There are a lot of uncertainties in this area. For example, if you provide journalistic content on your website (e.g. regular blog postings, even for free),then this could be interpreted as an opinion-forming activity, which in turn requires an imprint.

(Source [German]: https://www.e-recht24.de/artikel/datenschutz/209.html )

The Bundesministerium der Justiz und für Verbraucherschutz seems to give a similar opinion:

http://www.bmjv.de/DE/Verbraucherportal/DigitalesTelekommuni...

I'm reading from the English translation here, but it suggests that "businesslike" also includes something that is ongoing / sustained. So if your personal blog is posted every Tuesday, it could be said that is "businesslike" (geschäftsmäßig). They also specify that profit is not a requirement.

The "I have a blog and now I need an imprint" faction is essentially FUD.

Geschäftsmäßig doesn't require Gewinnerzielungsabsicht (intent to make a profit), but does actually require an intent to make business, in whatever form, but not necessarily on the site itself. For example, a business owner having a very simple website just stating what his business does will require an imprint on that site, because obviously the intent of the website is to inform about his business. If, on the other hand, you have a blog with no ads about your kittens then you don't need an imprint.

Just because something is an unbestimmter Rechtsbegriff (non-exhaustively defined law term) doesn't mean you can just go ahead and act as if it means anything you like.

I've given you an upvote, as that does seem to make sense.

But to confirm, the particular quote from the BMJV that I was going by on that page is this one, does it match with your understanding? (My German comprehension isn't great.)

"Die Anbieterkennzeichnungspflicht muss praktisch von jedem, der ein Online-Angebot bereithält, erfüllt werden. Etwas anderes gilt nur bei Angeboten, die ausschließlich privaten oder familiären Zwecken dienen und die keine Auswirkung auf den Markt haben. Im Zweifel sollten Sie davon ausgehen, dass die Anbieterkennzeichnungspflicht besteht."

The first sentence seemed to say that "in practice everyone offering something online must comply", and I took "privaten" in the second sentence to imply private as in "password protected / not publicly accessible". But as someone learning German I've probably interpreted those too narrowly, and I'd love to be corrected on the nuance!

> die ausschließlich privaten oder familiären Zwecken dienen und die keine Auswirkung auf den Markt haben

which exclusively cater to private/family needs/affairs and [thus] have no impact on the markets.

> I took "privaten" in the second sentence to imply private as in "password protected / not publicly accessible".

No, privaten Zwecken here refers to personal affairs.

Holy wow, that seems draconian! Is it solely so they can find you and prosecute you for your opinions? (serious question)

That has nothing to do with opinions but being able to contact someone if laws are broken etc.

Playing devil's advocate, it can be argued in some cases that even if your private homepage met that criteria, its purposes could be to advertise/establish/further your personal "brand" thus is for business purposes. For example, if you blogged about technical topics that could benefit your employment opportunities in the technical fields and get you speaking engagements. There's examples of people who have built careers solely from personal blogs/homepages.