Code Browser by Woboq for C & C++
https://code.woboq.org/
Unity3D open source search engine
https://unitylist.com/
Source graphe
https://sourcegraph.com/search
Snipplr
https://snipplr.com/
Search 75 billion lines of code from 40 million projects
https://searchcode.com/
Programmcreek
https://www.programcreek.com/scala/
Source Code Search Engine
Find any alphanumeric snippet, signature or keyword in the web pages HTML, JS and CSS code.
https://publicwww.com/
Piwik code search
https://piwikcodesearch.herokuapp.com/
Openhub
https://www.openhub.net/
Libraries.io monitors 4,282,138 open source packages across 38 different package managers, so you don’t have to.
https://libraries.io/
Google open source code
https://code.google.com/
Saerch for java and javascript
https://www.codota.com/code
CSS HTML JAVSCRIPT
https://www.codeseek.co/
https://codefinder.org/
Source Code Search Engine
http://www.codase.com/
Open source software nasa
https://code.nasa.gov/
Oracle code source java
https://community.oracle.com/tech/developers/categories/13287-java
Software heritage