Senior Product Engineer · SaaS & AI Development · AI-Assisted Development

Building scalable software that grows with your business

I help SaaS companies build and scale web products end-to-end — from launching MVPs and adding new features to modernizing products that become harder to maintain as they grow.

Worked with

Paayed
Inditex
FinQuery
Symphony
Devtech
Nulia
Fitcher
Paayed
Inditex
FinQuery
Symphony
Devtech
Nulia
Fitcher

The Person Behind the Code

Get to Know Me

Petar Jovanovic

7+

Years of experience

3

Startups built from ground up

10+

Production projects

100K+

Users impacted

Hi there! I'm Petar, a Senior Product Engineer and technical partner. I'm here to help you build or evolve your SaaS product end-to-end — one that solves the right problem, feels effortless to use, and can grow from user #1 to user #1,000,000.

I've spent the last 7+ years building products across startups and large enterprise environments, including platforms for Fortune Global 500 companies, spanning fintech, ed-tech, social networking, and e-commerce.

That experience has taught me that the best software comes from understanding the problem before writing the solution. Before thinking about implementation, I want to understand the problem we're actually trying to solve. Who is using the product? Why do they need this feature? Is there a simpler way to achieve the same outcome? And will the decisions we make today still make sense as the product grows?

That's the mindset I bring to every project.

I especially enjoy the challenges that come with growing SaaS products. What starts as a simple application naturally becomes more complex as customers, features, and requirements accumulate. Patterns that worked at the beginning stop scaling. Development slows down. Small changes start affecting unexpected parts of the product.

I enjoy stepping into that complexity, understanding what's causing it, and finding ways to make the product easier to build, maintain, and evolve.

That mindset shaped some of the work I'm most proud of. Most recently, at Paayed, a UK-based B2B fintech SaaS platform, I saw that an inconsistent UI and duplicated frontend patterns were becoming increasingly difficult to maintain as the platform grew. I built a shared component library and design system that was adopted across the product, giving the team a stronger foundation for developing new features and evolving the platform.

I'm also someone who cares about the small details. Whether it's an interaction that doesn't quite feel right, an unnecessarily complicated piece of code, or an architectural decision that could create problems later, I find it difficult to simply say, "good enough." I want to finish something and genuinely be proud of what I've built.

AI has made building software faster than ever, and I use it extensively in my own development process. But I think that makes engineering judgment even more important. The interesting question is increasingly not "Can we build this?" but "Should we build this — and what's the simplest way to solve the actual problem?"

Outside of client and product work, I'm building What Is The Output, my own experiment in making developer education more personalized. Building something of my own has given me another perspective on software — thinking not only about architecture and code, but also about users, validation, priorities, and whether an idea actually creates enough value to deserve being built.

And when I'm away from the keyboard, you'll usually find me playing music, reading, or spending time with my family.

So if you're building a SaaS product and looking for an engineer who will understand the bigger picture, care about the details, contribute ideas, and take ownership beyond the code itself — we'll probably have a lot to talk about.

My values

Meticulous

Whether it's an interaction that doesn't feel right, an overly complicated piece of code, or an architectural decision that could cause problems later — I find it difficult to simply say 'good enough.' I want to finish something and genuinely be proud of what I've built.

Transparent

I surface concerns early rather than staying quiet and letting them grow. I value clear, honest communication — about what's working, what isn't, and what decisions we're making and why.

Problem-first

Before thinking about implementation, I want to understand the actual problem. Who is using this? Why do they need it? Is there a simpler way? The question is no longer 'Can we build this?' — it's 'Should we, and what's the simplest way to solve the real problem?'

Purposeful

I understand the bigger picture, contribute ideas, and take ownership beyond the code. I'm not completing a task list — I'm helping build a product that solves the right problem and can grow from user #1 to user #1,000,000.

Process

How we'll work together

01

Step 01

Analyze Your Requirements

Every successful product starts with understanding the problem. We don't start building until I fully understand every detail of your vision. I'll take the time to learn about your business, users, goals, and technical constraints before making any implementation decisions. The right solution begins with asking the right questions.

02

Step 02

Propose the Right Solution

Once I understand the bigger picture, I'll recommend an approach that balances business goals, technical quality, scalability, and development speed. Every decision is made with your product's long-term success in mind.

03

Step 03

Build with Engineering in Mind

This is where ideas become reality. I leverage AI to accelerate development, helping you validate your idea faster without compromising quality. Combined with clean architecture, maintainable code, thoughtful user experiences, and transparent communication, it allows us to move quickly while building software that's made to last.

04

Step 04

Launch & Keep Improving

Shipping isn't the finish line—it's the beginning. After launch, we'll gather feedback, measure results, iterate on what matters, and continue improving the product as it grows.

Selected Work

What I've built

Products I helped design, build and ship — for fintech startups, enterprise teams and Fortune Global 500 companies.

Fintech · B2B SaaS2025–26

Paayed — All-in-one B2B Fintech Platform

Payments, accounting and CRM for UK SMEs. I owned UI standardization, built the design system and shipped core payment and security flows.

90+legacy components replaced
Role
Product Engineer · Design System Owner
TypeScriptReactTailwindRadix UIJestRTL+1
Enterprise · Micro-frontends2022–24

Supplier & QA Platform for a Fortune Global 500 Fashion Company

Replaced manual production and quality-assurance processes between internal QA teams and a global supplier network with a Domain-Driven micro-frontend platform.

