Personally, I think it should be closed, but not because it is easily Googled.
One of the almost stereotypical things about Stack Exchange is that we tend to be the first result in Google. Sometimes we can't and shouldn't compete with the first result, but when we can we should. It drives a lot of traffic here. (Note that over 80% of our traffic comes from search engines directly, and another big chunk indirectly!) Now that's not to say we should be copying and pasting popular pages into our answers. But just because something is easy to find somewhere else doesn't mean we can't accept it as a result here.
Some sites have a rule against that. For example, English has a rule against things you can look up in a dictionary (which is often the first result if you search for "thingiwantdefined definition") but plenty of others don't.
However, what OP did ask for is basically a list of apps they can use as a playground for API testing. I'm not entirely sure that's a great fit. What makes one app better than another? How would one go about picking a "correct" answer to such a question? As it stands, it isn't a good question for our format.
That's not to say his (his? her? sorry...) question doesn't add value. If it were answered, even non-objectively, it probably would add value. But adding value alone is not a good enough reason to keep a question open. We must continue to curate our questions so they fit the format, potentially guiding users with a quick comment where they can get their questions answered.
TL;DR - cool question, but bad for our format. Not because it's easy to Google, but because it's hard to answer objectively.