question

I've removed the previous answer to prevent any confusion on this.

We currently process over 20K requests per second, and that continues to grow as more titles launch with our service (so, if you're reading this after November 2018, you can expect that number has grown). So 7K requests at the same time, with each coming from a different client, would not be an issue at all, as long as those calls are the result of actual player usage.

Put another way, and as the previous response pointed out, normal gameplay by real-world players is going to be spread out over time by its nature, so it's extremely unlikely that any significant percentage of your players would ask for their leaderboard at the same time.

Now that said, the resources dedicated to processing for calls against your title scales with usage, but that's based upon your overall usage at any given time. So, if your game adds 100K players in a day, no worries - the service will scale to that. But if you were to use a timer in your game so that every attached client were to send a request at the exact same time, that would be a problem, as it wouldn't match normal usage patterns. For completeness, the one case where you could see a massive spike in calls in normal gameplay would be if you launch a highly anticipated title or do a massive user acquisition campaign (think 250K or more users in a day). For anyone running a title at that scale, the key would be to communicate any upcoming dates like that with us, so that we can pre-scale extra servers to support it (and so, not have any issues).

Regardless of the number of users you will have, the Essentials (free) tier will work fine - there's no limit on the number of users. Limits (both to protect the service and keep costs low enough for us to be able to have a free tier and keep the paid tier costs down) are around the total amount of resources available to the title (data, statistics, etc.) and the rate at which API calls can be made on a per-client basis. The paid tiers provide higher limits, which are important if you want to run a LiveOps campaign in your title (which is critical to professional titles these days), as well as private support options and a Service Level Agreement (SLA).