Is it "crowd" or "croud?"

Solution 1:

The correct spelling is "crowd" for both the noun and the verb. Or at least that's how it is now.

Wiktionary is correct that at one point in time it was spelled "croud". Because this spelling is no longer used, it will not be listed in regular dictionaries. According to the Oxford English Dictionary, this spelling was used 1500-1800 (the exact range depends on which noun or verb sense we're talking about). Here is an example of this old spelling from 1709:

There croud into his Mind, the Ideas which compose the Visible Man, in company with all the other Ideas of Sight perceiv'd at the same time.
_{An essay towards a new theory of vision.}

It's important to note that using this spelling nowadays is always an error. It's not used even when trying to imitate older English spellings.

Solution 2:

Crowd is the correct spelling regardless of historical spellings, to which there are many words in the vernacular that have transitioned through syntactical updates.

In the here-and-now, it is crowd: See Interest over time on Google Trends for crowd, croud - Worldwide, Past 12 months - https://g.co/trends/SqAhk