Is it legal to put someone else's project on github?

Question

Law in IT

The customer threw money.
His project is in YIi2, without any licenses at the root of the project.
The sediment remained unpleasant, I want retribution.
I will post the project on github for free access, will I get something for it?
Does that mean they can sue me or something?
The project is commercial, selling keys to games in steam.

Answer 1

You can post your written code, for which you were not paid, with peace of mind.
If you signed any non-disclosure papers there, then even in the case of a scam, laying out will be considered arbitrariness or something like that. And if they didn’t sign, then knowing the current uncertainty of the scales of justice, there may not be anything, but they may also be accused of illegal access.

Answer 2

Record a video of your working code with a voice (in the form of an overview presentation of the software product) and an explanation of everything that happens on the video, and put it on YouTube.
In the portfolio - place a description, price tag and a link to the video.
Who will be interested - will buy!

Answer 3

Post the code that you personally wrote if you were not paid for it - yes. But to spread the code that you were given to work, written not by you, but by other developers for your customer - from a legal point of view, you will violate copyright. However, it will not be so easy to prove something against you, especially if the github account is not associated with you and you did not sign a work contract.