In this short article I am going to highlight some of the programming languages and databases that top tech companies use as for 2022. Please feel free to contribute through comments.
Below is the list.

YouTube
Backend: Python, C++, C, Go, Java
Frontend: Javascript, Typescript
Database: Bigtable, MariaDB

Facebook
Backend: PHP, Erlang, Java, Python, C++
Frontend: Javascript
Database: MariaDB, MySQL

Yahoo
Backend: PHP
Frontend: Javascript
Database: MongoDB

Wikipedia
Backend: PHP
Frontend: Javascript
Database: MariaDB

Google
Backend: Python, Java, Go, C, C++
Frontend: Javascript, Typescript
Database: Bigtable and MariaDB

Pinterests
Backend: Python
Frontend: Javascript
Database: MySQL

Amazon
Backend: Java
Frontend: Javascript
Database: DynamoDB, RDS/Aurora, Redshift

LinkedIn
Backend: Java
Frontend: Javascript
Database: Venice

Instagram
Backend: Python (Django)
Frontend: React, Java, Object C
Database: Cassandra

Reddit
Backend: Python (Flask)
Frontend: Javascript
Database: Cassandra

TikTok
Backend: Java, Python, C, C++
Frontend: Swift, Kotlin
Database:

Twitter
Backend: Ruby, Java
Frontend: Javascript
Database: MySQL

Spotify
Backend: Python, Java
Frontend: Javascript (Boostrap)
Database: Cansadra