Vasile Adrian Rosian, Developer in Alba Iulia, Alba County, Romania
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Vasile Adrian Rosian

Verified Expert  in Engineering

Software Developer

Alba Iulia, Alba County, Romania
Toptal Member Since
October 27, 2015

Adrian is a web developer who has been working as a freelancer since 2008 with a focus on eCommerce and payment methods. He is an expert in developing efficient digital solutions for businesses with a focus on software correctness and maintainability.


Amazon Web Services (AWS), Amazon Cognito, AWS Lambda, Amazon Neptune, Redis...
Babes-Bolyai University of Cluj-Napoca
C++, .NET, Java, Parallel Programming, Operating Systems, Compilers...
WhiteCity Code SRL
Computer Vision, ClojureScript, Elm, Haskell, Clojure, Erlang, Raspberry Pi...




Preferred Environment

Docker, Git, Vim Text Editor, Fedora, Haskell, Clojure

The most amazing...

...insightful book I've read was SICP, as it opened my mind to functional programming.

Work Experience


2019 - PRESENT
  • Developed the architecture of the system based on cloud microservices.
  • Scripted some of the API interactions using Haskell.
  • Reviewed most of the Haskell code integrated into the platform.
  • Deployed the entire infrastructure on AWS via Terraform.
  • Wrote the CI/CD GitLab pipelines for deploying environments.
  • Reviewed makefiles for the local infrastructure deployment, including builds in Docker for TypeScript and stack builds for Haskell.
  • Wrote the lambda functions in Haskell with Dhall configurations and common libraries built in the same stack project.
Technologies: Amazon Web Services (AWS), Amazon Cognito, AWS Lambda, Amazon Neptune, Redis, Docker, GitLab CI/CD, Amazon API Gateway, Amazon CloudFront CDN, Amazon Simple Notification Service (Amazon SNS), Amazon Simple Email Service (SES), Haskell, TypeScript 3, Vue, GraphQL, Apollo, Terraform, DevOps, TypeScript, Material UI, Git, APIs, Node.js, Microservices, Technical Architecture, Leadership, eCommerce, Technical Consulting, REST APIs, CI/CD Pipelines, Agile, Back-end

Associated Teaching Assistant

2018 - PRESENT
Babes-Bolyai University of Cluj-Napoca
  • Conducted formal language and compilation techniques, lab assistance, practical teaching, and evaluation of students.
  • Worked on operating systems and practical knowledge, along with teaching and evaluation.
  • Handled parallel and distributed computing practical teaching and evaluation in C++, C#, and Java.
  • Presented object-oriented programming practical teaching and evaluation in the C++ language.
  • Practiced software engineering techniques, practical teaching, and evaluation, from software development process management to planning and executing initial software development stages.
Technologies: C++, .NET, Java, Parallel Programming, Operating Systems, Compilers, Object-oriented Programming (OOP), Software Engineering, C#, Agile

Project Manager

2017 - PRESENT
WhiteCity Code SRL
  • Built a receipt reading app; involved a Python prototype, OpenCV, and an iOS app. It used the camera and shared extensions with Facebook authentication/registration. The server side was in Haskell with Servant with SQL and Google API integration for OCR.
  • Developed from scratch a Clojure chat app and added functionalities as needed. Tech-wise it involved Clojure with components and an HTTP kit with WebSockets on the server-side and ClojureScript Om on the client-side.
  • Experimented with Raspberry Pi and PinoIR for a local bus company concept: a school bus that parents can oversee. It included an onboard computer, a WiFi router, access gates, cameras, and streaming to the server which distributed it to mobile apps.
  • Developed a travel feed aggregation app in Clojure that processed over 25,000 hotels per night with duplicate identification across streams and the ETL from SOAP services. The build process was with Boot and the front end in ClojureScript.
  • Managed a Clojure team and transitioned them to Haskell. From Clojure and JVM basics to decoupled functional architecture and pushing effects towards the border of the app.
  • Built a CQRS microservices architecture with GraphQL for reading and Haskell lambda functions for writing for a financial platform. This included investigating best approaches and prototyping event sourcing and basic services.
  • Created a custom trading algo for the Euronext stock exchange. It involved an always-on Clojure app with reboot capabilities on dropped connections, connectivity via an IBKR trading app, reconciliation, WebSockets for real-time work, a desktop app via WebKit, and a front end built in Om/Next.js.
Technologies: Computer Vision, ClojureScript, Elm, Haskell, Clojure, Erlang, Raspberry Pi, Next.js, MySQL, System Administration, Open Source, PostgreSQL, Full-stack, jQuery, Web Development, APIs, Java, React Native, TypeScript, Material UI, Git, Swagger, Node.js, Technical Architecture, Leadership, OpenAI, eCommerce, Technical Consulting, Tailwind CSS, GitHub, REST APIs, WebSockets, CI/CD Pipelines, Agile, Hibernate, Back-end