5+teams on my shared UI library
Role
Frontend Engineer
TypeScriptReactJestStryker.js+2
AI · Analytics · SaaS2021–22

AI-powered Microsoft 365 Enablement Platform

Led frontend for the advanced analytics version, turning complex requirements and large datasets into clear, interactive D3.js visualizations.

1000sof organizations served
Role
Frontend Lead · Data Visualization
TypeScriptReactD3.jsMaterial UI+1
Fintech · Enterprise2021–22

Enterprise Accounting Platform Modernization

Helped move a legacy US accounting platform to a scalable modern web architecture — complex onboarding, lease accounting and data-heavy reporting.

Legacy → Modernenterprise architecture
Role
Frontend Engineer
TypeScriptNext.jsRedux ToolkitRedux Saga+2
Marketplace · MVP2022–24

Service Booking Platform for the US Market

Took end-to-end technical ownership of a two-sided booking platform — architecture from scratch, service discovery, scheduling and secure auth.

0 → 1architecture & MVP
Role
Full-stack Engineer · Technical Owner
TypeScriptNext.jsPrismaPostgreSQL+4

Have a similar product in mind?

Testimonials

What people I’ve worked with say

Petar consistently took initiative and approached his work with a strong sense of ownership. His contribution to our component library and the standardisation of UI across the platform gave us a more consistent frontend, better reusability, and stronger foundations as we continue to scale. Proactive, collaborative, and genuinely invested in improving the product beyond the tasks assigned to him.
Libby Schlesinger

Libby Schlesinger

Founder & VP · Paayed

Petar was an outstanding software developer on our banking platform. He tackled technically demanding tasks with remarkable diligence, especially when standardizing our React components. His code reviews were consistently insightful and helped elevate the whole team’s quality.
Behrooz Shabani

Behrooz Shabani

Solution Architect & Tech Lead · Paayed

On Nulia, Petar took a leading role on the frontend of one of the most technically demanding parts of the product, turning complex analytical requirements and large datasets into clear, interactive experiences with custom D3.js visualizations. He solved hard problems independently while keeping the user in mind. Someone I could rely on to take ownership and deliver.
Nikola Mirkov

Nikola Mirkov

Tech Lead · Devtech

Petar worked as a React front-end developer under my lead on a fast-paced initiative for a leading name in the fashion industry. He handled his components reliably, collaborated effectively across the team, and helped us meet our target deadlines.
Branislav Stojiljković

Branislav Stojiljković

Principal Software Engineer & Tech Lead · Symphony

Petar excelled as a Frontend Engineer on multiple projects. His technical skills and attention to detail consistently resulted in user-friendly interfaces that exceeded expectations. A fantastic collaborator who communicates effectively and fosters a positive team environment.
Nikola Mladenović

Nikola Mladenović

Project Manager · Lioneve Media

My Services

How I can help

Build Your Product

From idea to production-ready software.

Whether you're validating a new idea, launching an MVP, or scaling an existing product, I will help you transform your vision into a scalable web solution with a strong technical foundation, clean architecture, and maintainable code. AI accelerates my development workflow—so you ship faster without compromising quality.

  • ✓Production-ready MVP or SaaS application
  • ✓Scalable architecture that grows with your business
  • ✓Faster time-to-market without sacrificing quality
  • ✓Clean, maintainable code built for long-term success

Technical Consulting

Solve the problems slowing your team down.

Need a second opinion on the front-end architecture, performance bottlenecks, scalability or some other type of complexity? I help teams identify root causes, make informed technical decisions, and define a clear path forward.

  • ✓Clear diagnosis of bottlenecks and technical debt
  • ✓Actionable architecture and performance recommendations
  • ✓Informed decisions on tech stack and tooling
  • ✓A defined path forward for your team

Modernize & Scale

Improve what already works.

Legacy applications don't always need a rewrite. I help teams modernize codebases, introduce scalable architecture, establish design systems, improve performance, and reduce long-term maintenance costs without disrupting product development.

  • ✓Legacy codebase modernized without service disruption
  • ✓Scalable architecture and established design system
  • ✓Improved performance and Core Web Vitals
  • ✓Reduced maintenance costs and technical debt

Trusted by teams at

Paayed
Inditex
FinQuery
Symphony
Devtech
Nulia
Fitcher
Paayed
Inditex
FinQuery
Symphony
Devtech
Nulia
Fitcher

Tech

Tools of the trade

Languages

TypeScriptJavaScriptPHP

Frontend

ReactNext.jsAstroTailwindRadix UIMaterial UIRedux ToolkitD3.jsSass

Testing

JestRTLStryker.jsStorybookVitest

Backend & Data

Node.jsPostgreSQLMySQLMongoDBPrismaFirebase

Infra & DevOps

DockerGitHub ActionsJenkinsViteWebpack

AI Tools

GitHub CopilotClaudeCursorGemini

Auth & Tooling

Auth0ESLintGitFigma

Let's Connect

Let's build something powerful together

Book a free discovery call. No sales pitch — just an honest conversation about your challenges and whether I can help.

  • 30-minute focused conversation
  • No obligation, completely free
  • Understand your challenges first
  • Get actionable insights either way

What I'm looking for

  • ›Senior frontend roles
  • ›Full-stack roles (Next.js or Node.js)
  • ›Complex products at scale
  • ›Teams that care about craft
  • ›Remote or hybrid (Serbia-based)

Response time

I typically respond within 24 hours. If it's urgent, mention it in the subject line.

Location

Niš, Serbia

UTC+1 (CET) / UTC+2 (CEST)