Cezar Grigore is a London founder who has spent the better part of a decade building companies on top of a single, shape-shifting thing: Instagram and the creator economy that grew up around it. A mathematics and computer science graduate who went through Y Combinator in 2016, he did something less expected afterwards — came home to London and built a pair of focused marketplaces, Social Cat and Clip, for the small brands most marketing software ignores. What drew us in was the pattern underneath the companies: Cezar keeps building the tool he needs, and then noticing that everyone else needed it too.
One platform, read for eight years
Most founders who build on a social platform catch one wave and ride it until it breaks. Cezar has done something rarer. In 2018 his company Tremo Books turned an Instagram feed into a hardcover photo book, back when Instagram was still, for most people, a photo album. A year later he was shipping a small tool for finding which Instagram accounts actually move product, as the platform tipped into commerce. In 2022 Social Cat arrived as a marketplace pairing small brands with micro-influencers — people with a few thousand engaged followers rather than a few million passive ones. And in 2023 Clip went a step further: short videos made by vetted creators for a brand's own adverts, never posted to the creator's feed at all. By then the platform had become a production studio, and Cezar had a product for that too.
Seen in sequence, these aren't four bets. They are one long reading of the same room. Each product fits the platform as it was at that moment, which suggests someone paying close attention to how ordinary people actually use their phones rather than how the industry says they do. There is a lesson in it for anyone building anything: staying in one domain long enough to see its next turn beats chasing a new domain every eighteen months.
Build it for yourself first
Build it for yourself first
Four companies in a row, and each one started as something the last one needed. How a photo-book startup turned into two creator marketplaces.
2018: a book made from a feed
Tremo Books printed hardcover photo books from people's Instagram accounts. To sell them, the small team leaned on Instagram influencers. That worked well enough to raise a question: how do you find the ones whose followers actually buy?
2019: the answer became a tool
Influencer Wizard analysed which accounts a brand's customers were really listening to. It was a side project with a modest launch, but it was the first time Cezar had packaged his own marketing problem as software.
2022 and 2023: the tool became two companies
Social Cat turned that idea into a subscription marketplace for small brands and micro-influencers. Clip followed a year later for made-to-order video. Same office, same co-founder, same instinct: solve your own problem well enough and other people will pay for the solution.
Who knows whom
The thread that runs furthest back is older than any of the Instagram work. The company Cezar took through Y Combinator, Index, tried to map professional relationships — to tell you who in your network knew the person you wanted to reach, and how well. It didn't last, which is true of most accelerator companies and no shame at all. But the idea at its centre never left him: an introduction, done right, is itself a product.
Everything he has built since is a matching system. Social Cat pairs brands with creators. Clip pairs brands with video makers. Even his years between companies, running engineering for other London startups, included a stint at a two-sided marketplace. And the detail that tells you most about how he thinks is the gate on the supply side. Clip accepts a small fraction of the creators who apply, and does it with human eyes rather than an algorithm. For a technologist, that is a deliberate choice: he has decided that in a marketplace the real craft isn't the matching engine, it's deciding who gets to be matched at all. A brand paying a hundred dollars for a video doesn't want ten thousand options. It wants the right fifty.
Both halves of the company
Technical founders tend to fall into a type: they build, and someone else sells. Cezar is the exception, and the evidence is scattered across his career in ways that are easy to miss.
Fresh out of Imperial, he went not to a tech accelerator but to the Royal College of Art's business incubator — an art and design school, where a maths graduate would have been surrounded by people who think about objects and users before they think about systems. At a London fintech in 2021 he held two titles at once, Chief Technology Officer and Chief Growth Officer, which is a strange thing to be given and a stranger thing to accept unless you can actually do both. And today, at Social Cat, the person writing the long how-to guides on influencer pricing and outreach is not a content marketer. It's him.
That combination explains a great deal about why his companies feel the way they do. His co-founder, Stefan Afrăsinei, is a growth marketer by background; Cezar can meet him in the middle of every conversation. Products built by people who understand distribution tend to be priced for the customer rather than the investor, and both Social Cat and Clip are priced for a small brand's monthly budget. Someone who can write the pitch and the code doesn't need permission from either side of the company to make a decision.
- A maths graduate at an art schoolRoyal College of Art business incubator, LondonStraight out of Imperial's maths and computer science degree, Cezar chose a design school's incubator over a tech one — an early sign that products and users interested him as much as systems.
- Two titles on one doorSecured, LondonHe served as Chief Technology Officer and Chief Growth Officer at the same time. Most companies split those jobs between two people who argue; he held both sides of the argument himself.
- Writing the playbook himselfSocial Cat blogThe founder who built the platform is also the one writing its long guides on influencer pricing, vetting and outreach. Few technical founders bother to learn the customer's language this fluently.
Back from the Valley, down to Camden
Here's a path that happens less often than it should. Young engineer from Romania studies at Imperial, gets into Y Combinator, moves to San Francisco. The script says: raise a large round, grow headcount, chase a billion-dollar outcome or go down trying. Cezar kept the credential — his profile still says YC alumnus — but changed the script. He came back to London, teamed up with a fellow Romanian, and built two companies out of one small address in Camden.
Romania sends an unusual number of strong engineers into London's startup scene, and there is a recognisable flavour to how the best of them operate: technically fluent, unsentimental about hype, comfortable building something that simply works and sells. Cezar's choice of customer fits that temperament. Two thousand small brands paying a modest subscription is not a story that gets a magazine cover. It is a business that survives a bad year, and that gives its founder the freedom to keep building.
The next tool he needs
Which brings us to what he's doing now. In 2025 Cezar launched Tailored, a platform for creating AI employees — agents you onboard like staff, give responsibilities, and correct until they get the job right. He has also been tinkering with AI agents and iPhone apps on the side, which for someone with his history is less a hobby than a scouting trip.
It's hard not to read Tailored as the ladder continuing. Anyone running two lean marketplaces spends their days on outreach, support, vetting and follow-up — exactly the repetitive, judgment-adjacent work that agents are now good enough to attempt. It would be entirely in character for Tailored to have started as the tool Social Cat and Clip needed. And it resolves the tension in his earlier work rather neatly: keep humans on the decisions that matter, like who gets through the gate, and let the machines carry everything around it.
Whatever comes of it, the method is the thing worth copying. Build what you need. Watch who else reaches for it. Stay in the room long enough to see what it turns into.