> ## Documentation Index
> Fetch the complete documentation index at: https://docs.verifyyou.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Gate a signup

There's no limit to how many emails or devices a human can own, but they cannot replace their face. Here's how we limit each person to one account with HumanCheck:

1. **A live person has to be there.** A photo held up to the lens, a recorded video, or a script never gets past this one.
2. **The first account through owns that face.** The scan becomes a face vector, a numerical representation of the face's geometry. Whoever signed up first keeps their account, and nothing here touches them again.
3. **A second signup with that face is recognized as the same person**, whatever email or login they use this time. That holds across your other checks too.
4. **You decide what happens to the second account.** Refuse it, and they are told an account already exists. Or let it through and have the person flagged for your team. The setting is **On collision**.
5. **Ask for a phone or an email.** Set that way, the same person is recognized wherever they sign up from, so a new phone changes nothing. Left anonymous, recognition stays with the device they used, which suits a one-off check and not a signup.

A gate only covers new signups. For the accounts you already have, see [Userbase healthcheck](/docs/use-cases/userbase-fraud-audit).

## How you start

1. Create a verification and pick the **Signup Gate** preset.
2. Set **Identity** to *Linked by guest*, which is the phone or email in point five.
3. Set **Verification limit** to *Once per lifetime*, so one person gets one account, and **On collision** to *Block*.
4. Paste the no-code link into your signup, or use the SDK and [confirm the result on your server](/v3/dev/integrating/handling-results).
5. Run it on [test keys](/v3/dev/spec/server-api/authentication) first. The simulator behaves like the real check, and the test people it creates stay separate from your live records.

## Next steps

<CardGroup cols={2}>
  <Card title="Configuration" icon="sliders" href="/docs/verifications/configuration">
    Set what the check does, including denials.
  </Card>

  <Card title="Integration" icon="code" href="/docs/verifications/integration">
    The no-code link, or the SDK.
  </Card>

  <Card title="Reading Activity" icon="wave-pulse" href="/docs/activity/reading-activity">
    Who reached the gate, and who was refused.
  </Card>

  <Card title="Guests and members" icon="users" href="/docs/how-it-works/guests-and-members">
    How recognition carries across your checks.
  </Card>
</CardGroup>