There’s no playbook for stepping into a cofounder role at a startup you didn’t build.
Becoming a cofounder wasn’t part of the plan when I joined Klaro — a company helping low-income employees increase their purchasing power through unclaimed social benefits — as a freelance CPO. Solo founder Cyprien Boutard Geze had spent four years building a company known for a value proposition clients loved which had great traction, but like many startups at this stage it was starting to hit a ceiling. Processes that worked in the scrappy early days weren’t holding up under the demands of growth. The team wasn’t focused enough on execution. Targets were slipping, and the cracks were showing.
My focus was first on putting in place a product-centric culture — but that evolved into wider conversations with Cyprien about Klaro's long-term vision. Before I knew it, stepping into the role of cofounder felt like the next logical step.
Around this time, I met Augustin Celier, partner at Hexa Scale, who has seen this happen a lot. Hexa Scale works with startups to break through growth challenges, and helped e-signature company Yousign do this by bringing on Alban Sayag as a late cofounder. The company tripled its customer base and raised a Series A.
Talking with Augustin made me realise that late cofounders like me are becoming more common as startups face pivotal moments, but the role remains misunderstood. It’s a very tough, very rewarding role — you need to drive change and make tough calls while earning trust and respecting what’s already been built. A balance that's not easy to strike.
So, with Augustin, I wanted to explore what it takes to make this dynamic work. It all starts with empathy, humility and a solid strategy.
1. Negotiating equity in a company that’s already built
Joining as a late cofounder means balancing two things: asserting your value while respecting the work that’s already been done. Few moments test this balance more than negotiating your equity in the company.
At Klaro, this wasn’t a quick or easy process. Cyprien and I took an informal offsite to hash things out, stepping back from the day-to-day to focus on what mattered most to each of us. As a late cofounder, I knew I wouldn’t have the same equity stake as someone who’d been there since day one, that’s just the reality. The equity pie had already been sliced, and my stake had to reflect the impact I could bring without undermining the foundation Cyprien had built.
What made the negotiation work was keeping it practical. We focused on how my role would evolve and what results would define success. Rather than fighting over every percentage point upfront, we made sure to keep it flexible, knowing that as I grew at Klaro, we could always revisit the equity conversation later.
Augustin’s take:
Milestone-based vesting is a smart way to align founder and late cofounder interests. Equity can be structured using a mix of:
- Time-based vesting: A portion of equity vests gradually over time, rewarding long-term commitment.
- Milestone-based vesting: Equity vests as the company progresses from one revenue tier to the next. ARR is a big one in SaaS — for example, moving from €2m to €5m, then €7.5m and finally €12m.
- Exit valuation-based vesting: Some equity vests only at exit, depending on how much the company’s value grows. For example, equity might vest proportionally as the price per share increases between 3x and 5x the initial value when the cofounder joined.
This flexible approach ensures accountability while giving late cofounders a clear path to earning their stake through measurable results. Plus, if expectations are exceeded, renegotiation is often possible as trust builds.
2. Finding your place in the founding team
Joining an established founding team comes with its own dynamics. For me, stepping into Klaro was about redefining what leadership meant alongside Cyprien.
One of the hardest parts of finding my place was balancing respect for what Cyprien had built with the need to assert my leadership. I was stepping in as the 'new partner', but I had ideas that challenged the way things were done. Figuring out when to speak up, when to hold back and how to build trust without overstepping was a constant balancing act. Meanwhile, Cyprien had his own adjustments to make — shifting from a hands-on leadership style to one that focused more on strategy and growth.
One moment that stands out was when we discussed how to handle team communication. Cyprien had always prioritised staying close to the team, personally addressing concerns as they arose. It was one of the things that made Klaro’s culture so strong early on. But as the company grew, that approach started to stretch him too thin. I raised the idea of leaning more on managers to handle day-to-day issues and only using structured rituals — like ad hoc Q&A sessions led by Cyprien when there was particularly ‘big’ news — to communicate directly with the wider team.
This meant encouraging managers to develop the habit of checking in during 1:1s to address any concerns employees might have, rather than relying on Cyprien to handle it. For example, when someone was leaving the company, the manager became the primary point of contact for employees to raise concerns, whereas previously, they would have turned to Cyprien.
It was an adjustment for both of us. Cyprien was stepping back from something he genuinely valued, and I was navigating how to challenge his approach without overstepping.
In the end, the conversation helped define how we worked together. Cyprien’s openness to adapting his role built my confidence in speaking up, and my respect for his care and vision strengthened our partnership.
Augustin’s take:
Building trust as a late cofounder requires humility on both sides. Founders and late cofounders need to approach the relationship with the mindset that they each have something to learn from the other. For founders, this might mean being open to fresh perspectives on scaling or operations; for late cofounders, it’s about respecting the founder’s vision and acknowledging the groundwork they’ve already laid.
Equally important is maintaining open communication and constant feedback. Regularly checking in — whether it’s to clarify priorities, address concerns or adjust approaches — keeps alignment strong and prevents misunderstandings.
3. Reshaping the culture without losing its heart
Klaro had a strong sense of care within the team — people genuinely looked out for each other — and everyone was deeply motivated by the company’s mission and impact. That collective spirit fostered creativity and built bonds that were vital in the early days.
But as the company grew, it became clear we needed to tighten things up. When I joined, the culture had a laid-back vibe — long lunches and the occasional Mario Kart sessions were part of the day. While this helped build camaraderie, it also masked how the business was really doing. Many team members didn’t fully grasp the company’s challenges.
The biggest shift came with restructuring and bringing in senior leaders — hiring a CTO, head of sales, CMO and head of ops. This allowed Cyprien and me to focus on Klaro’s future rather than day-to-day operations.
We introduced company-wide and team-level OKRs, with quarterly planning and reviews. Management training sessions were held to share best practices, and we implemented competency grids to clarify role expectations, paired with biannual performance reviews.
It allowed the team stayed motivated and united, but now with a sharper focus on results, alongside the existing focus on impact and well-being.
While some found the changes difficult, and a few chose to leave, they ultimately helped us retain the people most aligned with Klaro’s mission and set the foundation for sustainable growth.
Augustin’s take:
As a late cofounder, your job is to elevate the company’s execution culture. This means professionalising processes, driving accountability and ensuring the team is aligned on delivering results. This means making tough decisions — deciding what needs to change to help the company grow and what should remain untouched because it’s part of the company’s core DNA.
The challenge is that these decisions often aren’t popular. You’ll need to hold firm during tough discussions and follow through on hard calls, even when the pushback is strong. But when you commit fully — when the team sees you leading by example and following through — the rewards are huge: a more focused, resilient culture that’s ready to scale. Half-measures, on the other hand, only prolong the problems you’re trying to fix.
The outcomes
Stepping into a late cofounder role isn’t for everyone. It’s messy, uncomfortable and full of grey areas. You’re tasked with balancing respect for what’s been built while leading necessary change, often in the face of resistance.
But when it works, it really works. At Klaro, we doubled sales and increased ROI on product improvements by 200% in just 12 months. Beyond the numbers, it’s been rewarding to help channel the team’s energy into something scalable without losing what made the company special in the first place.
As Augustin has seen time and again, late cofounders can play a crucial role in helping navigate growth inflection points. It’s not about replacing the original founder’s vision, but about complementing it with new skills, structure and a shared commitment to the future. That’s what made it work for us, and it’s why more startups might benefit from embracing late cofounders when they need to level up.
