Mike Szyndel, Developer in Berlin, Germany
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Mike Szyndel

Verified Expert  in Engineering

Software Developer

Berlin, Germany
Toptal Member Since
June 28, 2017

Mike is a seasoned full-stack developer and software architect with in-depth knowledge of Node.js, Ruby on Rails, and React. He has a unique ability of understanding and translating business requirements into development roadmaps. In his previous roles as a team lead and CTO, he has developed strong project management and communication skills.


Ruby, Ruby on Rails (RoR), Apache Kafka, React, MySQL, Scaling, Performance...
Fortune 500 Manufacturing Company
Ruby, CSS, REST APIs, Back-end Development, PostgreSQL, JavaScript...
Prodigy Finance
React, Ruby, CSS, REST APIs, Back-end Development, PostgreSQL, JavaScript...




Preferred Environment

Atom, MacOS

The most amazing...

...thing I've built was a distributed scraper which continuously indexed all YouTube channels.

Work Experience

Senior Software Developer

2021 - 2022
  • Scaled a centralized package tracking system to process 160 million shipments and 2+ billion status updates per month.
  • Collaborated with external partners, such as UPS, DHL, and Parcel Perform, designing and building state-of-the-art integrations. This work led to much higher throughput, lower latencies, and cost savings of $500,000 per year.
  • Mentored junior engineers through pair programming and code reviews, involving them in higher-level technical design work and department-wide show and tells. Helped build promotion case from an intern to the developer, skipping the junior level.
Technologies: Ruby, Ruby on Rails (RoR), Apache Kafka, React, MySQL, Scaling, Performance, Cargo & Shipping, Technical Design, Technical Leadership, Hiring, Interviewing, GraphQL, Software Architecture, eCommerce, Shopify, Technical Architecture, Leadership, Full-stack, Project Management, GitHub, Web Scraping, Python, HTML, API Integration, RSpec, ActiveAdmin, REST

Senior Software Engineer

2019 - 2020
Fortune 500 Manufacturing Company
  • Created a library of reusable React components, including documented use cases in Storybooks and tests in Jest/Enzyme.
  • Implemented ARIA landmark 1 accessibility requirements.
  • Upgraded an existing data API service from Rails 4 to Rails 6.
  • Implemented new data API endpoints, focusing on speed, caching, and data structure tailored for the presentation layer.
  • Migrated legacy local websites into a single multilingual site.
  • Lowered the cost of feature development, improved delivery times, largely removed QA issues on new pages, and improved site performance.
Technologies: Ruby, CSS, REST APIs, Back-end Development, PostgreSQL, JavaScript, Amazon Web Services (AWS), Dynamics CRM 365, Docker, Enzyme, Jest, Storybook, Ruby on Rails (RoR), React, Web Development, Software Architecture, Jira, Architecture, APIs, Technical Leadership, Technical Architecture, Leadership, Full-stack, Project Management, GitHub, HTML, API Integration, RSpec, ActiveAdmin, REST

Senior Software Engineer

2018 - 2019
Prodigy Finance
  • Prepared architectural outline and led implementation of an OAuth OpenID Connect provider, enabling single-sign-on (SSO) to all Prodigy services.
  • Migrated existing services from EC2 to ECS Fargate, enabling autoscaling, blue-green deploys, and improving security.
  • Reimplemented existing Excel cash flow models as a Ruby on Rails and React application, lowering turnaround time for new models from days to minutes.
Technologies: React, Ruby, CSS, REST APIs, Back-end Development, PostgreSQL, JavaScript, Financial Data, OpenID Connect (OIDC), Amazon Web Services (AWS), Python, OpenAPI, OAuth, Docker, Ruby on Rails (RoR), Web Development, Software Architecture, Architecture, APIs, Slack, Asana, Team Leadership, Technical Leadership, Technical Architecture, Leadership, Full-stack, Project Management, GitHub, HTML, API Integration, RSpec, REST

