Jarek Lipski, Developer in Paris, France
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Jarek Lipski

Verified Expert  in Engineering

Software Developer

Paris, France
Toptal Member Since
November 15, 2018

Jarek is a full-stack developer with more than 15 years of experience. He currently specializes in Vue, Node.js, and Firebase, as well as Flask, Django, and Ruby on Rails development. Throughout his career, he has worked in various industries in different roles: cloud operations specialist, back-end developer, front-end developer, team leader, and scrum master. In his spare time, Jarek is an open-source contributor and tech blogger.


Ruby on Rails (RoR), Vue, Amazon Web Services (AWS), SCSS, PostgreSQL
Vue, Nuxt.js, Vue 3, Azure, Directus, Git, GitLab, Tailwind CSS, TypeScript
Webflow, Webflow CMS, HTML, CSS, JavaScript, Segment, Alpine.js




Preferred Environment

Amazon Web Services (AWS), Firebase, Docker, Node.js, Vue, Nuxt.js, Python, Flask, JavaScript, Ruby on Rails (RoR)

The most amazing...

...project I've built is a conference companion progressive web application used by hundreds of people during FOSDEM.

Work Experience

Senior Full-stack Engineer

2022 - PRESENT
  • Added a CRM functionality to the subscription analytics platform.
  • Developed subscription cancellation management with Brightback.
  • Learned Ruby and Ruby on Rails while developing a complex application and completed several online courses (Pragmatic Studio and RubyMonk).
Technologies: Ruby on Rails (RoR), Vue, Amazon Web Services (AWS), SCSS, PostgreSQL

Front-end Developer

2022 - 2022
  • Developed multilingual terms and conditions and privacy policy pages used in multiple regions and across all products, including web, mobile, and shop.
  • Enabled the recording of the user's consent in the database.
  • Added a feature to legal documents, allowing them to be versioned and previewed before deployment.
Technologies: Vue, Nuxt.js, Vue 3, Azure, Directus, Git, GitLab, Tailwind CSS, TypeScript

Web Developer

2020 - 2022
  • Developed a brand new company website from scratch, containing custom components, like timeline, sliders, and others.
  • Built the website to include four regional variants. Synchronization is done in an optimized manner to avoid duplication while maintaining flexibility for regional teams.
  • Built the styles and symbols so that the client can manage the content autonomously via Webflow Editor without touching the code or via CMS.
  • Migrated a fully functional blog from an existing blogging platform to the website. The content is managed via CMS, like posts, categories, authors, and others.
  • Integrated website with Salesforce CRM. Added custom Typeform forms. Configured analytics and A/B testing experiments.
Technologies: Webflow, Webflow CMS, HTML, CSS, JavaScript, Segment, Alpine.js

Full-stack Developer

2019 - 2022
  • Architected and developed a complete webinar platform (landing page builder, back office, authentication, polls) used by thousands of participants per event.
  • Built interactive moderation and analytics dashboards for the application.
  • Developed a fully configurable reporting system (operator can choose columns and their types, cross-reference data collections), generating personalized spreadsheets (users, connections, polls) based on raw data from various sources.
Technologies: Netlify, Firebase, Vuetify, Nuxt.js, Vue

Full-stack Developer

2019 - 2021
  • Developed the marketing back office from scratch for the transverse growth team.
  • Delivered personalized news and push notifications to over a million users worldwide.
  • Helped the team successfully launch large targeted marketing campaigns, resolving issues with mobile platforms and payment providers.
Technologies: GitLab, Azure Cosmos DB, Python, Node.js, Nuxt.js, Vue, MongoDB, Azure

Front-end Developer

2019 - 2020
Viking Sasquatch
  • Built front end for pricing engine for the insurance industry. The user interface is fully responsive and offers custom forms and components adapted to the user's needs (price entry, rates and fees calculation, charts, location selection, and more).
  • Helped to recruit, train, and review the work of two younger colleagues.
  • Advised on the progressive web app (PWA) features to be used in the application.
Technologies: Google Cloud, MuleSoft, Vuetify, Nuxt.js, Vue

Front-end Developer

2019 - 2019
Bolt Threads
  • Developed heavily customized eCommerce solution in distributed team.
Technologies: Tailwind CSS, Vue SSR, Nuxt.js, Vue

Senior Application Developer

2018 - 2018
  • Developed personalization and A/B testing solution for enterprise CMS.
Technologies: Git, Elasticsearch, Java

