compete.comは安全ですか？

Advertising/tracking, but relatively innocuous as such. It doesn't seem to be strictly necessary to have it allowed in order to get websites to work, so there's no real need to allow it. Unless you want to vote with your pocketbook and feed a fraction of a penny in advertiser revenue to the owners of the site that you encountered it on...and everyone else who uses the service...and contribute to your online data profile...but that's your call.

The quality of their web analytics is not consistent. I have seen their statistics questioned often, and they sometimes agree, but often vary a lot from other sources. The site itself offers little unless one is a paying subscriber, most services are now blocked otherwise. Note that the developer page with API is an HTTPS SSL secured site, unlike the main site.