1) PubgUtils
ᴛʜɪs ɪs ᴀ ᴀɴᴅʀᴏɪᴅ ʟɪʙʀᴀʀʏ (.ᴀʀʀ) ғᴏʀ ᴍᴀᴋɪɴɢ ᴘᴜʙɢ ᴄʜᴇᴀᴛs (ʜᴀᴄᴋs) ɪɴ ᴍᴏʀᴇ ᴘʀᴏғᴇssɪᴏɴᴀʟ & ᴇᴀsʏ ᴡᴀʏ. ᴛʜɪs ʟɪʙʀᴀʀʏ ᴄᴏɴᴛᴀɪɴs ʙᴀsɪᴄ ғɪʟᴇs ᴏᴘᴇʀᴀᴛɪᴏɴs ᴡʜɪᴄʜ ɪs ᴜsᴇᴅ ɪɴ ᴍᴀᴋɪɴɢ ᴄʜᴇᴀᴛs. ᴛʜɪs ʟɪʙʀᴀʀʏ ᴏɴʟʏ ᴍᴀᴋᴇs ʏᴏᴜʀ ᴡᴏʀᴋ ᴇᴀsʏ, ɪᴛ ᴅᴏ ɴᴏᴛ ᴘʀᴏᴠɪᴅᴇ ᴀɴʏ ᴛʏᴘᴇ ᴏғ ᴍᴏᴅ ғɪʟᴇs ᴏʀ ᴀɴʏ ᴋɪɴᴅ ᴏғ ᴘᴜʙɢ ᴄʜᴇᴀᴛs.
Documentation link : https://errorxcode.github.io/docs/utils/index.html
2) CloremDB
CloremDB is a simple, robust and easy to use embedded NO-SQL database for java applications. The data is directly saved as objects in the database. You can directly put POJO's in the database and can organize them is different volume. Each volume is like a SQL table which contains objects (as rows). You can have unlimited number of volumes and objects in it.
Documentation link : https://errorxcode.github.io/docs/clorem/index.html
3) EasyInsta
This is an android library through which you can use instagram programatically.You can say that this is a well optimize, will featured java wrapper of "Instagram graph API".You can direct messages, add stories, post photos, scrapping profiles and can do many more things with this library.
Documentation link : https://errorxcode.github.io/docs/easyinsta/index.html
4) Clorastore
This is a local implementation of cloud firestore for android. Clorastore stores data in form of documents as firestore and mongoDB does. The main aim of making this database is to make developer life easier. Programmer does not need to know that stupid SQL queries for just simple CRUD operations. This is the second easiest database ever made for android after CloremDB. Although, this is similar to those of Firestore and Mongo DB but also differ in some ways. In Clorastore, collections can a contain collection whereas document can't. Each document is limited to 10 MB.
Documentation link : https://errorxcode.github.io/docs/clorastore/index.html
5) Clorabase
Clorabase is a free and backend alternative for android apps. Clorabase is mostly made for apps which hardly requires online database and other android backend features. Although, this can also be used for the hybrid apps which often uses database and other features but considering firebase for that will be more beneficial. As the limits or quota are based on the assumption that the app will not fully depend on the server. The biggest advantage of using this instead of firebase for small apps is that you don't have to build an account in order to use clorabase. Yes, this service does not need account.
Documentation link : https://errorxcode.github.io/docs/clorabase/index.html
6) FloraDB
A modern No-Sql database written in java. World's 1st static database that can be used with just one utility class. Documentation link : https://errorxcode.github.io/docs/floradb/index.html