Senior Full Stack Developer · UI/UX · Product Creator

Websites, apps and products that sell from the first second.

  Click · 45 seconds · sound on

Meet your senior engineer

Hi, I’m Cosmina. I build websites, apps and products that convert on day one.

10+ years shipping software across enterprise banking, fintech, and SaaS — for banks, scale-ups, and founders. I write the code, I design the flow, I architect the system. One senior engineer, zero agency drag.

  • 40+ verbatim peer reviews · 8+ years (2018–2026)
  • 2 live products · Architect Dashboard & CNT Coach
  • Senior full-stack · React, Next.js, Node, TypeScript, Kubernetes
  • Remote EU/US · based in Romania
Manifesto

Stop scrolling.

If your website isn’t converting, your idea is still just an idea, or your projects feel out of control — you’re losing opportunities every single day. This is the 45-second message that explains exactly how I fix that, written in plain English so you can read it in 10 seconds. Or watch the video ↑

If any of this is you…

  • Your website isn’t bringing clients.
  • Your idea is still just an idea.
  • Your projects feel out of control.

You’re losing time. And you’re losing opportunities. Every single day.

I fix that.

I build websites and applications that perform — fast, clean, and built to convert. No delays. No excuses. No wasted time.

And if you’re an architect or leader dealing with constant overload — I built Architect Dashboard to fix that too. No confusion. No chasing updates. Just control. Just results.

So fix it. Or stay stuck. Your call.

Three doors. Same phone. Pick the one that stops the bleeding today — or keep watching opportunities walk past. Your move.

Recognize this?

Recognize this moment?

If any of these sounds like your week — you’re not alone, and you don’t have to keep spinning. Every founder, coach, and leader below has sat exactly where you sit now. The fix starts with naming the moment out loud — then picking the service that actually solves it, not the one that sounds fanciest.

Website not converting

Your site doesn’t bring clients

Pretty design, no buyers. Bounce rates high, conversion flat. You know the problem isn’t traffic — it’s trust, speed, clarity. You need a site that closes on day one.

→ Web builds that sell

Product feels flat

Your product feels “meh”

Users land, look around, leave. The UI feels cheap, the flow feels broken, the pricing feels hard to justify. You don’t need more features — you need a redesign that makes visitors pull out the credit card.

→ UI/UX redesign

Overloaded leader

You’re busy but not productive

Leader, architect, founder — you’re chasing updates, losing track, burning energy on the wrong things. You need a dashboard that shows the truth in 2 minutes, not a 200-slide strategy deck.

→ Take the 2-min Quick Quiz

Services

Five ways to turn your product into revenue

One senior engineer, under one roof: code that ships, design that converts, architecture that scales. No agency drag, no junior rotations, no 80-slide decks that gather dust. Pick the path that matches where you are right now — from first-time founders launching their MVP to scale-ups that need a second set of senior hands. Every engagement starts in weeks, not months.

Web builds

1 · Web builds — ship a product that sells on day one

MVPs and production web apps that don’t just ship — they close. Premium UI from the first pixel, bulletproof architecture from the first commit, copy that converts. Launch in weeks, not months, and hit the market ready to sell at a premium price.

For founders ready to launch. Outcome: live product, paying customers.

→ Discuss your build

UI UX design

2 · UI/UX — turn “meh” into “take my money”

Premium redesigns and conversion-first UI systems that make visitors pull out the credit card. Figma design systems, real user flows, and copy that sells — not just pretty screens. Your product finally looks as expensive as it is.

For products that underperform their price. Outcome: higher conversion, higher pricing.

→ Redesign my product

Maintenance retainer

3 · Maintenance — your product, kept sharp and fast

Senior engineering on call, every month. Bugs fixed before customers see them, performance kept in the 90s, accessibility locked in, new features shipped weekly. Sleep at night while your product compounds — no more firefighting, no more flaky freelancers.

Monthly retainer. Outcome: zero downtime, compounding speed.

→ Start the retainer

Senior Full Stack Developer

4 · Full Stack Developer — senior delivery at 30% of the cost

Two days a week of senior full-stack delivery — roadmaps, code, architecture reviews, hiring standards, unblocking your team — for 3–6 months. You get a staff-level engineer’s judgment without the €175K full-time comp, the 6-month hiring cycle, or the risk of a bad hire.

€20–50K · 2 days/week. Outcome: clear roadmap, team unblocked.

→ See investment detail

Technical advisory

5 · Advisory — don’t spend six figures before this call

Hourly calls, brutally honest go/no-go reviews, and sharp second opinions before you commit to a build, a hire, or a vendor. One 90-minute session can save you months of wrong direction and tens of thousands in wasted budget.

