Skip to main content

Age Verification

You can verify someone's age without learning their date of birth nor their actual age.

These examples use the @zkpassport/ui verify button and verify the proofs on your server. The query you build is what matters — see Basic Usage for how to use the SDK directly instead.

Verify if the user is over 18 years old​

You will not learn their date of birth nor their actual age, only that they are 18+.

import { VerifyWithZKPassport } from "@zkpassport/ui/react-button";

<VerifyWithZKPassport
  purpose="Prove you are 18+ years old"
  service={{ scope: "adult" }}
  query={{ age: { min: 18 } }}
  onSuccess={async ({ proofs, result }) => {
    // Send the proofs to your server to verify them
    const response = await fetch("/api/verify", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ proofs, result }),
    });
    return (await response.json()).verified;
  }}
/>;

On your server, recreate the query and verify the proofs (see Quick Start):

const { query } = zkPassport.createQuery().gte("age", 18).done();
const { verified } = await zkPassport.verify({
  proofs,
  originalQuery: query,
  queryResult: result,
  scope: "adult",
});

if (verified) {
  const isOver18 = result.age.gte.result;
  console.log("User is 18+ years old", isOver18);
} else {
  console.log("Verification failed");
}

Verify if the user is between 18 and 25 years old​

Set both bounds (they are inclusive). Only the query and result handling change — drop them into the same button and server code as above.

const query = { age: { min: 18, max: 25 } };
// On your server: .gte("age", 18).lte("age", 25)

// Once verify() succeeds
const isBetween18And25 = result.age.gte.result && result.age.lte.result;
console.log("User is between 18 and 25 years old", isBetween18And25);
note

The SDK also has a range operator, but the button's min/max always map to gte/lte — recreate them with those.