What was your first major Open Source Contribution?

not a major one but the first : this is funny because the first open source contribution was just adding the dev.to logo icon to the simple-icons project

"Major"? Pending...

As mentioned in an earlier comment: dev.to/phlashgbg/comment/2okc

..I wrote a device driver and tar implementation for backing up MS-DOS machines to 0.25" cartridge tapes. Getting it accepted to the Simtel archive was a learning experience, I had to have everything documented, buildable with the listed tools and supply tests - it's almost like they wanted people to use it :) Good lessons to take to the next project!

Mine was this pull request github.com/ipython-contrib/jupyter... which I did instead of my Machine Learning homework because I kept failing matrix multiplications. Overall I got great feedback and really enjoyed it.

In terms of lines of code, an example for Cycle.js

Otherwise, I fixed some bugs I found or added something to the docs after I searched it for hours in the code, hehe. They all could have small or big impacts, depending on how people used it.

Not sure about major, but first one was open source library for work with an API of one affiliate program: travelpayouts-js (it doesn't have english readme at this moment, sorry :))

My first OSS contribution was in github.com/a8m/documentdb-go

What I liked the most was that feeling of satisfaction after seeing my first PR had been merged :)

My first was also my biggest, open-sourcing a library I wrote for work: github.com/ioof-holdings/redux-sub...

Typographical errors, improvements/suggestions. in the README.md :)