First, your structure is not compatible with the result you need to achieve. To optimize scalable code structure, imagine millions of people using your application. Imagine several front-end applications making requests to the back-end, and vice versa. Therefore, understand who needs a scalable backend. The great structure you code today is not compatible with that. Today you use a backend with msqlite architecture, validation with Zod, and Vite on the frontend. In short, your code is a big mess, a poor structure. If you imagine an app with millions of people using it all day, you will need an app with a good structure, easy to maintain, so you can hire people to work on it. I usually opt for an architecture using NestJS on the backend and Next.js on the frontend, because this combination offers: greater security, with controlled APIs, robust authentication and a clear separation of responsibilities; and high scalability, since both frameworks are prepared to handle large volumes of data and multiple simultaneous users. Optimized static content, using Next.js to serve pages and information that change little (SSG/ISR), improving speed and saving server resources. Reliable transactions, since in the backend (NestJS) I centralize all validation, business logic and secure processing — this reduces failures and ensures consistent feedback to the user in each operation. Easier maintenance, with modular code split between API (NestJS) and interface (Next.js), allowing the system to evolve continuously. This stack is my choice when quality, performance and security are essential from the start of development. Cloud choice depends on the project's needs, but generally deployment is fast, secure and easily monitored to ensure stability and frequent updates. In this approach, I develop a decoupled application structured in modules, which brings several advantages: easier code maintenance, a data layer decoupled from business logic (allowing the use or replacement of any database) and clean integration of new services. The application is secure and follows coding best practices, based on object-oriented programming principles. Using the NestJS framework, we can structure the whole ecosystem into isolated modules, each with clearly defined internal and external layers. This results in a clean architecture, high scalability and readable, easy-to-maintain code. If you need a scalable database, one option is MongoDB. I use immutable methods: the application never modifies historical records — instead it creates new instances/versions. For example, if a user starts as an author and later becomes a regular user and performs an operation, we do not change the previous record; we add a new event/entity representing that change. This preserves an auditable history and prevents data loss. Functions are reactive and operations are atomic: for local operations, we use ACID transactions (all-or-nothing). For distributed flows, we use orchestration/compensation patterns (sagas) or Event Sourcing (append-only) when appropriate. During a workflow, we collect possible errors; at the end, if each step succeeds, we persist the new instance/event; otherwise, we roll back/compensate and return the aggregated errors. I recommend using append-only/Event Sourcing + CQRS only for systems that require immutable history and state reconstruction. This system should run only on Linux environments. Do not run it directly on Windows. This can cause filesystem discrepancies and even data corruption. There is an external layer and an internal layer. The external layer hosts generic APIs and integrations with third-party systems (for example, payment providers). The internal layer contains controllers, middlewares and services, implemented with dependency injection using Nest. Each request is handled by services, models and providers, each representing a table or aggregate in the database.

I help companies transform ambitious ideas into high-performance, scalable software. Whether you're a startup launching an MVP or an established business optimizing a complex system, I provide the strategic blueprint for success. As a seasoned software consultant, I specialize in the intersection of business strategy and technical execution. My consulting approach focuses on: ✅ Software Development Strategy & Consulting ✅ Technical Architecture & System Design Review ✅ Project Scoping & Requirements Definition ✅ Agile/Scrum Process Setup & Optimization ✅ Digital Marketing for Product Growth If you're looking for an experienced partner to help you plan, refine, or rescue your software project, let's connect. I'm ready to help you build better.

Senior iOS engineer with 12+ years of experience building high-scale, consumer-facing apps used by millions. Deep expertise in Swift, UIKit, RxSwift, and modern mobile architectures. Proven track record leading complex feature development, improving performance, and shipping polished, intuitive user experiences. Founder of multiple successful apps, combining strong product thinking with technical excellence.

Starting college, genetic engineering was my passion, but I couldn't stand the idea of a company or university owning my intellectual property outright after I had worked so hard on it. So I decided I needed to open my own genetic engineering lab. Not surprisingly, I didn't have the money for such an endeavor, but being the age of the mobile app, and seeing how profitable a well-made app could be, I decided software development would be a stepping stone towards my lab. For a couple of years, I just compiled ideas and continued with my genetic engineering major. Then in February 2016, with no programming background, I started developing my first app. I dropped everything I was doing, school included. 14 hours a day, and a year and a half later, I was a competent Android, iOS, and web-infrastructure engineer. It's been some time since then, and mobile app development — primarily iOS — has been my sole focus ever since. I've come a long way and have gotten to the point where my time is best spent developing my own ideas rather than taking up employment at Big Tech. That said, developers got to eat too, so while my passion project is still in development (mobile app), I've decided to take up freelancing to make a living; for both the extraordinary people and projects it affords me the opportunity to get involved with.

