Davorin is available for hire
Hire DavorinDavorin Šego
Verified Expert in Engineering
CSS Developer
Split, Croatia
Toptal member since November 9, 2015
Bio
Full-stack engineer with nearly 20 years of experience building web applications, most recently a fintech platform that handles sensitive tax and financial data. Works across the stack in React/TypeScript, PHP/Laravel, and Python/Django, from data models and APIs to the finished UI. Long background in data-heavy products: dashboards, interactive maps, charting tools, surveys, and booking systems. Writes testable, maintainable code and has worked remotely with distributed teams for over a decade.
Portfolio
Harness Wealth Advisers
React, TypeScript, Laravel, Inertia, Django, PostgreSQL, HTML5, SQL, CSS...
Lam Research (via Toptal)
JavaScript, Node.js, Swagger, React, PostgreSQL, Docker, Git, D3.js, Plotly...
SHIFT (via Toptal)
Bootstrap, TypeScript, CoffeeScript, MobX, React, Mithril.js, MySQL, Laravel...
Experience
- HTML - 15 years
- CSS - 15 years
- HTML5 - 10 years
- SQL - 10 years
- PHP - 10 years
- JavaScript - 10 years
- React - 8 years
- TypeScript - 6 years
Work Experience
Senior Full-stack Developer
2020 - PRESENT
Harness Wealth Advisers
- Was the main contributor to the multi-section questionnaire across front end and back end, including conditional logic, repeating groups, auto-save, progress tracking, year-over-year prefill for returning clients, and Excel/CSV export for advisors.
- Worked on the document system, from storage to UI. That covers GCS storage with signed URLs and malware scanning, LLM-based auto-categorization, drag-and-drop upload, in-browser PDF preview, and team-based access control.
- Helped design and build the notification and reminder system, with consolidated task emails, configurable cadence, calendar-based triggers, and multi-contact delivery, which reduced manual follow-up by advisors.
- Built most of the 2FA across the full stack, including TOTP setup with QR codes, backup codes, and trusted devices, replacing a legacy SMS-based system.
- Worked on the engagement workflow engine that runs the tax service lifecycle, including tasks for e-sign, e-file, questionnaire, upload, and payment.
- Worked on the integration layer between the Laravel advisor platform and the Django client back end, and on a custom Laravel mail transport that sends email through HubSpot.
- Integrated Mixpanel, HubSpot tracking, and Sentry across user flows, and managed feature flags through rollout and removal.
Technologies: React, TypeScript, Laravel, Inertia, Django, PostgreSQL, HTML5, SQL, CSS, Lodash, HTML
Dashboard Engineer
2020 - 2021
Lam Research (via Toptal)
- Designed and built REST API endpoints to feed the dashboards using Node.js and Swagger.
- Created powerful web-based visualizations based on the Power BI files provided, using the Plotly graphing library and Pandas for data analysis.
- Laid the groundwork for a new React front end and helped re-implement a portion of the existing codebase into React.
- Improved an interactive map tool built with SVG.js to support loading external data. Implemented new features based on the provided designs.
- Participated in technical discussions with the engineering team and helped plan the new architecture and project structure.
Technologies: JavaScript, Node.js, Swagger, React, PostgreSQL, Docker, Git, D3.js, Plotly, Pandas, Python, Flask, REST APIs, SVG.js, Express.js, Microsoft Power BI, Mithril.js, Storybook, YouTrack, HTML5, SQL, CSS, HTML
Full-stack Developer
2018 - 2019
SHIFT (via Toptal)
- Wrote understandable, testable code with an eye toward maintainability.
- Developed full-stack features, including psychometric tests, surveys, dashboards, reports, and data visualizations.
- Participated in technical architecture discussions and helped drive technical decisions.
- Solved technical problems in collaboration with other engineers on the team.
- Performed code reviews in conjunction with the other developers.
- Developed new front-end product features with a focus on creating a seamless user experience.
- Integrated web analytics and customer experience platforms into the product.
Technologies: Bootstrap, TypeScript, CoffeeScript, MobX, React, Mithril.js, MySQL, Laravel, HTML5, SQL, CSS, Lodash, HTML
Web Developer
2016 - 2017
2nd Nature, LLC (via Toptal)
- Helped develop feature-rich map tools built on top of Leaflet, a JavaScript library for interactive maps.
- Created a CSV import of map features with data validation, preview, and the ability to remap fields.
- Developed auditing back-end code to keep track of user actions.
- Created basic end-to-end tests with the Nightwatch browser automation framework.
- Implemented single sign-on access control, based on web tokens, for a suite of online tools.
- Rewrote and refactored existing PHP back-end code with the Lumen framework.
- Fixed bugs and cleaned up code in the existing codebase.
- Implemented export functionality for PostGIS map features, with support for shapefiles and XLS format.
Technologies: Git, Nightwatch.js, Baobab, Nunjucks, Leaflet, Lumen, PostGIS, GeoJSON, JavaScript, jQuery, PHP, HTML5, SQL, CSS, HTML
Full-stack Developer
2015 - 2017
Pareto Solutions (via Toptal)
- Created a multi-step checkout page with the Stripe API.
