Under GPL-like licenses you are obligated to provide source code if you provide a binary. If you don’t distribute anything, e.g. you only use something privately, then there are effectively no obligations. Of course, if you don’t provide source code for your project (whether legitimately or not), then by definition your project is not open source in the first place.

Note that the GPL specifically does not require publishing the source code, or having to distribute it along with the binaries. It allows the alternative of only providing the source code upon request by any third party, to that same third party.

> Under GPL-like licenses you are obligated to provide source code if you provide a binary

No, this requirement applies only if you are using somebody's else GPL code, and it's meant to allow other developers and users to benefit from the work done.

It does not apply to the original author because the author owns the copyright of that code.

That seems to be disputed, see https://law.stackexchange.com/questions/27768/is-there-a-loo....

If you're redistributing someone else's GPL code in binary form, you also have to redistribute it in source form. A software license doesn't impose any restrictions on the person writing the code. It provides the conditions under which others can use it.

There are a few MUSTs if using GPL, yes (btw, GPL is considered a "free" license, not a "open source" one), but providing a repository is not one of them. Although you do need to provide the source (in any means you want, as long as it's accessible, making a repository is one of the ways, bundling a zip file would be another).

Short version of your obligations if using GPL as a license: https://tldrlegal.com/license/gnu-general-public-license-v3-...

Those are obligations if you're redistributing someone else's GPL code. You'd have to sue yourself to ensure compliance with your own license if it applied to you.

> btw, GPL is considered a "free" license

Yes.

> not a "open source" one

It is also an open source license.