Tech Lead

2018 - 2018
Netseenergy/EDF Group
  • Worked on a microservice migration project for a company in energy efficiency for business and institutional clients sector.
  • Helped to popularize Agile methodology and software engineering best practices, such as test-driven development (TDD), pair programming, and others.
  • Participated in architecture committee meetings to discuss the new data pipeline and microservice platform.
Technologies: GitLab, Git, Oracle, Java


2018 - 2018
  • Developed an application for art galleries, including the back end, web app, and mobile app.
  • Developed a specialized billing module for art galleries.
  • Configured and ran a cloud infrastructure on AWS.
  • Developed CRM module⁠—artist biography, sending catalogs to clients, and export.
Technologies: Amazon Web Services (AWS), Git, Docker, Django

Consultant Software Developer

2017 - 2018
GS1 / Xebia France
  • Developed web-based product barcode management solution.
  • Developed various back-end systems and APIs (Node.js, Java, Python) and front-end interface (Angular 2).
  • Managed cloud infrastructure (AWS EBS, EC2, DynamoDB, Lambda, S3, CloudFront, Route53).
  • Developed efficient Global Trade Item Number (GTIN) generation algorithm (Node.js, Elasticsearch).
  • Presented an introductory talk about Kanban during an internal company conference.
Technologies: Amazon Web Services (AWS), Git, AWS Lambda, Amazon DynamoDB, Amazon EC2, Elasticsearch, Java, Python, Node.js

Scrum Master | Software Developer

2015 - 2017
  • Developed a middle office solution that allows the management of trade allocations, confirmations, and fees for stock market brokerage firms.
  • Worked as a part-time scrum master, facilitating work of a team and helping to improve its development process, focused on functional user stories, reducing WIP, promoting frequent releases, initiating collaboration across departments.
  • Developed client-server application used by big financial institutions (Java, C#, OSGi, IKVM, AssertJ, XML, Gradle).
  • Won ShipIt Day team contest, developing FIX-based post-trade matching solution in 24h. Co-organized Ultimate Bug Fighting Championship.
  • Interviewed candidates for scrum master and back-end developer roles.
  • Promoted Linux in the company by creating and adapting tools, organizing meetups, and maintaining chat channels.
Technologies: FIX Protocol, Git, Java, Agile

Software Developer

2011 - 2015
  • Developed back-end services for API, platform, and mobile teams in a professional social network company with over 50 million worldwide users.
  • Worked with Scrum and Kanban agile development processes and participated in their refinement in a cross-functional team, complete with front- and back-end developers, operations, product, and marketing.
  • Developed a public RESTful API that handles up to 1 million requests per hour.
  • Participated in the development of a brand new service platform under the direct supervision of the architecture team (CQRS, DDD).
  • Implemented a search company into user network functionality (Elasticsearch, Java, Guava, Spring, Cucumber) and address book synchronization, search members by phone number, and job offer suggestions service (Elasticsearch, Java, Spring, Cucumber).
  • Helped to organize the Viadeo API London Hackday event.
  • Temporarily managed the team during the project manager's absence. Responsibilities included planning to meet internal project deadlines, dealing with customer requests, and facilitating inter-team collaboration.
Technologies: Git, JSON, OAuth, Elasticsearch, MySQL, Java

Software Engineer

2009 - 2011
Wood Group Intetech
  • Developed Intetech Well Integrity Toolkit (iWIT) web application for the oil and gas industry in a team of 11 programmers.
  • Redesigned the data source abstraction layer communicating with Oracle, MS SQL Server, web services, PI, and IP2 DBs.
  • Implemented well structure recognition algorithm, reports, and data entry pages.
  • Developed and troubleshot a web service for synchronizing data with a large customer system (JAXWS, JAXB, XML Schema).
  • Introduced Log4J logging framework into the application; configured, wrote extensions, documented and trained others on how to use it, created RSS feed from the application log for testers.
  • Updated the database structure, implemented stored procedures and triggers (Oracle, SQL, PL/SQL).
  • Remotely deployed, configured, troubleshot and profiled iWIT web application on customer test and production virtual servers.
Technologies: JavaScript, CSS, Oracle, SQL, Java

Software Developer

2007 - 2008
CST Technobank
  • Maintained the web framework which provided fundamental functionality to all the company's products for financial institutions.
  • Implemented various framework modules including authorization and authentication, file repository, and tracking.
  • Supervised two student interns developing SSO module.
  • Created user interface widgets, for example, file explorer, panel, and tree that support all major web browsers.
  • Redesigned and reimplemented various components including a controller with centralised input validation and error handling, business logic and internationalization.
Technologies: JavaScript, CSS, SQL, Java

