Widget.datablocks.se is currently showing a 'Bad Gateway' error, which means the site is not working. But even beyond that, there are serious trust issues. The domain's WHOIS record is hidden, so you can't find out who owns it. There's no about page, no contact information, and no social media presence. For a site that's been around for 6 years, that's a glaring lack of transparency.
While the site hasn't been flagged by Google or blacklisted, the complete absence of identity and transparency makes it impossible to assess its legitimacy. If this were a personal project, some of these gaps would be acceptable, but a hidden WHOIS is unusual for any site that resolves to a live server.
Before you interact with widget.datablocks.se in any way, wait for it to come back online with clear ownership and contact details. Until then, treat it as a suspicious placeholder.