Pro feature
Prove your ads actually played.
Proof of Play gives advertisers evidence that a post was on screen — how many times, for how long, at what hours — as a PDF for any day, week or month. Every number is measured on the device, cross-checked independently and timestamped by a third party, so nobody, including us, can quietly rewrite it.
Confidence grade A
Device, expected schedule and independent timestamp all agree.
1,204
Plays
39s
Avg time on screen
3
Screens
By day
Sample report — open SLX Verify for a live one.
How it works
Three independent layers. Each one checkable.
Numbers no single party can silently edit.
The screen is the witness
Every item is recorded on the device with its measured on-screen time, not the time it was scheduled for. Each record is cryptographically chained to the one before it, and batches are signed with a key generated in the device's secure key store, which never leaves the box. Altering or injecting history, even with full access to our database, breaks the chain.
Cross-examined, independently
Our servers verify every chain and signature on arrival. Each night, a job checks every device's report against what it doesn't control: its uptime heartbeats and the playlist it should have run. Reports that don't add up are graded down, never hidden; a post that should have played but didn't is flagged as a shortfall.
Timestamped by a third party
Every night, a cryptographic fingerprint of each screen's day is timestamped by two independent RFC-3161 Time Stamping Authorities (freetsa.org and DigiCert), outside bodies attesting that the data existed by that date. Nobody, including us, can back-date, amend or fabricate a report afterwards, and anyone holding a report can download its raw RFC-3161 tokens from the report’s verify page and check them independently with standard tools (openssl).
Transparency
Honest by design
Most signage tells you what it meant to show. We tell you what actually happened — including when it wasn't perfect.
Verified vs. presented
Where the panel reports its state, we can tell whether the TV was actually receiving a signal over HDMI. Screen-time we can vouch for is shown as verified; time we can't — including screens whose panel doesn't report — is disclosed separately, never quietly counted as proof.
A grade on every report
Each report carries a prominent A–D confidence grade based on how well the independent checks agree. We show it even when it's a C.
Gaps, not invented numbers
A device-dark day shows as a gap. An interrupted play counts only its real seconds. Anomalies grade the day down.
What it proves — and what it doesn't
Proof of Play proves your content was played on the screen. It does not prove a person watched it: a covered screen or an empty room looks the same as a busy one. It is not audience measurement — there are no impressions, no demographics, and no tracking of people. The Smart Box has no camera and no microphone; those permissions don't exist on it, they aren't merely switched off.
SLX Verify
Anyone can check it. No login. No trust required.
Every report carries a unique digest and a QR code linking to a public verification page. Anyone holding it can confirm it is genuine and unaltered, and see its grade and third-party timestamps, without trusting whoever handed them the PDF.
Report verified
Device signature & timestamp both check out
Plays
1,204
Verified screen-time
13h 6m
Range
Last 30 days
Timestamped
RFC 3161
Sample — open SLX Verify for a live report.
For advertisers and media buyers
Pay for screen time you can check.
What you get
A PDF report for any day, week or month: how many times your ad played, for how long, at what hours, on which screens.
A confidence grade from A to D, based on how well independent checks agree. And a QR code to SLX Verify, so your client can confirm the report is genuine without trusting whoever sent it.
Sample report
What it doesn’t claim
Proof of Play proves the ad played on the screen. It does not count viewers: a covered screen or an empty room looks the same as a busy one. There are no impressions, no demographics and no tracking of people. The Smart Box has no camera or microphone.
For screen owners
How to sell screen time.
01
Set your rateDecide the price per week or month. You collect payment directly from the advertiser.02
Give posting accessAdd the advertiser to your board so they can post their ad, or post it for them.03
Share the reportSend the Proof of Play report at the end of the period. They can verify it on SLX Verify.
Questions advertisers ask
Can I see a report myself, as the advertiser?
Does it count how many people watched?
How do I know a report is genuine?
Turn your screens into provable advertising.
Included on Pro. Reports are available to the post's author and the board's admins.