Uber

I am not an Uber user,, so please excuse my ignorance, but does not the uber site advise where they have service?

I found this map showing where you can use Uber in the Netherland.
https://www.uber.com/en-NL/blog/uber-netherlands-what-is-uber-and-where-can-i-ride/

Europe has a wonderful public transportation system that is reliable and economical.
spent two weeks last year in the Netherlands and Belgium.
Relied solely on public transportation
did not have any problems.

Very easy to travel between Amsterdam-Haarlem-Delft via train. Within Amsterdam, Ubers are quite available but shouldn't be a primary option for traveling within the city. Ubers can be scarce on weeknights (esp. later in the evening) and if using on weekends, be mindful that streets in the center (esp. near Red Light district) are closed at night and it can be quite the challenge to get around via Uber b/c of that. Learned that the hard way during my recent visit to Amsterdam where on a Friday night, requested an Uber after dinner from a restaurant on the perimeter of the Red Light district, only to have 7 Ubers cancel on me and then waited 10+ minutes for the 8th Uber to pick us up, with the driver calling me and telling us to meet him blocks away from our requested pick up location b/c of street closures and usual late-night traffic on nearby streets b/c of it.

Yes, one can use the same Uber app as you use anywhere.

As mentioned in the comments above, public transport is excellent and save in all three cities!

Haarlem & Delft attractions/hotels are all in walking distance

After Late night dinner you might consider taking Uber

We were a party of four, so Uber made a lot of sense in Amsterdam. It was not as difficult or expensive to get around as I expected (most trips were less than $10, so less than four tram tickets). However, our hotel wasn't very convenient to the tram, so we didn't invest in a pass--that may make more sense depending on your location and party-size.

We used the same Uber app that we use here. If Uber doesn't serve the other towns, then MyTaxi might (which I've used elsewhere in Europe).

I agree with Jake. Last September was my 4th trip to Amsterdam in 4 years. Very familiar with their awesome public transportation, and getting around Amsterdam and the Netherlands using it. On my last trip in September - I was traveling with a group of 6. Many times it was much cheaper and/or quicker to take an Uber in Amsterdam and some surrounding areas. For instance our day trip to Haarlem, Uber was much cheaper than public transportation and literally door to door service, which was nice because we were on a time crunch. I'm learning it really depends on where you are traveling to and from and how many there are of you. I also don't want to take away from the Uber drivers in the Netherlands, after speaking to several of them, it's definitely not like the States. They pay a lot of money to drive for Uber and have lots of regulations, requirements, and need a special piece of equipment to do so. I believe one driver mentioned he paid 4K Euros to drive (not sure if he was pulling my leg). I don't know about Delft. In Bruges, we just took Uber from the train station to the hotel. Again, it's about your preference, what's cost and time effective for you.