Hendrik Wermser
Verified Expert in Engineering
Ruby on Rails Developer
Brunswick, Lower Saxony, Germany
Toptal member since February 22, 2022
For 7+ years, Hendrik was the main Ruby on Rails engineer in two different startups, in charge of all technology, including the front and back ends, databases, CI/CD, cloud deployment, error and performance monitoring, logging, analytics, and A/B testing. In the past two years, Hendrik has been a remote freelance team member for a SaaS startup, developing a proof-of-concept of a Flask, Python, and Vue.js application for use in hospitals. He has also taught a coding boot camp for two years.
Portfolio
Experience
- JavaScript - 10 years
- SQL - 10 years
- Ruby - 7 years
- CI/CD Pipelines - 7 years
- Heroku - 7 years
- Ruby on Rails (RoR) - 7 years
- Computer Science - 5 years
Work Experience
Ruby on Rails Core Engineer
FlashParking, Inc.
- Joined a large Ruby on Rails codebase with container-based deployment, CI pipelines, and SQL and NoSQL databases.
- Developed complex interactions with third-party APIs.
- Monitored production deployments for performance issues and reported and fixed multiple related issues.
Lead Teacher, Web Development
Ironhack (Part-time)
- Taught web development principles, tools, and best practices to aspiring web developers with the help of two teaching assistants.
- Debugged students' projects and deployed each of them on Netlify and/or Heroku.
- Kept teaching materials up to date and continuously improved their comprehensibility.
Principal Full-stack Developer
Avocando
- Developed a technology platform for shoppable content and smart home integrations as the principal engineer on the team. The application made recipe content shoppable at different online grocery shops. Avocando became part of Samsung Whisk in 2018.
- Developed and maintained JavaScript snippets and widgets for integration with many third-party web applications and websites.
- Set up and maintained all API integrations and ETL/data pipelines.
Senior Full-stack Developer
Simplora
- Developed a price comparison application for grocery shopping as the main engineer on the team. Used linear optimization to compare prices across entire shopping carts, not just individual products. It had a RoR back end and JavaScript SPA front end.
- Set up and optimized multiple Elasticsearch instances with language-specific customization.
- Oversaw the entire deployment, performance and error monitoring, and continuous maintenance of the application.
Junior Web Developer
i-sense Software GmbH
- Developed customizations of the company's SaaS solution for different customers using mainly jQuery, PHP, and MySQL.
- Developed and maintained custom XML helper libraries to help scale the customization process.
- Monitored customers' installations and provided support and ad-hoc solutions during incidents.
Project History
SaaS Prototype for Hospitals
Linear Optimization Library for Grocery Shopping
JavaScript Cross-origin Communication Library
Simple Metadata Web Crawler Using Mitmproxy
Education
Master's Degree in Computer Science
Technical University Munich - Munich, Germany
Bachelor's Degree in Computer Science
Technical University Munich - Munich, Germany
Skills
Libraries/APIs
Node.js, REST APIs, React, Backbone.js, Sidekiq, Vue, Puppeteer, Mechanize, Nokogiri, MooTools, jQuery
Tools
RubyMine, Slack, Git, Docker Compose, Postman, Google Analytics, Vagrant, Ansible, Sentry, Fastly, Varnish, Travis CI, Honeybadger.io, GitHub, RSpec, BrowserStack, Optimizely, Let's Encrypt, Webpack, Cucumber, Pivotal Tracker
Languages
Ruby, JavaScript, SQL, CSS, HTML, Python, PHP, XML, XPath, XQuery
Frameworks
Ruby on Rails (RoR), Ruby on Rails 5, Bootstrap, Selenium, Flask, Capybara, Express.js
Platforms
MacOS, Heroku, Docker, Amazon Web Services (AWS), New Relic, Google Cloud Platform (GCP), Netlify
Storage
PostgreSQL, Elasticsearch, MongoDB, MySQL, NoSQL, Amazon S3 (AWS S3), Redis, Data Pipelines
Paradigms
ETL, Linear Programming, CSRF Protection, Agile, Kanban
Other
APIs, CI/CD Pipelines, Computer Science, WebSockets, Web Security, Web App Security, APM, 3D, A/B Testing, Ruby Gems, CORS, Third-party Integration, Proxy Servers
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