Pay by the hour. Outcome: right decision, less burn.

→ Book a 90-min session

Not sure which fits?

30 minutes, sharp questions, an honest recommendation. No agency pitch, no upsell, no time wasted. I tell you which of the 5 makes you money fastest — even if it’s none of them.

Book the 30-min call

My Products

My own products — live, shipping, paying

Two live products running in production, with real customers and real uptime. I don’t just advise — I eat my own cooking. Architect Dashboard diagnoses where your energy leaks and returns a plan in 2 minutes. CNT Coach + CoachMind gives coaches a real tool instead of handwritten notes. Try either, free, before we ever talk.

  Architect Dashboard

For leaders burning out

You feel exhausted, low energy, unproductive — even though you’re busy every minute. The team feels it too: stagnation, disengagement, slow delivery, passive-aggressive noise.

The platform

  • Quick Quiz — 2-minute diagnostic: where your energy leaks & what to do about it.
  • Deep Quiz — 8-minute leadership blind-spot analysis tailored to your profile.
  • TEAMS — 5-question team diagnostic (up to 10 members, private invite) to surface true group tonus.
  • Dashboard — monitor progress, set objectives, visualize performance over time.

Start free

  • First 3 quick quizzes are free. 27€ per full profile after that.
  • No email wall for the first quiz. 2 minutes. Answer in full.

  CNT Coach & CoachMind

For coaches & coachees

You’re facing an emotional block and want a clear development plan — a safe space to communicate, connect, and discover your potential. Or you’re a coach tired of handwritten notes and want real structure, clarity, and a visible trajectory from first to last session.

Two paths

  • 1:1 Coaching — with Cosmina, CNT-certified. Safe space, honest reflection, concrete plan.
  • CoachMind — a digital assistant for coaches: roadmap builder, client evolution tracker, session memory. No more handwritten notes.

Engineering rigor in a warm space

  • Clear trajectory from first to last session
  • Structure & clarity without losing the human part
  • Free 30-min discovery call on Calendly

Case Studies: Real Problems, Real Results

Real projects, measurable numbers, documented trajectories. Every case study below shows the starting pain, the mechanism I used, and the outcome you can verify. No vanity metrics, no hand-wavy “strategic impact” — just what was broken, what I built, and what it moved.

Work

How I Work

A four-step rhythm that respects your runway and your time. Week one is free discovery — no open-ended retainer, no scope creep, no surprise invoice. Everything is scoped, priced, and milestoned before you write the first check. You stay in control. I stay in output mode. Weekly demos keep both of us honest, and a clean handover makes sure your team can keep running without me.

1

DISCOVERY

Week 1

  • 30-min intro → 2h assessment
  • Audit architecture, interview team
  • Output: 20-page System Assessment
2

PROPOSAL

Week 2

  • Problems ranked by impact
  • Solutions with timeline
  • Investment proposal
  • You decide: Go/No-go
3

EXECUTION

Months 1-6

  • 2 days/week (Mon + Wed)
  • Hands-on (I code, not just advise)
  • Weekly updates, pair programming
  • Result: Foundation built
4

HANDOFF

Final Month

  • Documentation complete
  • Your team trained
  • Monitoring established
  • Optional: Monthly retainer

Investment

Transparent anchors. Most engagements land between €20–50K — the final number depends on scope and timeline, not on how fast you blink in the discovery call. No “phase 2” bait-and-switch, no hidden revision fees, no retainer creep. You see the number before you sign.

Senior Full Stack Developer (Fractional)

Engagement: 2 days/week × 3-6 months · Code + UI/UX + architecture

Typical investment: €20-50K

(varies by scope & complexity)

vs.
Full-time Senior Developer
€120K + benefits + recruitment

You save 60-70%

Frequently Asked Questions

The real questions people ask before committing — answered in plain English, without lawyer-speak or sales gymnastics. How do I compare to a full-time hire? What if you don’t know my stack? Do I sign NDAs? It’s all here. If something’s still unclear, 30 minutes on a call closes the gap — no commitment to ask.

Cost: Full-time senior developer = €120K + €40K benefits + €15K recruitment ≈ €175K/year. Fractional ≈ €48K/year (73% savings).

Speed: I start in 2 weeks. Full-time hire takes 3-6 months.

Flexibility: Scale up/down as needed. No firing awkwardness if priorities shift.

Best for: Companies that need senior full-stack execution but not 40 hours/week of it.

My specialty: Systems thinking, not language-specific coding. I've worked with Node.js, Python, Java, PHP, Go across banking, fintech, e-commerce.

What matters: Architecture patterns (microservices, event-driven, CQRS), security principles (OWASP, zero-trust), infrastructure (Kubernetes, cloud, CI/CD) are universal.