Senior Clojure Developer

2022 - 2023
Moblox Ltd
  • Installed and configured a MemoryDB cluster to support the marketing campaign using Terraform and Jedis from Clojure.
  • Handled the bug fixing in the GraphQL API and the interaction with external providers and infrastructure Terraform modifications.
  • Improved the GraphQL API from Clojure and added new mutations and queries.
Technologies: Clojure, Lisp, AWS DevOps, GraphQL, Automated Testing, Amazon Cognito, CircleCI, Terraform, DevOps

Front-end Engineer

2017 - 2018
  • Worked on multiple list filters on both the front end and back end.
  • Integrated with Salesforce data to augment customer info.
  • Utilized the Web Audio API from ClojureScript using JavaScript interop.
  • Worked on various front-end visual components on ClojureScript.
  • Handled ClojureScript async channel communication to pass along the state bottom-up.
Technologies: Elasticsearch, ClojureScript, Clojure, MySQL, System Administration, Open Source, Git

Owner | Freelance Developer

2009 - 2017
PFA Rosian Vasile Adrian "Web Solutions"
  • Developed eCommerce plugins for clients such as A1M and Euro Payment Group, major payment processors in Europe. Developed extensions for OpenCart for a multilingual food supplement website; involved mainly PHP with various frameworks and CMS types.
  • Contributed to the development of Affiliate X, a unique niche market tool for affiliate sales. The task requires working with parsing high-volume data feeds and optimizing database queries for high availability. PHP with CodeIgniter and PostgreSQL.
  • Developed data acquisition software from a Zigbee-based mesh network as part of a research paper. It involved Serial RX/TX with AT, sensor reading/calibration, PHP, Python with multi-processing, SSE for real-time work, and jQuery for the front end.
  • Managed and built a merchant acquisition platform for a large European bank that had required processing 80,000+ customers which needed integration with several external services with various degrees of automation; tech included PHP with Symfony 2.
  • Developed which involved using Clojure and ClojureScript with React wrapped in ClojureScript Om. Clients were in Swift and Java for mobile as well as Electron.js and NW.js (node-webkit) for desktop; later started a larger scale app in Erlang with Cowboy.
  • Wrote the logic for open-jaw bookings, estimations for trip costs including connected services, and the interfaces for all actors involved for a system meant to handle private jet inventory and booking. Used Yii with front-end modular components.
  • Constructed a system for radiology investigation results; used Python with Pyramid Pylons initially, then migrated to Django.
  • Contributed to the back-end part of a Java app for notification dispatches for the Romanian government as part of a volunteer team. Used Java with Spring Boot, Kafka for notifications, and CouchDB for storage.
  • Developed the Joomla components (JJAntispam, JingleSubscriptions—listed in the Joomla extensions directory) and a PHP-based internal invoicing system with PHP for a file-based blog in Go with the Martini framework.
Technologies: Rx, Octave, Machine Learning, Redux, React, Chicago Boss, Reagent, ClojureScript, Compojure, Pylons, Django, Symfony 2, Swift, Erlang, Clojure, Python, JavaScript, CSS, HTML, PHP, MySQL, System Administration, Open Source, Java, React Native, Material UI, Git, Web Scraping, APIs, Swagger, Node.js, Angular, Leadership, CodeIgniter, Technical Consulting, GitHub, REST APIs, WebSockets, Agile, Hibernate, Back-end

