LoL Skins Viewer

Out of the many things you can purchase with Riot Points in League of Legends, champion skins are definitely the most sought-after. However, it can be difficult to keep track of the ones you already own, which is where this nifty Electron-based app comes into play.
LoL Skins Viewer is an open-source application that connects to your LoL account and lists all the skins you own, as well as those you have not yet purchased. Additionally, it can estimate the total RP value of your owned skins.

Works with the updated League of Legends client

The app does not ask for your account info, as it simply interfaces with the LoL client to extract the necessary data. Naturally, this means they both need to be open at the same time, and you will only be able to view your skins if you are logged in.
Another thing worth noting is that LoL Skins Viewer only works with the updated version of the League of Legends client. The redesigned GUI is currently in open beta, so you easily switch to it at any time.

Keep track of your owned and unowned LoL skins

Once connected to your LoL account, the application displays all the champion skins you own, and you can also view an estimation of their RP value to get an idea of how much you have spent.
Not only that, but the app can also list every available skin, as well as unowned ones. These can be sorted alphabetically, by mastery or RP value, and a simple search function is included, which can also be used to filter skins based on champion.

Intuitive app that sports a familiar GUI

Provided the League of Legends client is already running, LoL Skins Viewer should detect it and extract the necessary info automatically. However, you can also locate the LoL directory manually if needed.
The UI scale can be changed from the Settings panel, and there is also an optional low spec mode, which removes sorting animations, for those using older PCs. The visual design is clearly inspired by the updated LoL client, which users should already be familiar with.
LoL Skins Viewer is, in short, a great app for League of Legends players who have a hard time keeping track of the champion skins they own and those they are interested in purchasing. It features a clean UI, which looks very similar to the updated LoL client, and it is very easy to use.