Here is a list of lite versions of famous Android apps, designed for low data usage and made for not-so-new smartphones.
Youtube Go is a small version of the YouTube app, designed for limited data or a slow connection. It offers the option to choose the quality level of the video, share it and even to save it for offline viewing. It's 9 MB in size and requires Android 4.1 or higher.
Maps Go is a web-based version of Google Maps designed for low RAM devices and slow connections, even 2G.
The app on the Google Play Store is currently available only for devices with Android Oreo (Go Edition), but since it's a Progressive Web App (PWA), i.e. an optimized website that simulates a mobile app, you can use it from any device by visiting the link in the Official Website button.
The Facebook app is recognized as the app with the greatest impact on your phone: it drains battery life, it makes your phone slow and consumes a lot of data and internal storage.
So why not try Facebook Lite, its official reduced version, as replacement?
It offers all the important functions without its many bloated features in just 1.6MB, compared to the 65MB of the main app.
Messenger Lite is a lightweight version of Facebook Messenger that allows you to chat with your Facebook friends, make voice calls, send photos, videos and links. It lacks a lot of features, like video chat, chat heads and SMS integration, but it's just 10 MB in size and supports Android 2.3 and above.
Twitter Lite is a mobile optimized version of Twitter designed for low data usage. Like Maps Go, it's a Progressive Web App and needs just 3MB of space. It offers almost everything the standard website has, including push notifications. The app requires Android 5.0 and above.
With Skype Lite, Microsoft managed to include all the features of Skype (except animated emojis) in a 13 MB Android app. Unfortunately, in order to use less data, you will get a lower quality for your video calls, but this is what to expect from a lite application. The app requires Android 4.0.3 or higher.
LinkedIn Lite is a data optimized version of LinkedIn , which reduces by 80% the data usage. It includes news feed, jobs, profiles and networks in addition to messages, notifications and search function. The app is only 1 MB in size and requires Android 4.4 or higher.