Learning curve: I get productive in new codebases within 1 week. Your patterns/frameworks in 2-3 weeks.

Yes, always. Standard mutual NDA before discovery call. Happy to review your template.

What I protect: Your architecture docs, code, business logic, customer data, roadmap.

What I share (anonymously): General lessons in blog posts (e.g., "How to migrate to Kubernetes" without naming clients).

Consulting firms: Send junior consultants (€800-1,200/day) supervised by senior partner you never meet. Deliver PowerPoint decks, not code.

Me: You work directly with me (no juniors). I write code, not just strategy docs. Hands-on implementation, not just advice.

Also: No upselling. No "phase 2" bait-and-switch. Fixed daily rate, transparent scope.

Short answer: Not my focus, but I can help indirectly.

What I do: Train your existing team, document systems so they self-serve, pair program to upskill juniors.

What I don't do: Conduct interviews, write job descriptions, manage performance reviews, be a line manager.

If you need that: You need a fractional CTO/Head of Engineering (different role). Happy to refer specialists.

Flexible options:

  • 3 days/week: Available for critical projects (e.g., pre-funding security audit, urgent migrations)
  • Full-time sprint: 4-6 weeks for intensive buildouts (rare, scheduled months ahead)
  • Team scaling: I can bring trusted contractors for execution while I handle architecture

Typical pattern: Start 2 days/week → spike to 3 days during critical phase → drop to 1 day/week for maintenance.

Still have questions? Book 30-min call

Reviews

What managers and teams actually wrote

Real words from real managers and teammates — not hand-picked testimonials written by a copywriter. 40+ verbatim reviews over 8+ years (2018–2026), across enterprise banking, fintech, and SaaS. Sources anonymized out of respect for NDAs, but every quote is word-for-word.

“Over the last 3 months you managed to solve many problems for the teams and on top of that help with problems that were not even on our chart. You currently are the go-to person for the wider organization.”

Engineering Manager

Enterprise Finance · Security & Delivery · 2023

“Cosmina is without a doubt one of the most energetic, enthusiastic members of our organization. She brings a level of commitment that is unparalleled — a real asset in any role where attention to detail, perseverance and determination are needed.”

Product Manager

Pre-trade Platform · React framework

“She consistently breaks down tricky issues and gets things done efficiently. More than just her coding skills, she’s been a great teammate who’s always ready to help others. Having her on the team really boosts everyone’s productivity.”

Senior Developer

Financial Services · Application development

“Her focus and drive for personal-growth made her highly adaptable and not afraid to dive into unknown Angular or React codebases. Curiosity-driven mindset, an extraordinary ability to connect, and always focused on going beyond her limits.”

Direct Manager

Global SaaS Platform · Machine Learning · 2020

“Cosmina has been one of the best team leads it was my pleasure to work with. She always brings the right expertise to deliver great results, listens to product owners, and implements the good ideas.”

Colleague · Same team

Retail Banking Platform · 1+ year

“It is very easy communicating with her, things are so straight forward. It makes you want to push yourself more and be better at what you are doing just talking or working with her.”

Colleague · Different team

Cross-team observation · 2021

“Through her curiosity and engagement, Cosmina has quickly become a key player for different projects spanning multiple teams. Any team would be lucky to have her.”

Colleague · Different team

Global SaaS Platform · Cross-team · 2020

“We worked together for Raiffeisen Luxembourg in 2016 — a very challenging project, handled very professionally. Excellent listener, easily connecting with people, highly talented front-end developer.”

Colleague · Same team

European Bank · Edge Connect · 2016

“You’ve been more deliberate in ensuring no unexpected issues arise from your changes — reduction in known QA issues. You’ve delivered technical presentations (SonarQube, Security, Aura) to attendees outside your immediate team.”

Senior Engineer

Investment Bank · Application Security · 2023

“You improved a lot — got to know our products better, helped a lot with styling and infrastructural things like OSS, AURA package updates. Good in digging into issues where it seems there is no solution; you will find it.”

Colleague · Same team

Investment Bank · 2-year collaboration

“High determination in doing the job right, problem-solving skills, management and organization skills — demonstrated in daily tasks and in communication with others.”

Colleague · Same team

Investment Bank · Daily collaboration · 2023

“For any non-compliance identified on SAST, Open Source, Server or Crypto, Cosmina takes ownership, prioritizes and delivers on time. She works closely with central governance, RTB, DevOps and App Security to triage and resolve.”

Senior Manager · Central Governance

Investment Bank · Compliance SME · 2023

“Your problem-solving and debugging skills have been outstanding. Your ability to focus on a problem, analyze it, and come up with effective solutions is truly commendable. It consistently contributes to the success of your team’s productivity.”