- Created a CSV tool to update database rows in bulk with preview functionality.
- Implemented required functionalities for a web app that uses the Facebook API for reporting, analytics, and marketing automation.
- Worked on numerous CakePHP projects and created interactive demos with HTML5 and JavaScript.
- Created a prototype web tool for automating bids with Facebook's advertising platform.
- Created an editing tool prototype based on React Data Grid that saves data to Firebase.
Technologies: Firebase, Redux, React, Node.js, Stripe API, Facebook API, MongoDB, MySQL, Sass, jQuery, Git, CakePHP, HTML5, SQL, CSS, HTML
Senior Web Developer
2013 - 2015
Extension Engine
- Implemented new features on PaintNite, a website for organizing painting parties.
- Created a web tool for uploading and managing files with endless scrolling and quick file preview.
- Implemented Backbone.js UIs for search and course discovery on Open edX, an online learning platform.
- Worked on a proprietary social learning platform that integrates Open edX via a RESTful API.
- Contributed features and bug fixes to Open edX, an online learning platform.
- Implemented unit, integration, and acceptance tests for Python and JavaScript code.
Technologies: Jasmine, Vagrant, Sass, ZURB Foundation, Backbone.js, Django, Python, jQuery, CakePHP, HTML5, SQL, CSS, HTML
Web Developer
2012 - 2013
ImadeThis AS
- Implemented a publication reader for mobile devices using HTML5, JavaScript, and sophisticated CSS animations.
- Worked on Spreads, a digital publication platform.
- Picked up the fundamentals of the Bootstrap framework and the Less CSS preprocessor alongside PHP and CodeIgniter back-end work.
Technologies: Git, Bootstrap, Less, jQuery, CodeIgniter, CSS, HTML
Web Developer
2009 - 2012
Extension Engine
- Helped build a website for CompStudy, a web service for compensation surveys.
- Implemented a multi-step web-based questionnaire tool with PHP and JavaScript.
- Built an interactive charting tool to allow a user to chart, graph, filter, and sort data in different ways.
- Worked on Parent School Network, a school information and engagement platform.
- Created several client websites on Drupal 6 and WordPress, from setup and content structure to custom themes and templates built with PHP, MySQL, and jQuery.
Technologies: Subversion (SVN), WordPress, jQuery, Drupal 6, MySQL, PHP, SQL, CSS, HTML
Web Developer
2007 - 2009
Booking IT
- Created a solution to seamlessly integrate an e-booking web form into hotel websites.
- Supported a centralized booking system using .NET and MS SQL.
- Improved the design and usability of several PHP and .NET websites.
- Created a Joomla website for a local municipality.
Technologies: JavaScript, PHP, .NET, CSS, HTML
Co-founder and Web Developer
2006 - 2007
Kinitos
- Worked in a small team to envision and develop a real-time online booking system for yacht charters.
- Helped design a complex relational database for the booking system.
- Created elaborate .NET web forms for administering boats, equipment, and services.
- Implemented optimized SQL procedures for MS SQL Server.
Technologies: JavaScript, Microsoft SQL Server, .NET, CSS, HTML
Project History
Open edX
Front-end and full-stack development within the Solutions team at edX. Worked on a proprietary social learning platform that integrates Open edX via a RESTful API. Contributed features and bug fixes to Open edX.
Spreads - Digital Publication Platform
Spreads.no - digital publication platform. Implemented a publication reader for mobile devices using HTML5, JavaScript, and sophisticated CSS animations, delivering smooth page transitions and a responsive, touch-friendly reading experience across phones and tablets.
CompStudy
http://compstudy.orgHelped build CompStudy, a web-based compensation survey tool with a multi-step PHP and JavaScript questionnaire and interactive reports that chart, filter, and sort salary and equity data for executives at venture-backed companies.
Education
2003 - 2008
Master's Degree in Computer Science
Faculty of Electrical Engineering, Mechanical Engineering, and Naval Architecture - Split, Croatia
Skills
Libraries/APIs
React, Lodash, jQuery, Facebook API, Stripe API, Nightwatch.js, Leaflet, Backbone.js, Underscore.js, Node.js, MobX, D3.js, Pandas, REST APIs, SVG.js, Inertia
Tools
Subversion (SVN), Vagrant, Baobab, NPM, Gulp, Git, Sublime Text, Webpack, Deployer, Plotly, Microsoft Power BI, YouTrack, Claude Code
Languages
JavaScript, TypeScript, HTML5, PHP, CSS, SQL, HTML, CSS3, CoffeeScript, Less, Sass, Python, SCSS
Frameworks
CodeIgniter, .NET, CakePHP, Django, ZURB Foundation, Jasmine, Redux, Lumen, Bootstrap, Express.js, Mithril.js, Laravel, Swagger, Flask
Paradigms
Agile Software Development, Object-oriented Programming (OOP)
Platforms
MacOS, Ubuntu, Drupal 6, WordPress, Firebase, Linux, Docker, Drupal
Storage
Microsoft SQL Server, MongoDB, PostGIS, MySQL, PostgreSQL
Other
Responsive UI, GeoJSON, Nunjucks, Storybook, Ajax
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