I am argentinean, male, born in 1977.
I am a mathematician.

LaTeX

Fluent.

freeCodeCamp certifications

Responsive Web Design certification

W3Schools

Some people says that w3schools.com is a low quality resource,
full of mistakes, or that it is useful only for newbies, at most.
Anyway, I am having fun there.
I have completed the following tutorials in w3schools:

HTML, CSS, JavaScript,   
SQL, MySQL, PHP,  
Python, Pandas, NumPy, SciPy,    
C++, C#,  
Java, Kotlin, Go, R,  
Git, GitHub,  
XML (AJAX, DOM, XPath, XSLT, XQuery, DTD, XSD,  
Web Services (WSDL, SOAP, RDF, RSS)),  
Node.js, React.  

In all cases I read the material, completed the exercises and solved the queeze, achieving 100% in all cases.
Thus, I now have, at least, a basic knowledge of all those topics.

C

My preferred language is C.
Interested in standards C11 and C99.
Visit Sempha, my Youtube channel!!
There you can find my C programming language tutorial (in Spanish).

C++

C++11, C++14, C++17, C++20.  

I have a good level of C++.

Python

Python3, Pandas, NumPy, SciPy.