Web Developer

2008 - 2008
Emotion Design
  • Developed small business websites in Sibiu and the surrounding area.
  • Trained other developers in PHP, HTML, CSS, and JavaScript for the company.
  • Worked with CodeIgniter on various web applications.
  • Developed eCommerce workflows with Joomla and VirtueMart.
  • Managed a team of two junior developers and was responsible for delivery to clients.
Technologies: WordPress, Joomla, JavaScript, CSS, HTML, PHP, MySQL, System Administration, Open Source, Back-end

Kopplr Platform

A fintech startup platform for merchant onboarding and payment processing with white labeling features and cross-selling and all-around reporting. It consists of a cloud-native application living in AWS with a microservices architecture and excellent scalability.

Checkout Portal

A merchant acquisition portal for online payment solutions integrating over five systems for a German bank. The mixed solution exposes a rendered interface and a partner API with a built-in white-label system.

ITST—Private Aviation Procurement Software

An application for private jet availability and reservation, with cost estimations and multi-leg flights. I worked on the initial development prototypes after the first financing round, the patent application in the US, the business planning and market research, the team set up, and the development of the MVP.

Machine Learning Front-end for Internal Email Categorization and Search App

A machine learning front-end for internal email categorization and a search app for legal advice in a large enterprise. The front-end connected to a machine learning model that sorted emails automatically and created the pipeline for re-training the model with internal user feedback.


A travel aggregator application for a local travel agency featuring hotel searches across 25,000 hotels from five separate regional feeds, with currency matching, hotel disambiguation, and connected services.


A support chat application deployable on a customer server written in Clojure developed as a proof of concept for the support system of a German bank.
This back-end application consists of ClojureScript with a reactive front-end, a cross-platform mobile app, and plugins for popular CMSs like WordPress and Joomla. The application included invoicing system, subscription management, and software updates. I started the development of the app with Erlang. is a Python file with three functions used to:
• Detect text areas on an image using blobs of approximately the same height on a line.
• Detect the angle of rotation of the text.
• Adjust the blobs to be horizontal.

Toto—Distributed Grocery List Clojure
A hobby project with Clojure HTTP-kit WebSockets and local IndexedDB storage for experimentation on the early onsets of functional programming into the mainstream industry. The project consists of an Angular front-end with a reactive approach and WebSockets for synchronization.

Sena Probee Interface in Python
A Python multiprocessing app that exposes a Sena ProBee sensor reading from a mesh network over a web interface via server-sent events. Utilized Zigbee protocol for device communication and experimentation with displaying a live stream of light and temperature data while storing it in the database.

SplitCrypt—Encrypt by Splitting, Clojure
Contributed to implementing one of my professor's encryption algorithms for file encryption based on equivalent keys and a "zipper" type splitting of a file using the key. Clojure implementation for experimenting with the language and reducers was a very new approach at the time.

EqvKey—Compute the Equivalent Key
A method to generate stronger encryption keys by flipping the bits of a given key after a threshold number. This was part of my professor's algorithm for encryption at the local University. The Clojure software experiment was done over the weekend.

Golang MD File-based Site CMS
The engine transforms a folder structure with Markdown files into a full site using Go and the Martini web framework for excellent site speed. This project was developed long before static file CMSs were even a thing to use on my blog.

WhiteRCPT—Haskell with Servant

A receipt reading and aggregation app with a Haskell back-end and a Swift mobile app. The application exposed a Servant API for uploading receipt photos, piped them through Google Vision API, and then used custom parser-combinators to parse the resulting text into the company and receipt-related information to expose as both itemized and aggregated data to the iOS mobile app.

Notifications Dispatch in Java

A notifications dispatch for a Romanian Government initiative, written in Java. The program was volunteer-based. The hackathon MVP project was done with a team of eight, including a mobile client and presentation website. I participated in the back end using Spring Boot and CouchDB for database and topic queues.

Solvency II Wire (Toptal)

Worked on the ETL process for the platform using Python with Django and extensions. I was in charge of correct calculations using NumPy transforms and reporting the data. I also extracted data from large multi-tab Excel files.

