I did not realize we needed to buy tickets early for Anne Frank House and they are now sold out. However, the website mentioned that 20% of tickets would be sold on the day - what time, online, in person? Please LMK if you have experience with this.
The website is pretty clear that all ticket sales are online. I would suggest that you log in early in the day your time and see if the tickets have been released yet for that particular day. That will start to give you an idea of when they become available each day.
Also, here is a link to the contact form where you can contact the Anne Frank House directly with your question.
Also look at the availability of admission tickets with the inclusion of the introductory program. These tickets tend to go on sale about only two weeks prior to admission date. These tickets are just a few euros more than the standard ticket, but include a 30 minute program before the start of the visit that puts the history in context. When those standard tickets are released two months out and are sold out quickly this is most certainly an option.
When u go online for ticks , remember there's a time difference . It's 7 hours later in NL if you live in Central time . You can do the math for the other time zones . So if they go on sale at 9 am in the Netherlands ( museum opening x ) it's 2 am , middle of the night in central . You will have to stay up a bit but may have a better chance . Unless of course the website sells ticks 24/7 .
I was just there a few weeks ago and anyone who did not have an online reserved ticket was turned away completely. The website clearly states that due to construction, ALL entrants must have a reserved time slot. Having said that, I would keep checking because the construction was supposed to be over by the end of June (and it wasn't when I was there in July). Once it's over, they may open entries to walk-ups as well.