Clemens Helm, Developer in Vienna, Austria
Clemens is available for hire
Hire Clemens

Clemens Helm

Verified Expert  in Engineering

Software Developer

Vienna, Austria
Toptal Member Since
October 24, 2017

Clemens has been working as a full-stack web developer for over a decade and a half. He's passionate about designing and building high-quality products. What he loves most about freelancing is the opportunity to encounter various types of projects, people, and cultures. Working this way, he constantly gains experience and knowledge for his next projects.


React, Ruby on Rails (RoR), GraphQL, PostgreSQL, Tailwind CSS, Ruby
Clemens Helm
Sass, jQuery, React, JavaScript, Meteor, Ruby on Rails (RoR), Ruby
Ruby on Rails (RoR), React, GraphQL, RabbitMQ, PostgreSQL, MongoDB, Apache Solr




Preferred Environment

Git, Zsh, ITerm, Vim Text Editor, Atom, MacOS

The most amazing...

...platform I've built is Codeship, a continuous integration service for developers.

Work Experience

Senior Full-Stack Developer

2021 - PRESENT
  • Improved an eCommerce platform for sending and receiving gifts with Ruby on Rails and React.
  • Implemented interfaces to third-party eCommerce providers.
  • Created solid and fast-performing user interfaces with React and Tailwind CSS.
  • Implemented advanced search functionality using triggers and search vectors with PostgreSQL.
Technologies: React, Ruby on Rails (RoR), GraphQL, PostgreSQL, Tailwind CSS, Ruby

Freelance Web Application Developer

2006 - PRESENT
Clemens Helm
  • Developed solid corporate websites with PHP, JavaScript, and CSS.
  • Helped early-stage startups with their software architecture by developing an MVP and mentoring junior developers.
  • Created features for legacy Ruby on Rails codebases and cleaned them up by introducing test-driven development followed by an extensive refactoring.
  • Implemented data imports from Twitter, Instagram, and other APIs.
  • Processed images with ImageMagick to enhance certain aspects like their dominant color—in a way like Instagram filters.
Technologies: Sass, jQuery, React, JavaScript, Meteor, Ruby on Rails (RoR), Ruby


2019 - 2021
  • Managed a small team of web, iOS, and Android developers.
  • Transitioned the outdated front end to a modern stack using Webpack, TypeScript, and React.
  • Improved the overall architecture while simultaneously reducing overall complexity and improving reliability.
  • Created a GraphQL API on top of Ruby on Rails to give front-end developers the flexibility to fetch exactly the data they need.
  • Made sure everyone on the team was happy and productive.
  • Did a ton of other stuff, like planning sprints, reviewing pull requests, communication with stakeholders, etc.
Technologies: Ruby on Rails (RoR), React, GraphQL, RabbitMQ, PostgreSQL, MongoDB, Apache Solr

Lead Full-stack Developer

2018 - 2020
  • Developed a mobile app for a community of people using a certain medical product.
  • Led a small team of web developers working with Vue.js and Ruby on Rails.
  • Coordinated communication with several stakeholders within Temedica as well as from external clients.
Technologies: Ruby on Rails (RoR), Vue, Vuex, React Native, PostgreSQL, Redis, Amazon Web Services (AWS)

Senior Front-end Developer

2019 - 2019
  • Improved the PSPDFKit web viewer, a toolkit to render and annotate PDF documents in the browser.
  • Developed examples of usage scenarios for the PSPDFKit web viewer to demonstrate use cases.
  • Wrote guides to showcase features of the web viewer.
Technologies: React, Webpack, Elixir, Middleman

Senior Full-stack Developer

2018 - 2019
  • Got introduced to developing smart contracts on a blockchain.
  • Developed an electron application that manages sandboxed Node.js processes.
  • Collaborated with an international team of developers.
Technologies: React, Electron, MobX, Node.js, Storybook, Docker


2015 - 2018
  • Created a web platform for automated accounting using Meteor, MongoDB, and React.
  • Developed a robust invoice recognition software using Ruby, ImageMagick, and Tesseract.
  • Led a team of nine brilliant web developers and data scientists.
  • Created a strong product vision and planned the product features according to the vision and customer feedback.
  • Used several APIs for reliable currency conversion, safe vat number validation, and others.
Technologies: React, Ruby, Meteor