Project Leader

2018 - 2018
Market Research Company
  • Gathered business requirements and provided timeline and technical architecture of the project.
  • Built a distributed, queue-based, horizontally scaling scraper in Node.js, deployed to ECS.
  • Integrated residential IP address proxy and CAPTCHA solving service.
  • Implemented the ETL process, ingesting data from Alibaba, AliExpress, Taobao, and Tmall.
  • Built the React front end, allowing data filtering, data export, and scraping progress monitoring.
Technologies: CSS, REST APIs, Back-end Development, PostgreSQL, JavaScript, Amazon Web Services (AWS), Amazon Elastic Container Service (Amazon ECS), Project Management, Web Scraping, React, Express.js, Node.js, ETL, Web Development, Software Architecture, Architecture, APIs, Team Leadership, Technical Leadership, Leadership, Full-stack, Bitbucket, HTML, API Integration, Heroku, RSpec, REST, AliExpress


2014 - 2017
  • Developed a tool indexing more than 30 million unique YouTube channels weekly, using a mix of API access and scraping.
  • Rebuilt a legacy jQuery front end in React from scratch for both Stagelink customer-facing products; moved away from a monolithic Rails app towards API-based services.
  • Implemented and optimized a show-attendance prediction algorithm designed by the company's CEO. Deployed the new code to production—increasing prediction accuracy by 15% and increasing the calculation speed three-fold.
  • Hired and led a team of six developers—performing code reviews and training sessions, having one-on-one meetings every two weeks, and mentoring junior developers.
  • Designed a voting fraud detection system that analyzed tens of thousands of votes per day to identify fake users, multiple votes by the same person, and other abuses.
  • Implemented an extensible payment back end, interfacing with multiple payment providers, including PAYMILL, Stripe, PayPal, SOFORT, and Wirecard.
Technologies: CTO, Facebook Open Graph API, CSS, REST APIs, Back-end Development, Pipedrive API, Web Scraping, Amazon Web Services (AWS), PostgreSQL, Elasticsearch, Redux, React, JavaScript, Ruby on Rails (RoR), Ruby, Web Development, Software Architecture, Architecture, APIs, Slack, Asana, Team Leadership, Technical Leadership, SendGrid, SendGrid API, Technical Architecture, React Native, Leadership, Full-stack, Project Management, Bitbucket, HTML, API Integration, BrainTree, Heroku, RSpec, ActiveAdmin, Payment APIs, REST

Software Engineer

2012 - 2013
Digital Polsat
  • Developed a search engine for a music-streaming platform consisting of more than 15 million songs. The search engine was based on Elasticsearch and MongoDB and was deployed to a cluster of EC2 servers.
  • Finetuned a search engine configuration based on artist popularity and measurements of hit/miss ratio for presented results.
  • Exposed the search engine to mobile, web, and desktop applications by building a JSON-based API service in Rails.
  • Implemented a recommendation service based on user preferences, content team picks, etc.
  • Developed a caching-layer based on Memcached (for in-app caching) and Varnish (for page and endpoint-level caching).
Technologies: Facebook Open Graph API, CSS, Back-end Development, PostgreSQL, JavaScript, Amazon Web Services (AWS), Elasticsearch, MongoDB, Ruby on Rails (RoR), Ruby, Web Development, APIs, Full-stack, HTML, API Integration, Heroku, REST

Full-stack Developer

2010 - 2011
  • Integrated LiveChat with various third-party applications including Zendesk, Salesforce, Highrise, and Zoho to pull customer data into a chat window.
  • Built an outside-facing REST API, wrote docs and sample code, helped outside developers integrate with it, and troubleshot issues.
  • Created chat plugins for popular eCommerce solutions (Shopify, Magento, WooCommerce, and the like).
  • Developed a wizard allowing LiveChat clients to customize their chat experiences for their users by changing the color scheme for the chat window, adding pre-chat questions, and a post-chat survey.
  • Built an API for an internal dashboard showing sales and usage statistics.
Technologies: CSS, REST APIs, Back-end Development, JavaScript, RESTful Development, MySQL, jQuery, PHP, Web Development, APIs, Full-stack, HTML, API Integration, REST

Software Developer

2009 - 2010
  • Designed and implemented a quality assurance application—including a dynamic survey generator and HTML5 audio player. I also developed a back-end service that selected a random sample from a pool of all sales calls recorded on a previous day.
  • Wrote, specified, designed, and developed an applicant-tracking system according to HR department requirements.
  • Migrated the internal apps from a legacy homegrown PHP framework to Symfony.
Technologies: CSS, Back-end Development, MySQL, jQuery, JavaScript, PHP, Web Development, APIs, Full-stack, HTML, REST

Stack Overflow

With over 250 answers and more than 8,600 points, I'm in the top 5% of Stack Overflow users overall.


