Piggyback Try the demo

Two-Feet Authentication.

Piggyback is a second factor you pass barefoot. Show your phone the foot it asks for, lift your toes when it says so, and you're in. It sits on top of the login you already have.

Try the demo Self-host it

Demo: any name, the password demo, then your feet.

Works with

Any backend, by redirect <piggyback-auth> Okta Entra ID Ping Keycloak Auth0

How it works

It runs in the phone's browser, so there's no app to install. You need a plain floor and bare feet.

  1. The scanner on a phone: a right foot inside a phone-shaped lens, the green line filling around it, and the status Hold still.

    Enroll once

    Show the top of your right foot, then your left. Each one is saved after a couple of seconds held still, then shown back so you can redo it.

  2. The hosted scan page on a phone, with the tagline Frames are checked, never recorded, above the lens and a right foot inside it.

    Show the foot it asks for

    At sign-in the server picks a foot. Piggyback compares its outline, width profile, proportions, skin texture and tone with the one you enrolled.

  3. Piggy Bank, the demo app, after sign-in: the pig points at a card that says Right foot and Toes wiggled.

    Lift your toes when asked

    Once it matches, keep your heel down and follow the prompts: toes up, down, then up again. A photo of your feet can't follow them.

Signing in on a computer

  • It shows a QR code. “Continue on your phone” holds a one-time link that expires in two minutes.
  • The phone scans it. No app to install: it opens in the browser and asks before it carries on.
  • The computer finishes by itself. Feet on the phone, sign-in on the laptop.
On a computer, the scanner's lens shows a QR code with the pig in the middle, next to the status Waiting for your phone and a Use this computer button.
The phone after scanning the code: Enroll your feet for Piggy Bank, Started on a Mac in Chrome, and a Scan my feet button.

Why feet

  • Nothing to carry

    No key fob and no code to retype. You need your phone's camera and your feet.

  • The server picks the foot

    Each sign-in asks for the left or the right foot at random, so nobody can prepare the right one in advance.

  • Photos don't pass

    The toes have to move on cue while the heel and the floor around them stay put. A photo moves as one flat picture, however it's tilted or zoomed, and a finger over the toes is caught.

  • The pig judge

    A small pig reacts to each scan. His reactions come from image texture, not your foot's size or shape, and play no part in the decision.

For developers

Keep your password or SSO. Piggyback adds the feet check, decides on the server, and gives your backend a signed, one-time result.

<!-- Drop the scanner into your own page -->
<script type="module"
  src="https://feet.example.com/sdk/piggyback.js"></script>
<piggyback-auth
  server="https://feet.example.com"
  session-token="{{ session_token }}"></piggyback-auth>

<script>
  document.querySelector("piggyback-auth")
    .addEventListener("piggyback-complete", e =>
      exchange(e.detail.code));
</script>

Keeps people on your page. Theme it with --pb-accent, --pb-bg and friends; on a computer it offers the phone handoff by itself.

Integration guide API reference Identity platforms

Frames are checked, never recorded.

Looked at, then dropped

Frames are analysed in memory and thrown away. Only measurements are kept: numbers that describe a foot, not a picture of one.

Encrypted at rest

Foot templates are encrypted with AES-256-GCM and bound to the app and the user they belong to.

On your own server

You run it, you hold the keys. Every decision is made there, and match scores never reach the browser.

Gone on request

One call, DELETE /v1/users/:id, removes someone's feet for good, when they close their account or want to enroll again.

Limits

Piggyback is a prototype. Matching was tuned on drawn sample feet, not real ones, and a video of your toes played back in time with the prompts could pass the liveness check. Use it alongside a passkey or an authenticator app, not instead of one.

Foot templates are biometric data: get consent, honour deletion and check the law where your users are. Before production

Questions

Does it work with socks?

No. It's looking for skin and toes, so socks off, on a plain floor. A floor lighter or darker than your skin and good light help most.

Which foot do I show?

Whichever one it asks for. At sign-in the server picks a foot, and the lens shows its outline so you know which one.

Can someone just use a photo of my feet?

No. After the match, the scanner asks for toes up, down and up again, and checks that only the toes changed. A photo fails however it's moved. A video played back in time with the prompts could pass, which is why Piggyback is a second factor next to your password, not the only one.

My laptop's camera can't see my feet.

On a computer it shows a QR code instead. Scan it with your phone, show your feet there, and the computer carries on by itself.

What exactly gets stored?

Measurements, not pictures: a few hundred numbers per frame, a couple of frames per foot, encrypted and tied to the app and the user. The frames themselves are analysed in memory and dropped.

What if I can't, or would rather not, use my feet?

Apps using Piggyback should always keep another way in, like a passkey or an authenticator app. The hosted page can offer “Use another sign-in method”.

Try it

Sign in to Piggy Bank, the demo app, with any name and the password demo. Then show it your feet.

Try the demo Self-host it
The Piggyback pig, winking and pointing at the demo button.