Manager · Different team

Investment Bank · Cross-team · 2023

“The key improvement has been representation of ROSE for security issues — you are now the go-to person for the group, and you’re extending that reputation to other groups, helping other teams out.”

Direct Manager

Investment Bank · Security & DevOps · Dec 2023

“You really stand out on the DevOps side. You’ve grasped a variety of knowledge that is obscure to most members of the team — and willing to share it both formally (presentations, Confluence) and informally.”

Senior Engineer

Investment Bank · DevOps SME · Dec 2023

“You have made noticeable upgrades to the team’s SDLC processes — improving UI package security compliance, investigating GitLab actions, monitoring QA migration to compute fabric. Your role: SDLC & DevOps subject matter expert.”

Direct Manager

Investment Bank · SDLC & DevOps · Jan 2024

“Autonomous and manages tasks without much intervention. Very collaborative — works with multiple teams to reach common goals. Overall, it is a pleasure working with an individual like herself.”

Manager · Same team

Investment Bank · Jan 2024

“You’re more open to challenges and willing to learn new things — solving more complex issues. In football terms I would describe you as ‘attacker’. You’re on the front lines in the wide meaning of this sentence.”

Colleague · Same team

Investment Bank · Jan 2024

“You currently are the go-to person with all of our Infrastructure teams. Your role is between UI developer and DevOps person — and you can decide how to progress.”

Direct Manager

Investment Bank · CARA → ROSE · Jan 2024

“Her strength is she is on top of her issues. Always keeps everything up to date and keeps track on it. She understands what needs to be done and does it quickly.”

Colleague · Different team

Investment Bank · Cross-team · Feb 2024

“You’ve taken ownership of the migration to compute fabric and effectively aided the team in the appcode migration (TBY0 → J300) for all our applications and connected systems. Your role: DevOps & SecOps subject matter expert.”

Senior Engineer

Investment Bank · DevOps & SecOps · May 2024

“You have full control over security — what takes it off from the team. The team can always count on your help in solving various issues.”

Colleague · Same team

Investment Bank · Security Master · May 2024

“You’ve successfully completed the first application Helios pipeline for DEV & QA. You continue to expand your knowledge of key tools in other areas of DevOps (e.g. CI/CD).”

Senior Engineer

Investment Bank · Helios + Compute Fabric · Aug 2024

“You assisted with the migration preparation of our application UIs (Data & Notes) to the cloud. You especially keep the team informed of new updates within the wider tech organization (GitHub Actions, Copilot etc.).”

Senior Engineer

Investment Bank · Cloud Migration · Nov 2024

“Open person, brave to speak out when something is unclear. A person going for their goals — when stepping out in meetings to clarify things that are ambiguous.”

Colleague · Same team

Investment Bank · Nov 2024

“From the onset, she gave the impression of a dependable, thoughtful and knowledgeable teammate. She’s proven herself to be someone willing to take on challenges and acts as a wonderful team player.”

Senior Engineer

Investment Bank · Multi-year collaboration

Showing 6 of 26 verbatim reviews  ·  8+ years (2018–2026)

Read newer reviews on LinkedIn →
Portfolio

Technical Execution: Selected Work

Selected work from the past decade — full-stack builds, UI/UX redesigns, and product experiments shipped for real users. Not mockups. Not Figma-only. Not agency-style “case studies” with stock photos. Real codebases, real traffic, real lessons learned the hard way. Click any tile for context, stack details, or the live link.

More Works
Let’s talk

Let’s talk — ready to build, redesign, or stabilize your product?

Three ways to start, zero pressure. If you’re just curious — take the 2-minute quiz, it’s free and brutally honest. If you have a real question — book 30 minutes and I’ll give you a concrete direction, not a sales pitch. If you prefer writing instead of talking — email me directly. Whichever you pick, I reply in one business day.

Step 1 · 2 minutes, free

Take the Quick Quiz

Feel exhausted, unproductive, busy but not moving? In 2 minutes you get a diagnostic + action plan. No email wall on the first quiz.

Take the 2-min quiz →

Step 3 · One reply

Send a private note

Prefer writing? Email me directly. I reply in one business day with a concrete next step — not a sales sequence.

Email Cosmina →

This is a good fit if you:

  • Need a site, app, or redesign that feels premium enough to justify the price
  • Want visitors to trust your offer faster and say yes sooner
  • Need senior direction before wasting money on the wrong build
  • Have an existing product that needs polish, speed, clarity, or stronger UX
  • Want hands-on implementation, not vague strategy and pretty decks
  • Value quality over speed — and revenue over vanity metrics