“I would be lying if I didn’t admit that I have been in a real funk these last few days over this news,” writes Foursquare founder Dennis Crowley, speaking about the company’s plan to sunset the Foursquare City Guide app later this year in favor of focusing on its check-in app Swarm. The move reverses Foursquare’s ambitious 2014 decision to split up its app into two different properties: one for exploration and discovery and the other, Swarm, for sharing your location to find nearby friends.

The Foursquare app’s closure, scheduled for December 15 of this year, isn’t surprising. It’s been a long time since Foursquare was talked about in the same breath as other social networks. When Foursquare launched, people were competing to become the “mayor” of their favorite venue and were less concerned about the safety issues of sharing their real-time location online.

Still, Foursquare’s original app had been a clever way to explore cities and their offerings, as an early example of how social networks could leverage smartphones’ location capabilities to build an entirely new type of experience.

Now that mass of collected data that fueled the company’s City Guide will disappear for its end users.

In an email sent to users, Foursquare writes, “After many wonderful years of leaving tips and reviews around the world together, we’ve made the tough decision to say goodbye to the City Guide app …” The app itself will shutter on December 15, with the web version to soon follow, the email noted.

The move prompted Crowley to become a bit nostalgic about what it’s like to say goodbye to a product he had worked on for so long.

In a post on Threads, the founder wrote, “I have a really good blog post somewhere in me about ‘the danger of falling in love with the companies you build & products you create,’ but it’s not the right time to write it. The ‘neglect of FSQ’s apps’ story [has] been a drumbeat in my personal online experience for like 5 years now and I let it affect [me] more than I should (aka: ‘dude, just get over it’ is easier said than done).”

While Foursquare the company continues to survive — Crowley notes it has over $100 million in revenue in his subsequent post — the focus of its efforts will now be on the check-in portion of the experience, not the City Guide.

He also takes the time to shout out the “old-school” Foursquare consumer product, engineering, and infrastructure teams for all their work over the years, as well as to the “super-user” community that kept the app going this long.

“I’m genuinely curious what FSQ (the company) is going to do [with] Swarm, and will always be rooting for the team and products,” Crowley added.

The founder is not the only one lamenting the shutdown. Other users and fans of Foursquare, both past and present, have posted how they feel about the app’s closure, describing it as a “gut punch,” “sad,” or simply offering their “RIP”-style condolences.

Josh Williams, who previously co-founded Foursquare’s main competitor, Gowalla, gave the app a nice send-off as well, remarking on how different the web used to be at the time these apps were mainstream.

“I know we can moan a lot about how the internet used to be fun and this and that, but there’s certainly a truth to it. Our quest for efficiency has robbed us of some joy,” Williams wrote on Threads. “I’m still convinced there are successful products to be made that connect people IRL, but it is a tough road to walk. Foursquare made the web and our digital lives a much better place,” he added.

Crowley is no longer involved with Foursquare in a full-time capacity but still remains co-chair of the company’s board. Instead, he has been working on “something new” since August, per LinkedIn.