One evening last summer, Jule Müller and Anni Kralisch-Pehlke were about to call it a night at their local bar in Berlin's Neukölln neighbourhood, when the conversation turned to dating. "We asked ourselves why so many of our friends are still single," Kralisch-Pehlke said. "And then we came up with a business idea: to mix a lifestyle blog with a dating blog."

The two spent the next week browsing websites in the UK and the US for similar concepts that help singles in big cities find love. When they couldn't find one, they decided to start their own. With that, imgegenteil.de was born.

Since the site's debut in December last year, it has grown into a symbol of what Kralisch-Pehlke, 30, and Müller, 31, have dubbed the slow-dating movement. Indeed, im gegenteil, which means "on the contrary" in German, is the polar opposite of smartphone dating apps that tell you who in your immediate vicinity is looking to meet up for a drink… or more. A common complaint from users of conventional dating sites or apps is that the user selects old and unrepresentative photographs and, intentionally or not, writes a totally inaccurate description of themselves. To avoid these problems, im gegenteil takes a refreshingly different approach: each profile features a portfolio of pictures shot by Müller that have been taken in and around the hopeful's home – the style could be described as studied yet casual – of the dater relaxing on their sofa or brewing a coffee. In addition to the photos, each page features a 300-word profile, written by Kralisch-Pehlke, that summarises what the two learned about the interviewee. The end result wouldn't look out of place on the pages of a glossy lifestyle magazine. A contact form at the bottom of the profile allows anyone on the internet to write a message to the profiled person's inbox on the site.

"It's online dating, of course, but our approach is totally different," Kralisch-Pehlke said. "It takes us a day to make one profile. We spend three, maybe four hours doing the interview. We put the profile together and then send it back to the person for approval. It takes a lot of time and I think people can tell."

The profiles leave out what they call "superficial facts," such as how long singles have been on the dating market, how tall they are or what they are looking for in a mate. "It's not this fast hook-up site," Müller said. "On our site, you actually have to take time to scroll through the pictures and read the texts."

So far, there are 75 profiles on the site, mostly of people living in Berlin or Hamburg. But that low number disguises im gegenteil's popularity: tens of thousands of people are reading the site's profiles and dating blog every month, the founders say. And hundreds of people from around Germany have applied to be profiled. "We wish we could take all of them," Müller said. "We try to do three portraits a week. Then comes the other work associated with our business – press, writing the blog, and partnerships."

Karl Nowak was one of im gegenteil's first users. The 28-year-old, who is working at a music industry startup, hasn't found love yet, but he likes the attention he has received. "The first couple of weeks were overwhelming," he said. "Something like 50 or 60 women wrote to me."

Wyndham Mead, an American who has lived in Berlin for the past three years, joined because he was looking for an alternative to "impersonal gay dating sites". "The nice thing about this site is you're getting someone else's voice and perspective on your life," he said. "And that automatically produces a more authentic picture for the rest of the world to see."

Mead said he liked the way in which he and others profiled on the site could swap stories in a closed Facebook group moderated by Müller and Kralisch-Pehlke. One of the most discussed stories in that Facebook group was Janina Fischer's. The 29-year-old project manager and mother of a young daughter had tried various dating sites, but was turned off by the way they would always recommend that she contact "45-year-old middle managers in the Saarland or much older guys". "I felt like I wanted a different match than what most dating sites were giving me," she said.

Within a few weeks she met a man through im gegenteil, after a mutual friend had liked photos from her profile that she had posted on Instagram. The date went so well, she said, that she almost immediately changed her status on the site to "no longer searching". Fischer said the holistic picture painted of her life – she wasn't just a single mother– was key to attracting the man she is now dating.

"The thing about this site is that it is super-public – you're going public with your desire to find someone," Fischer said. "It's not anonymous like other dating sites. But maybe that's why it works."

Müller and Kralisch-Pehlke say 25% of im gegenteil's users have found a relationship through the site since its inception. Encouraged by this success, the duo quit their day jobs last winter to work full time on the business.

Im gegenteil generates income through product giveaways and endorsements. The founders plan to add advertising and marketing tie-ins so that they can continue to offer free profiles. In order to reach their goal of about 1,000 profiles, they are contracting writers and photographers from around Europe – and hope to launch English-language versions for London and New York in the coming months.

But will the site lose its personal touch if it grows? The founders say no. "Even if we have a thousand people, we can keep in touch with everyone on the site," Kralisch-Pehlke said. "Just like you do with your own friends on Facebook."