Being the CTO, I was responsible for all sorts of things at Stagelink. In the day-to-day work, I was coding and managing a team, occasionally jumping into server and AWS administration, developing product roadmaps and writing specifications, performing code reviews and one-on-ones with developers, negotiating with designers, and so on.

The things that I'm most proud of:
• We went through two major redesigns of the website while improving usability, performance, the looks, and user satisfaction.
• I successfully moved away from the monolithic Rails app towards an API—cleanly separating the front-end from back-end with some background services performing the heavy lifting (like emails, and so on).
• I made the right technical decisions by separating different parts of the product codebase and making them communicate via an API. This saved us from many headaches when scaling-up.
• I helped new developers quickly get proficient with Stagelink's code and systems—to decrease the bus factor.

Pipedrive Gem

Pipedrive is a type of CRM software, and we used it a lot at Stagelink to track our sales efforts. Based on the YouTube scraping results, we were sending cold emails to matching artists and tracked the progress in Pipedrive.

We started to use a gem to make our lives easier, but the code was pretty terrible. In my free time, I started refactoring it and bringing the quality (and code coverage) up a bit—we are planning to release a new version at some point.

Work Done:
• Removed recursion from the paging-handling code.
• Moved the HTTP calls out of the data objects.
• Performed general cleanup of the code.
• Updated the dependencies and made it work with the current Ruby versions.
2006 - 2011

Master of Science Degree in Computer Science

Wrocław University of Science and Technology - Wrocław, Poland


Stripe, ActiveRecord, REST APIs, Sidekiq, Stripe API, Stripe Connect, Node.js, Twilio API, jQuery, PayPal API, React, Facebook Open Graph API, Facebook API, YouTube API, TensorFlow, Slack API, Amazon EC2 API, SendGrid API, OpenAPI, Pipedrive API


Slack, Git, Amazon CloudFront CDN, Jira, GitHub, RSpec, SOFORT, Wirecard, PAYMILL, Asana, G Suite, Trello, Bitbucket, Confluence, Docker Compose, Amazon EBS, Redux Thunk, SendGrid, Atom, Amazon Elastic Container Service (Amazon ECS)


Express.js, Redux, Bootstrap, Ruby on Rails 5, minitest, Ruby on Rails (RoR), Ember.js, Jest, React Native


SQL, CSS3, Sass, Haml, HTML5, CSS, HTML, ECMAScript (ES6), ES5, JavaScript, Ruby, PHP, Python, GraphQL


RESTful Development, MVC Design, REST, Continuous Delivery (CD), Management, Back-end Architecture, Agile Software Development, Test-driven Development (TDD), Continuous Integration (CI), Requirements Analysis, Scrum, Agile, HIPAA Compliance, ETL


Heroku, MacOS, Linux, Amazon EC2, Amazon Web Services (AWS), Docker, Twilio, Shopify, AWS Lambda, Apache Kafka, AliExpress


ANSI SQL, Database Administration (DBA), Memcached, PostgreSQL, Amazon S3 (AWS S3), MySQL, MongoDB, Redis, Elasticsearch

Industry Expertise

Project Management, Cybersecurity


Architecture, IT Project Management, API Integration, Web Scraping, BrainTree, Full-stack, Infrastructure, Payment Gateways, Quality Assurance (QA), QA Leadership, QA Automation, Software QA, Software Architecture, APIs, CSV File Processing, Web Development, Mobile Back-end, Back-end Development, Back-end Performance, Back-end, RESTful Services, RESTful Web Services, Ruby Gems, High Code Quality, CTO, Business Requirements, Technical Leadership, ActiveAdmin, IT Consulting, System Integration, Consulting, Solution Architecture, Data Modeling, Requirements & Specifications, Stripe Payments, Leadership, Team Leadership, eCommerce, Technical Architecture, Lambda Functions, Payment APIs, OAuth, Financial Data, Technical Design, OpenID Connect (OIDC), Storybook, Enzyme, Dynamics CRM 365, CRM APIs, Serverless, Scaling, Performance, Cargo & Shipping, Hiring, Interviewing

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