Engineer on the Tiles team here. That is not exactly true. We do not obtain the list if top sites. What we receive is the list of non-history tiles that has b

Engineer on the Tiles team here. That is not exactly true. We do not obtain the list if top sites. What we receive is the list of non-history tiles that has been shown to the user. i.e. if the Tile is a "known" tile, we'll capture the impression, or click. If it's not, we will receive an almost empty placeholder for that site, barring for the frecency score. This is along our philosophy of least amount of actionable data collected. For instance, if a user had one Tile we know about at the 5th position, we'd get something like: {"tiles":[{"score":42},{"score":32},{"score":22},{"score":8},{"score":3},{"id": 500, "score":2},{}],"locale":"ja","view":6} The id allows us to count impressions, clicks and whatnot for that Tile, the "score" allows us to gauge frecency, i.e. how important is the tile for the user, together with the position in the array. It's not nothing, but it's not your top sites. Edit: formatting Source code available at: https://github.com/mozilla/onyx https://github.com/mozilla/onyx https://github.com/mozilla/splice https://github.com/mozilla/splice https://github.com/mozilla/infernyx https://github.com/mozilla/infernyx