> For the complete documentation index, see [llms.txt](https://docs.1kosmos.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.1kosmos.com/identity-verification/verification-methods/web-to-mobile-handoff.md).

# Web-to-Mobile Handoff

***

Most desktops and laptops don't have a camera that's good enough to capture an ID document  and most users would rather not hold their license up to a webcam anyway. 1Kosmos's **web-to-mobile handoff** lets the user start a verification on whatever device they signed up on, and seamlessly move to their phone for the capture step.

The user never has to copy a link, type a code, or find the SMS app.

### How it works

{% stepper %}
{% step %}

#### User starts on desktop

They click your "Verify your identity" CTA. Their browser opens the session URL on the desktop. 
{% endstep %}

{% step %}

#### 1Kosmos checks camera capability

The session detects the desktop browser doesn't meet the minimum camera resolution (1080×1920) — or simply isn't a camera-capable form factor.
{% endstep %}

{% step %}

#### A QR code appears

The desktop UI displays a QR code with a one-time, session-bound handoff URL.

The session is **not yet started** on the mobile side it's just an invitation to continue.
{% endstep %}

{% step %}

#### User scans the QR with their phone

The same session same `sessionId`, same flow, same expiry opens on mobile. The desktop UI updates in real time to show "Verification in progress on mobile…
{% endstep %}

{% step %}

#### User completes capture on mobile

Document scan and selfie are captured on the phone. On completion, the desktop UI advances to the result screen.
{% endstep %}
{% endstepper %}

#### When it triggers

The QR handoff is offered automatically when any of these is true:

* No camera is detected on the desktop browser.
* The desktop camera resolution is below the 1080×1920 minimum.
* The user explicitly clicks "Continue on phone" on the start screen.

If the desktop camera *is* adequate (some laptops have very good ones), the user can continue on desktop. The QR option is still shown as an opt-in alternative.

#### Session continuity guarantees

* The `sessionId`, expiry, and result are shared across desktop and mobile. There's no second session created on handoff.
* The result is delivered to **both** browser contexts. Whichever the user closes first, the other still receives the update.
* Handoff URLs are bound to a single session and become invalid after first use.

#### Edge cases

* **User abandons on mobile.** The desktop UI continues to wait until the session's `from_session_start` expiry. After that, the session moves to `abandoned`.
* **User reopens the QR after using it.** The handoff URL has already been consumed; the user is shown a "this link has expired" screen with a button to start over.
* **Two devices race the handoff.** The first successful capture wins; subsequent submissions are rejected with `session_already_terminal`.


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