What we collect

Observed daily from 2026-08-12 to 2026-08-25. Counts recomputed on 2026-08-25.

What we measure, and why it is not available anywhere else

A studio certifies several builds of the same slot and publishes the list. That part is open. Which of those builds a given casino installed is published by nobody: not the studio, not the operator, not the regulator. It is visible only in the lobby itself, and only on the day you look.

So we look every day, in every market on the list. One day tells you what is installed right now. A run of days tells you when it changed, and that is the part nobody can back-fill. History before the day you started collecting does not exist anywhere to be bought.

Every number on this page is recomputed from the snapshots themselves. None of them are typed in by hand.

What the shelves publish besides return-to-player

Return-to-player is a narrow good. Only some suppliers encode a build version, only some operators print a number, and every figure has to be proven before it can be used.

The shelf itself is wider and harder to argue with. Operators publish which studio made each game, which shelf it sits on, whether it feeds a jackpot — and, on some lobbies, the date the game went live on that shelf. We checked that this date describes the shelf rather than the game: lobbies running on shared technology report it identically, while independent ones disagree on roughly every second title.

That matters because it is history we did not have to wait for. Nine days of our own observation sit next to nine years the lobbies published themselves.

Lobby-published history reaches back to 2017-02-07

The date is what the operator states, not what we measured. We have shown it varies between lobbies; we have not shown it is accurate. That check becomes possible only once our own record is long enough to compare against.

Where companies disagree

In the lobbies read on 2026-08-25, 318 games carry different certified returns at different companies in the same market. Two lobbies inside one company do not count, that is a deployment detail. A disagreement is two different companies holding two different builds of the same game.

Markets shown here are the ones where a disagreement was found on the last observed day. The full collection covers 15 markets.

Both directions are printed on purpose. A company running the higher build in one market runs the lower one in another, and the reverse holds too. This describes how the market is configured. It is not an accusation against anyone in the table.

Published work you can cite

• Slot RTP versions 2026

  The frozen dataset behind the studio side of this work: which games ship in more than one certified version. Carries a DOI and an open licence.

• Methodology

  Sources, snapshot chain, confidence level per field. Read this before citing anything we publish.

• Public API

  JSON endpoints over the published registry. No key required.