Crypto Wallet for German Bank

A crypto wallet concept for a German bank. Contributed to the compliance checks with tracking in the blockchain, transactions using Stellar, and the ecosystem developed around it, including merchant payment plugins, the payment gateway, and blockchain integration.

Enterprise Portal Proposal for German Bank

A concept for unifying the existing three portals of a German bank and providing SSO functionality for all three applications while keeping data management and aspect/brand consistency central across different technologies.

European Multi-acquirer Portal

The concept for a European multi-acquirer portal for payments routed customers to different acquirers depending on configurable parameters from the platform. The portal would also allow redundant payment acquisition.

Payment Plugins for all OS Shopsystems

A payment plugin for the payment gateway of a Deutsche Payment A1m for all PHP-based shop systems, including the PHP SDK. I managed the maintenance and updating of the payment plugins, automated testing, and integration with the ordering system of the shops.

JJAntispam and JingleSubscriptions
Developed Joomla extensions for spam registration checks against two separate RBLs and subscription management for downloadable products. JJAntispam was a Joomla system plugin hooked at user registration with configurable actions on RBL detection. JingleSubscriptions handled recurrent payments and cancellations of subscriptions for downloadable products. Contributed to the component for administrative purposes and the content plugin for insertion of the downloads area.

VOD for a Motor Video Company

Developed the concept for a video-on-demand (VOD) service for a motor video company with distributed content delivery and signed video URLs over a custom CMS and custom Flowplayer modification. Utilized AWS S3 for storage, CloudFront distributions for edge location delivery, and Python for the back-end.

Factoring Service for Merchants

For a European bank, I developed the concept for an application that would allow merchants to get paid against their invoices through a third-party factoring service and for the integration and payment flows of the app.

Subscription Integration for a Big Digital Customer

For a German bank, we developed a concept for automating purchases of subscriptions for a sizeable digital customer. The bank's internal systems used a convoluted account setup process that needed ironing out into a solid automated process.

Partner Portal for a Large European Bank

For a German-based bank, we developed the concept for a partner portal that included onboarding and account management, contracting and reporting for marketplace and referral payments that respected the bank's branding guidelines and united several disparate technologies.

Prepaid Card Concept

For a large European bank based in Germany, we architected the software suite for a prepaid card, starting from web and mobile onboarding to expense reporting and categorization and prepaid card benefits.


An automated school bus concept for the local administration with a parent-children monitoring app, in-trip video feeds from the bus for the parents, teacher pick-up for the children, and automated ticket validation tracking for the transportation company.

St.George's Language School Booking System
A complex booking system for the school's language classes, including accommodation for the stay. I worked with the legacy codebase, migration from jQuery to Angular, Drupal back-end, and MySQL, and the credit card payments for the booking.

Biokraft Shop

A shop system for Biokraft, a Romanian wellness provider. The shop system consisted of complete orders, automated products import, invoicing, payments, shipping, multilingual process, currency conversion, taxation, and social integration.

BPM Automation Software Concept for Automotive Client

The client was a seat cover provider for large brands in Europe. According to Six Sigma indicators, it needed to be ITIL-based software for quality monitoring and management of incidents. The proposed solution consisted of a functional programming back-end and a NoSQL database.

Insurance Configuration and Payment for German Insurer

A configuration and payment platform for a German insurance company and a customer portal featuring product management, support, and contract management. The software concept, technology overview, and development plan are based on UI flows.

Construction Configurator for Real Estate Developer

A German real-estate developer building customized smart homes in a real-estate project asked for a software concept for an individual building configurator for a smart house, with plans, equipment choice, construction stage monitoring, and customer support.

Conference Voice and Text Chatbot Widget Concept

A large conference website needed a chatbot widget for their website, accessible from both the web and as a web voice request. The chatbot would provide details about the conference, schedule, venue, and tickets.

Privacy Aware Email Using Blockchain

The concept of a Dapp allows decentralized, secure email exchanges with identity and encryption ensured by Ethereum smart contracts between private participants in the scheme. Clients for all major email clients, including Outlook, Thunderbird, and Gmail extension for iOS and Android apps and the MetaMask-based browser app.

