Catalin – Swift, Node.js, React Native

A tree adoption and reforestation platform (work in progress) where users adopt real, verifiable trees tracked via GPS, QR/NFC codes, photos, and maintenance history. As sole developer and product owner, Cătălin independently designed and built the full product end-to-end — web platform, admin system, backend API, and mobile field app.

• Acted as sole developer and product owner, owning the full product and technical direction of the platform and independently designing, building, and delivering features end-to-end (frontend, backend, mobile, and data model);
• Envisioned the core product concept — proof-first tree adoption with verifiable real trees — including the dual adoption model (pre-planting reservations with chronological assignment, and immediate adoption of already-planted trees), gift purchases with pending-ownership claiming, and corporate project sponsorships;
• Architected the domain and data model (PostgreSQL + Prisma) covering projects, species, trees, transactions, NGOs, sponsors, and tree updates, including project-specific species pricing and quantity tracking, project funding lifecycle (draft → published → funded → active → completed), and ownership/gifting rules;
• Built the Next.js web platform: public landing page with live impact statistics and project browsing, plus a full admin dashboard with a multi-step project creation wizard, species/NGO/sponsor management, and tree management with table and interactive map views;
• Built the Node.js/Express backend API with JWT authentication, role-based access control (user / manager / moderator / admin), web and mobile-specific REST endpoints, and data-integrity and validation rules (unique QR codes, availability limits, project–species consistency);
• Designed and built the QR/NFC proof system — backend code generation, physical tree labeling workflow, public scan-to-tree pages with privacy rules, and the field marking logic matching reserved trees to newly planted physical trees;
• Developed the React Native mobile app for field operations and public use: QR scanning, GPS capture, tree creation, watering logs, problem reporting with severity and moderation flow, and GPS-based nearby-tree discovery; designed the offline-first sync architecture with queued operations and conflict-resolution rules;
• Implemented full EN/RO internationalization across the platform (translatable projects, species, NGOs, and sponsors, with language-tabbed admin forms and fallback logic);
• Defined the brand direction and design system (proof-first positioning, tone of voice, color palette, typography, UI style) and the product principles guiding feature decisions;
• Owned product strategy and planning: business model design (adoptions, sponsorships, gifts, project-specific pricing), roadmap and MVP scoping, success metrics, and the risk and open-question register for legal, forestry, and carbon-related decisions.

An enterprise carbon accounting and GHG reporting platform used by several large, multi-location corporations, with AI powering both data import (automated invoice parsing) and reporting. As CTO and product owner, Cătălin independently designed and built full platform features end-to-end, along with the business automations built around it.

• Acted as CTO and product owner, owning the technical direction of the platform and independently designing, building, and shipping full features end-to-end (frontend, backend, and data model);
• Architected the multi-scope emissions engine (Scope 1/2/3) with a category structure mirroring the GHG Protocol, including a configurable calculation layer supporting multiple methodologies and emission factors per module;
• Built the multi-site data model enabling large corporations to collect, standardize, and consolidate emissions data across many locations, with data owners, validation steps, and approval workflows;
• Integrated AI into the data import pipeline, including automated invoice parsing to extract consumption data from unstructured utility documents, and into the reporting layer;
• Developed the reporting engine — web-preview and PDF generation, report versioning with validation-and-lock, plus interim and per-location report models;
• Implemented flexible Excel import/export (template-based and free-form) and a full audit trail linking every figure back to its source document and calculation method for assurance readiness;
• Designed and built the business automations around the platform (workflow and operational automations supporting the product and the wider business);
• Estimated and scoped features, set milestones and deadlines, and coordinated technical delivery with the founding team and collaborators;
• Proposed and evaluated architecture solutions for new capabilities and platform-wide improvements.

This is a Google Workspace plugin that uses AI (ChatGPT or Claude) to convert the user prompt into actions that it performs inside the spreadsheet. This was a showcase project for Catalin's AI skills.

• Created the Google scripts frontend and functionality;
• Prompt engendered the LLM request to provide the best response;
• Developed and deployed the backend.

This is one of the biggest players in the blockchain and metaverse ecosystem. Catalin was the technical lead for the inventory and marketplace part of the platform.

• Provided technical solutions for the asset upload, workspace, inventory, and market sections of the platform;
• Conducted audit of the NFT minting (and lazy imaging ) and transferred smart contracts;
• Improved the search response speed using elastic search;
• Refactored and cleaned up a large part of the code, both front end and back end;
• Estimated tasks and milestones, delegated tasks, set deadlines and clear goals, coordinated with team members, and synced with teams all around the globe (Argentina, Uruguay, France, Romania, China);
• Proposed architecture solutions for various tasks and improvements.

Honest dating and personal growth cross-platform mobile app. Uses AI to check for indecent photos and has a proprietary matching algorithm. Also includes a personal growth section.

• Architected and built the entire platform by himself;
• Built the backend with a focus on optimizing for cloud services costs while not sacrificing user experience;
• The app was hosting 10k users (500 daily average and 100 peek active at once). Cloud services cost under $100.

This is one of the largest course providers dedicated to people who want to do a reconversion in their career. It has offers in a lot of directions from business analytics to design and software development.

• Taught a class of 16 students of all ages (from 20 to 45) front-end development. 6 got hired in the industry after this course.

Excel + Powerpoint + extra functions all in the cloud. Started as a prototype but, because development was moving so fast, the client pivoted towards a full product. Build the MVP and the rest of the requested features moving towards a real serious product. Was the Team Lead when new developers arrived. The Senior Architect who took over the project was impressed with the speed of the system and the technologies stack used.

• Implemented 80% of Excel and 90% of PowerPoint functionality in a project hosted in the cloud;
• Implemented Google login;
• Created a scalable architecture focused on fast development (clients' former devs were also impressed by the performance of the system).

The platform offers barber services for customers at their desired locations.

• Built the mobile client used for booking barber appointments;
• Solo-developed a mobile app from scratch;
• Used existing GraphQL API.

A multi-vendor marketplace, like Amazon, centered on nature-inspired goods with a big focus on the user experience.

It was a client without a tech background, so Catalin was responsible for the entire development branch.

• Created a modular "microservices" inspired architecture (the client wanted to have the possibility to expand the platform towards video streaming, chat/dating app);
• Implemented the mobile client (the only developer) Team lead / main developer for the backend;
• Supervised and reviewed code for two junior developers;
• Supervised the frontend development and reviewed code written by the juniors;
• Was in charge of DevOps, deployments, and pipelines;
• Trained two junior developers to help/continue the project and was responsible for extracting tasks and subtasks, prioritizing, and creating estimations.

Live virtual campus tours that connect student guides with visitors from any part of the world.

• Created the architecture for the front-end part of the system;
• Coordinated part of the front-end team;
• Implemented part of the dashboard;
• Used low-code to build the landing page

iOS app that gathers restaurant reviews. The reviews were based on the user context and their older preferences. Used IBM Watson AI to generate recommendations.

• Was fully responsible for developing the mobile iOS and back-end parts of the application;
• Integrated React Native modules in a native iOS app;
• Implemented a Facebook crawler that would get the restaurants from a specific area.

A call-to-listen solution for small radios that don't have the power to broadcast across states. The user would call a phone line and listen to the radio broadcast.

• Implemented the iOS mobile application;
• Embedded React Native in an iOS App to provide chat functionality;
• Integrated a money transfer solution inside the app;
• Implemented an OGG audio encoder/decoder.