✅ Worked over 2500hours and around 90 projects ✅ 100% Client Recommendation ✅ 5 Star Feedback ✅ Fluent English Verified I am Full stack Senior web developer having over 10years of software development experience. I am very good at understanding customer problems and gives the best possible cost-effective solution. I have worked on SaaS products, Marketplaces, Healthcare, Insurance, Stock Markets, Health Apps, Travel App, Marketplace appA, etc Tech stack which I am excited to work Frontend - React: Redux, Mobx, Hooks, Gatsby, Next, Redux-form, Formik, React Query - React Native, React Native Navigation, BLE communications, etc - Vue: Vuex, Vuetify, Vue-Router, Mixins, Nuxt Backend: - Node.js, Express.js, Serverless - PHP, Laravel, Symfony, Codeigniter - Python, Django Database: - MySQL - MongoDB - Postgres - DynamoDB Cloud: AWS: EC2, S3, Lambda, Elastic Beanstalk, DynamoDB, Cognito Firebase: Firestore, Real-time Database, Hosting, Cloud functions, Crashlytics, Cloud Messaging, AWS Codebuild, AWS Codepipeline Tools: Vite, Webpack, Gulp, Babel, Git, Asana, Jira, Docker, Kubernetes

Mobile products succeed when product judgment, engineering quality and delivery accountability stay under one owner. 12+ years of mobile engineering experience across fintech, payments, SaaS and mass-market consumer products. Proven track record of building greenfield applications, modernizing complex codebases and leading engineering teams of up to 8 developers. Selected experience: • Led iOS delivery at IBTECH, QNB Finansbank's technology arm • Built GSPara and Fenerpara wallet products serving 150K+ monthly active users • Shipped payment and account features for QNB Mobile, used by 4M+ customers • Led two greenfield mobile products from architecture through production release for international SaaS teams • Delivered products for Garanti BBVA, Akbank, N11 and BiTaksi Core delivery areas: • Mobile-first MVP development • Native iOS development with Swift, SwiftUI and UIKit • iOS, Android and React Native product delivery • Mobile applications for existing web and SaaS platforms • Existing app audits, stabilization and rebuild planning • API, payment, Firebase and third-party integrations • CI/CD, automated testing and release readiness • Technical planning, team leadership and delivery ownership Hands-on expertise is strongest in Swift, SwiftUI and UIKit. Broader end-to-end mobile delivery across iOS, Android and React Native is led through Pallasite, an Estonia-based product and engineering company. Every engagement begins by reducing uncertain requirements to a focused product scope, clear milestones and measurable release objectives. Delivery includes regular product reviews, transparent communication, maintainable source code, tested builds and complete handover. Best suited for founders and product owners looking for a senior technical partner who can challenge assumptions, make pragmatic decisions and remain accountable from initial scope through production release.