Elderly Assistance Concept App

The goal of the project was to create an infrastructure for elderly people to easily keep in touch with their loved ones via chat, and video calls, enable file transfers, and integrate payments. Created the project to have Home Station iPad apps, mobile for iOS and Android, and web access.

Game Economic App Rewrite Concept

I contributed to a project aimed to move a game economics design application from Adobe AIR to the web while keeping the interactions to allow for future monetization and user onboarding integrations.
2019 - 2023

PhD in Computer Science

Babes Bolyai University - Cluj-Napoca, Romania

2013 - 2015

Master's Degree in Computer Science

"1 Decembrie 1918" University - 3-5, Revolutiei, Sibiu, Romania

2009 - 2012

Bachelor's Degree in Computer Science

"1 Decembrie 1918" University - 5, Gabriel Bethlen, Alba Iulia

2004 - 2008

Bachelor's Degree in Military Science and Information and Organization Management

Land Forces Academy "Nicolae Balcescu" - 3-5, Revolutiei, Sibiu, Romania


Machine Learning




ExpertRating Global Certifications


Compojure, React, jQuery, REST APIs, iOS Extensions, iOS API, Vue, Node.js, OpenCV, NW.js, NumPy, Web3.js, Nethereum, Chartist.js


Git, Reagent, GitLab CI/CD, GitHub, CircleCI, Vim Text Editor, Amazon Cognito, Amazon CloudFront CDN, Amazon Simple Notification Service (Amazon SNS), Amazon Simple Email Service (SES), Terraform, Flowplayer, WebView, Growl, PrestaShop, Azure Machine Learning, Amazon Lex, MetaMask, MxGraph,


Symfony 2, ClojureScript, Django, Flask, Phoenix, Laravel, Spring Boot, Material UI, Swagger, CodeIgniter, Chicago Boss, Redux, Rx, Angular, Pylons, Next.js, React Native, Tailwind CSS, Hibernate, GWT, Qt, Spring, TYPO3, TYPO3 Flow, VirtueMart, Truffle, Electron, .NET


PHP, HTML, CSS, JavaScript, Elm, Python, Clojure, Elixir, Java, CSS2, Erlang, Octave, Swift, Haskell, TypeScript 3, GraphQL, TypeScript, Lisp, Go, Solidity, QML, C++, C#


REST, Object-oriented Programming (OOP), Microservices, DevOps, Agile, Functional Programming, Automated Testing, Azure DevOps, ITIL, Six Sigma, CQRS, Parallel Programming


WordPress, Joomla, iOS, Mobile, Fedora, Docker, Amazon Web Services (AWS), AWS Lambda, Android, Desktop, Raspberry Pi, Linux, Drupal, OpenCart, Magento, Azure, Ethereum, Blockchain


Realm, MySQL, Elasticsearch, Redis, PostgreSQL, Amazon S3 (AWS S3), MongoDB, CouchDB


Amazon API Gateway, System Administration, Open Source, Full-stack, Web Development, APIs, Web Scraping, Technical Architecture, Leadership, Technical Consulting, CI/CD Pipelines, Back-end, Research, Graphical User Interface (GUI), Software Architecture, Single Sign-on (SSO), White Labeling, Startups, Software Development, Business Planning, Remote Team Leadership, IT Project Management, Content Management Systems (CMS), Payment APIs, Subscriptions, Parsers, Servant, Software Engineering, iOS Cryptographic Services, iOS Camera, Computer Vision, Amazon Neptune, Apollo, Linear Regression, Polynomial Regression, Support Vector Machines (SVM), Clustering, eCommerce, WebSockets, Category Theory, AWS DevOps, Cloudflare, Financing, Incident Management, Quality Control (QC), Encryption, Martini, App Store, BrainTree, Invoice Management, Operating Systems, Compilers, Machine Learning, Neural Networks, OpenAI, Legal, Amadeus, Market Research, US Patent Process, Zigbee, Google Play Store, Cowboy Server, Logistic Regression, Onboarding, Invoicing, Process Automation, Internet of Things (IoT), Wireless Systems, IT Systems Architecture, Networking, Video Streaming, Shopware, SOAP, BPM, Amazon RDS, ÐApp

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