The WordPress Updates API is pretty much a mystery to many developers for many reasons, not least of which is the fact that there is no documentation for it. For plugins hosted in the WordPress Plugin Directory and themes hosted in the WordPress Theme Directory (and core itself), the API “just works”. Plugins and themes hosted externally (such as premium plugins/themes) need to hook into the API and ensure the proper information is populated in the proper site transients so that core can offer updates for those externally hosted plugins/themes. What site transients are those: update_plugins update_themes (and of course, update_core for core updates). This plugin attempts to demystify the Updates API by allowing you to inspect: how the API is queried by core what the API returns in respose to a query what’s in the site transients core uses when offering updates to admin users (whether manual or auto-updates) At this point, this plugin is very preliminary (it is version 0.1.1 after all), but I’m releasing it in it’s current state because of the new Auto-updates UI in WordPress 5.5.0. While many externally hosted plugins/themes have been hooking into API for years, the new auto-updates UI has certain requirements for how the site transients are populated and not all externally hosted plugins/themes have populated them such that the new UI will work properly (see Recommended usage of the Updates API to support the auto-updates UI for Plugins and Themes in WordPress 5.5). My hope is that by providing an easy way for developers to inspect the API queries/responses and the site transients core populates from them, they will more easily be able to update their code so that the new UI works properly for them. In future versions, I plan to add many other features, as well as more extensive on-screen help of an “educational” nature.