As a Senior UI UX Designer, I work at the intersection of product strategy, UX research, interaction design, and visual design. Every Web Design project and Mobile App Design engagement starts with understanding business goals, user behavior, and product vision before creating solutions that drive measurable results. I don't simply create interfaces, rather, I take ownership of the entire product lifecycle. From product discovery and UX strategy to wireframes, prototypes, high-fidelity UI, design systems, usability testing, and developer handoff, I help teams launch successful products. Whether it's a SaaS platform, a responsive Web Design project, or a complex Mobile App Design, my focus is always on building products that scale. My experience as a Senior UI UX Designer includes designing: • Enterprise SaaS platforms • Modern Web Design solutions • iOS & Android Mobile App Design • FinTech and banking products • Healthcare applications • AI-powered platforms • Marketplaces and eCommerce products • Dashboards and management systems I actively leverage AI throughout my design process to accelerate UX research, ideation, competitor analysis, wireframing, prototyping, and validation. AI helps me iterate faster, but successful Web Design, Mobile App Design, and SaaS products still require thoughtful product strategy and human-centered design. Industries where I deliver exceptional results 💰 Financial & Banking Services 📊 SaaS Platforms 🪷 Wellness, Fitness & Mindfulness 🖥️ Corporate Web Design 🏠 Real Estate Platforms 🏥 Healthcare & MedTech 📚 E-commerce 🚚 Logistics & Transportation 🚸 Education & EdTech ❤️ Social & Community Apps 🍾 Premium & Luxury Digital Products Over the course of my career as a Senior UI UX Designer, my work has reached 60M+ users across 30+ countries, helping companies validate ideas, launch MVPs, redesign existing products, improve conversion rates, and scale internationally. My expertise includes: ✔ Senior UI UX Designer ✔ UI UX Design ✔ UX Research ✔ Web Design ✔ Responsive Web Design ✔ Landing Pages & Websites ✔ Mobile App Design (iOS & Android) ✔ Product Design ✔ SaaS Product Design ✔ Enterprise SaaS Platforms ✔ Design Systems ✔ Figma Expert ✔ Wireframing & Prototyping ✔ User Flows & Information Architecture ✔ Usability Testing ✔ Developer Handoff If you're looking for a Senior UI UX Designer who combines strategic thinking with world-class Web Design, intuitive Mobile App Design, and extensive experience building scalable SaaS products, I'd be happy to help bring your product vision to life. Mateja Bartolovic

I’m a Senior Mobile App Developer with 10+ years of experience delivering high-quality, scalable mobile applications using Flutter and FlutterFlow. I specialize in building modern, responsive, and performance-optimized cross-platform apps for both Android and iOS. Whether you're looking to launch an MVP, modernize an existing app, or integrate backend systems, I can help bring your vision to life with clean architecture and intuitive UI/UX. My focus is on delivering production-ready apps that meet both user and business goals. I work closely with clients to ensure transparent communication, efficient development cycles, and timely delivery. Let’s create something exceptional!

SUMMARY * Senior technology leader (CTO/Engineering Manager) with 20 plus years of experience scaling SaaS, cloud, and mobile products. * Hands-on player-coach skilled at guiding teams, implementing agile processes, and driving innovation from concept to acquisition. * Proven success in cost optimization, cloud infrastructure (AWS), security compliance, and crossplatform development. * Strong collaborator with executives and founders, translating product vision into scalable technology solutions. KEY ACHIEVEMENTS Enhanced Downtime Management Reduced production downtime by 100% with sandboxed testing. Expanded Market Reach Improved dealership reach by 50% through thirdparty integrations. Scaled User Support Created applications that supported 50,000 plus users with 100s of terabytes of data across 1,000 plus auto dealerships using AWS.

Most agencies promise fast delivery. Few have built for Pizza Hut, IKEA, Mercedes-Benz, and Verizon. I work with founders and product leads who need a real technical partner someone who takes ownership of architecture, build, and deployment end-to-end. Not a freelancer who waits for tickets. What I have shipped: CallIQ — AI revenue intelligence platform connecting Google Ads to inbound phone calls using GPT-4o for transcription and intent classification. Built for home services, dental, legal, and automotive verticals. PosPAL — Multi-tenant POS platform for cannabis dispensaries and retail across Oregon and Washington. Integrated NMI, Aeropay, Metrc API, and AAMVA ID verification. Enterprise Platform Suite — 6 white-label platforms for a UK commercial vehicle broker. React, Next.js, Node.js, PostgreSQL. Contract value 135K GBP. Fractional CTO retained post-delivery. Orbit — AI image generation platform for advertising creatives integrating Leonardo.ai and Claude vision models for saliency-based text composition. What I build: MVP and SaaS platforms from scratch. AI integrations using GPT-4o, Claude API, LangChain, and n8n. Mobile apps in React Native and Flutter. Enterprise workflow automation. BI and analytics platforms. Our stack: React, Next.js, Node.js, Python, FastAPI, PostgreSQL, Supabase, Firebase, LangChain, n8n, vector databases, Twilio, Stripe, AWS, GCP, Azure, Docker. We do not take bug fixes, quick tasks, or staff augmentation roles. Our sweet spot is fixed-price builds of 5K to 25K USD and scoped AI integration contracts. If you are building something that needs to work talk to me.