IT Consultant | Mentor

2015 - 2016
  • Advised a team of founders about technology stacks and product strategies.
  • Mentored junior developer on how to develop a solid Ruby on Rails app.
  • Implemented critical features which required a senior developer.
  • Reviewed code to ensure code quality and performance.
  • Provided my product team with feedback on their roadmap.
Technologies: PostgreSQL, Ruby on Rails (RoR), Ruby

Full-stack Developer

2014 - 2015
  • Created a reliable business workflow web application for real-estate companies.
  • Refactored the existing code to make it as maintainable as possible.
  • Gained a lot of experience with MongoDB indexing and deployment on a database of a few terabytes.
  • Worked on a huge Ruby on Rails app with hundreds of thousands of lines of code.
  • Developed a sophisticated full-text search with Elasticsearch and gained experience in deploying it.
Technologies: Redis, MongoDB, Ruby on Rails (RoR), Ruby

Vice President of Engineering

2012 - 2014
  • Developed a hosted continuous integration platform using Ruby on Rails, PostgreSQL, and LXC.
  • Led a team of several brilliant software developers.
  • Participated in the TechStars Boston program with the Codeship team.
  • Managed and developed the front and back end of the entire Codeship web application.
  • Developed an exhaustive testing suite to ensure the reliability and expandability of the platform.
Technologies: Sass, Redis, PostgreSQL, Ruby on Rails (RoR), Ruby

Codeship is a continuous integration platform in the cloud. I was involved in developing the entire web application as well as the continuous integration service. I developed a highly scalable application which is used by thousands of software development teams every day.


An automated accounting tool for small businesses. As the CEO and CTO, I was involved in the technical and production aspects as well the business side. Through this, I learned to view software applications from different angles.

Medbee provides a platform for medical professionals to share knowledge with each other.
I led the tech team as CTO and coordinated development on a wide range of technologies, like Ruby on Rails, React, GraphQL, and Android and iOS native development. I also actively developed in the web front end and back end.
2008 - 2017

Master's Degree (in Progress) in Software Engineering and Internet Computing

The Vienna University of Technology | TU Wien - Vienna, Austria

2008 - 2017

Master's Degree (in Progress) in Media and Computer Science

The Vienna University of Technology | TU Wien - Vienna, Austria

2009 - 2009

Master's Degree (Spent a Semester Abroad) in Computer Engineering

Faculdade de Engenharia da Universidade do Porto - Porto, Portugal

2003 - 2008

Bachelor's Degree in Media and Computer Science

The Vienna University of Technology | TU Wien - Vienna, Austria


React, Node.js, jQuery, MobX, Vue, Vuex, Mongoid, Marionette.js, ImageMagick


Cucumber, Codeship, Amazon Elastic Container Service (Amazon ECS), Git, Atom, Vim Text Editor, Webpack, Middleman, RabbitMQ, Apache Solr, Solr, Zsh, Amazon Elastic Container Registry (ECR), AWS SDK, ITerm


JavaScript, Ruby, HTML, SQL, CSS, Sass, HTML5, TypeScript, Elixir, GraphQL, Swift


Test-driven Development (TDD), Behavior-driven Development (BDD), Object-oriented Programming (OOP), Unit Testing, Testing, Software Testing, Continuous Delivery (CD), Continuous Development (CD), Agile, Functional Programming, Continuous Integration (CI), Scrum


Meteor, Heroku, Amazon Web Services (AWS), MacOS, Amazon EC2, Docker


Amazon S3 (AWS S3), Redis, MongoDB, PostgreSQL, Databases, Memcached, JSON


Electron, Ruby on Rails (RoR), Material UI, Express.js, React Native, Tailwind CSS


Semantic UI, Full-stack, Web Development, APIs, Product Management, Tesseract, Usability, Storybook, Software Engineering, Computer Science, Computer Engineering, Image Processing, Lean Product Development, Product Development

Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.


Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring