Scaling an engineering team is one of the most critical — and risky — phases in a startup’s journey. Done right, it creates a strong foundation for innovation and growth. Done wrong, it leads to silos, slowdowns, and cultural fragmentation.
In 2025, I believe scaling successfully isn’t about hiring at top speed — it’s about scaling intentionally, with structure, flexibility, and purpose. At Moss, where I serve as co-founder and director of engineering, we took this principle seriously. Moss is a European fintech platform offering smart expense management and corporate credit cards. Over the past few years, I helped grow our engineering team from 5 to over 50 people across several locations. We also built a 20-person R&D center in Tallinn, Estonia — one of the best decisions we made for long-term product delivery and culture.
Here are some core lessons we learned — ones I think will resonate with founders, CTOs, and engineering leaders navigating similar growth in 2025.
Avoid the Hypergrowth Trap: Scale with Intention
One of the earliest decisions we made was to avoid hiring reactively. Instead of rushing to add headcount after raising our Series A, we planned growth in stages. We made sure the team was ready, onboarding was solid, and infrastructure could support it.
That meant maturing documentation, defining ownership, and aligning hiring with product milestones. It helped us avoid the trap of hiring faster than we could absorb people, which often leads to confusion and low morale.
Build Flexible Structures: The Mission and Core Model
To scale effectively, we introduced a structure that let us balance innovation with stability. We split our engineering org into two team types:
Core Teams (around five engineers) are responsible for platform health, reliability, and maintaining existing features.
Mission Teams (two to three engineers) focus on building new features or running experiments. These teams are time-boxed to three months and aligned to specific outcomes.
This gave us a fast lane for innovation without compromising platform stability. For instance, one mission team built and validated a localized invoicing feature for the DACH region in under eight weeks. Afterward, we handed it off to a core team for long-term maintenance.
We were inspired by Spotify’s Squad Model but made it our own by rotating engineers between mission and core work. This kept engagement high and helped avoid silos.
Organize Around Tribes for Cross-Functional Focus
As we grew, we grouped teams into tribes — cross-functional units of 15–16 people, including engineers, product managers, and designers. Each tribe focuses on a product domain or technical area and owns its roadmap and delivery.
Each tribe has leadership, including an engineering manager and a group product manager. This model gave our teams autonomy while maintaining alignment. It also allowed engineers to move between teams within a tribe more easily, maintaining context and momentum.
Tribes became the backbone of our scaling journey. They created a sense of identity and purpose while giving teams room to operate independently.
Hire for Adaptability, Not Just Experience
Rather than hiring specialists in a specific stack, we prioritized engineers who were curious, flexible, and eager to learn. We encouraged everyone to work across the product — from backend services to frontend UI, and sometimes into DevOps.
That adaptability became one of our superpowers, especially when we expanded into new products. Engineers were used to jumping into new domains, which made scaling smoother and faster.
Plan Your Roadmap Before You Scale
We don’t do ad-hoc planning. Every quarter, our engineering managers and product leads create a roadmap, align on outcomes, and define staffing for each mission.
When we decided to enter the French market, we didn’t wait until the last minute. Three months before launch, we had a mission team working on localization, compliance, and integrations. By launch time, the groundwork was in place.
That kind of planning made it easier to onboard new engineers and gave our teams clear visibility into priorities.
Balance Speed with Sustainability
We scaled fast — but never recklessly. Every decision was balanced between delivery goals and long-term technical health.
We built rituals to stay aligned: tech huddles, architecture discussions, quarterly tech reviews, and retrospectives. These helped us identify debt early, review pipelines, and keep best practices consistent.
One moment stands out: After a rapid series of launches, we paused to refactor legacy components that were slowing us down. That investment paid off — helping us avoid critical downtime and reducing incidents.
Final Thoughts: Scale Smart, Not Just Fast
Startups in 2025 are under pressure to grow. But real growth comes from thoughtful systems, intentional hiring, and strong feedback loops — not headcount alone.
Our team didn’t grow from five to 50+ engineers by accident. It happened because we did the following:
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Hired adaptable, collaborative engineers
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Structured around missions, core responsibilities, and tribes
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Planned roadmaps carefully
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Invested continuously in feedback and tech health
If you’re scaling this year, I encourage you to go beyond headcount. Start slowly. Build with purpose. Scale sustainably.
