, and CAPTCHA-solving services get through anyway.
Throwaway addresses and duplicate accounts
Anyone who wants a second trial credit, a second voucher or a second chance to win creates aliases, throwaway inboxes or second accounts. Every one of those addresses is formally valid.
Other people’s and mistyped contacts
A form accepts any address, including someone else’s. That person receives emails they never asked for, and you get a contact that never answers. A typo has the same effect without any bad intent.
SMS pumping
If you verify with SMS codes, bots get a lever: they enter premium-rate numbers and let your form trigger expensive SMS. The bill arrives before anyone notices the fake sign-ups.
The approach: send first, then count
With Sendity, visitors send a prepared message with a short-lived code. Per campaign you verify either phone numbers, via WhatsApp by default, or email addresses, by the DKIM signature of the email. A sign-up only counts once code and sender match. WhatsApp numbers are much harder to multiply than email addresses, so choose phone numbers when one sign-up per person matters most.
Where the limit is
A verified contact shows that someone controlled that account at that moment, not who they are. A person with several real numbers can sign up several times. Your application decides what a verified contact unlocks, and it can count each one only once.
Show, send, count.
The same three steps for a giveaway, a webinar, a waitlist or a free trial.
Your page shows a code
Where the form was: as a QR code on a computer, as a button on a phone.
The visitor sends it
By WhatsApp or email, from their own account. Nothing to type.
Only verified sign-ups count
Your backend checks the signed result and accepts the sign-up. A contact that is already on your list stands out at once.
CAPTCHA and confirmation link or a sent message?
What each approach lets through.
| Aspect | Form with CAPTCHA and confirmation | With Sendity |
|---|---|---|
| Bots | Slowed down, solving services get through | Count only with a message from a real account |
| Throwaway addresses | Accepted, blocklists lag behind | Phone campaigns need a WhatsApp number instead |
| Other people’s contacts | Anyone can enter anyone’s address | Only the sender’s own contact |
| SMS costs | SMS codes can be pumped | No outbound SMS |
| When it is checked | Later, by confirmation email | In the same step, on your page |
Real contacts, fair results.
What changes when every sign-up is tied to a verified contact.
Clean lists
No bots, no typos, no strangers’ addresses. Your messages reach the people who signed up.
One reward per person
Entries, trial credits and vouchers are tied to a verified number, so duplicates stand out.
Predictable costs
You pay per verified contact. Attempts that do not verify cost nothing.
Where fake sign-ups cost you.
Live on your page in minutes.
Sendity runs as a compact widget on your page. Pick the path that fits your website.
Questions about fake sign-ups.
Isn’t a CAPTCHA enough?
A CAPTCHA tells humans from machines, nothing more. It lets throwaway addresses, second accounts and other people’s addresses through, and solving services get past it. Sendity checks that the contact belongs to the sender.
Phone number or email: which protects better?
For one entry or one reward per person, phone numbers via WhatsApp, because they are much harder to multiply. Email addresses fit newsletters and B2B sign-ups. You choose one per campaign.
Do my visitors need WhatsApp?
Not for email campaigns. Phone numbers are verified via WhatsApp by default; you can allow SMS as a fallback, which is less secure.
What does it cost?
You start with 1,000 free credits. A verified email address uses 1 credit, a verified phone number 4 credits. Attempts that do not verify cost nothing.
Keep reading.
Count your next sign-up only when it is real.
Try the live demo on your phone. It takes ten seconds.