Software Developer

2006 - 2007
  • Co-created a translation memory management web application in a small team within a company specializing in rule-based machine translation.
  • Designed and implemented a bilingual text alignment algorithm (subject of my Master's Thesis) and a rule-based sentence splitting algorithm (rules stored using SRX standard).
  • Created a user interface, controller, data access layer, and installation scripts.
  • Implemented a translator web service.
Technologies: Batch Scripting, Bash, CSS, PostgreSQL, Java


2005 - 2006
Adam Mickiewicz University
  • Worked as a teaching assistant and provided help and support to younger students during practical classes.
Technologies: Java


2004 - 2004
  • Helped to organize the work environment for developers on a project at a customer's site.
Technologies: Linux, Oracle

Sojourner PWA

Free and Open-source Software Developers' European Meeting (FOSDEM) conference companion progressive web app (PWA). Able to store favorite talks in the persistent device storage.

Live version:

Written in Vue.js using VueX, Material Design.


Lightweight web app catalog based on containers, with a user interface à la mobile app store.

The project's goal is to allow the average, tech-oriented user to run web applications without worrying about a server. The idea is to create an easy-to-host, technology-agnostic private cloud.

While many other tools are looking at containers as a way to run massive applications, Puffin concentrates on lightweight ones, each serving just a handful of people.

Wrote using Docker, Python, and Flask.

Live demo: http://puffin.rocks


A popular open-source utility to back up and restore Docker volumes. Written using Docker and Bash. Easy to use, well documented and regularly forked by developers, and used in commercial applications.

Multi-regional company Website

I built a brand new company's website from scratch. It includes four regional variants:
• UK: https://www.wemaintain.co.uk/
• Singapore: https://www.wemaintain.com.sg/

All the content is managed autonomously by the client via Webflow Editor directly or via CMS. The website has a fully functional blog migrated from an existing blogging platform. The website is integrated with Salesforce CRM and contains custom price-calculation forms.

Tech Blog

A place where I publish technical articles about things I've learned at work. Currently, I am focusing on front-end development with Vue.js and Nuxt.js. Recently I started publishing about Webflow and Alpine.js as well.


BurstLogging is a smart logging library that allows emitting detailed debug information in a production environment without polluting the log file with unnecessary messages. During normal operation, only informational messages are logged. However, when an error occurs, previously gathered debug messages are logged as well.

It works by temporarily keeping all log records in a buffer. It preserves their chronological order by dropping debug messages that are older than the recently logged message. There is no huge performance penalty because the message is formatted only when it's emitted.

Written in Python.


This utility starts the given program and reloads it whenever any file in the current directory changes. It can be used as both a Python library and standalone executable independent of programming language.

Written in Python using the Watchdog library.


A tool to split the text into segments, for example, sentences. Splitting rules are read from the SRX config file based on regular expressions.

The tool is optimized for performance, both in terms of processing power and memory consumption (it allows streaming processing). It has been used in commercial, open-source (LanguageTool) and scientific applications to process large text corpora, such as Wikipedia archives.

Written in Java.

I have also co-written a scientific paper based on this tool: https://loomchild.net/files/2013/12/Using_SRX_standard_for_sentence_segmentation_in_LanguageTool.pdf


mALIGNa is a program for aligning documents on the sentence level. It contains implementations of a few groups of alignment algorithms - algorithms based exclusively on the sentence length (Gale and Church, Brown), algorithms based on the connections between words (Moore's algorithm), as well as any variation and intersection of these algorithms. The aim of alignment is to obtain a bilingual corpus. It can be used for creating translation memories, translation by analogy, modeling probabilistic dictionaries, and other applications.

Written in Java. Hosted on Maven central, used in commercial and scientific applications.

I have co-authored a scientific paper based on this tool: https://loomchild.net/files/2013/12/A_new_tool_for_the_bilingual_text_aligning_at_the_sentence_level.pdf


JavaScript, SQL, CSS, HTML, Java, Python, Regex, Bash, TypeScript, SCSS


Vuetify, Nuxt.js, Django, Flask, Vue SSR, Tailwind CSS, Selenium, Ruby on Rails (RoR)


Vue, Vuex, Node.js, Google Apps, SQLAlchemy


Git, Vim Text Editor, GitLab, Amazon CloudFront CDN, Slack, Trello, Confluence, Jira, Auth0, Amazon CloudWatch, Amazon EBS


Agile, Kanban, Scrum, Test-driven Development (TDD), DevOps


Webflow, Docker, Webflow CMS, Azure, Amazon Web Services (AWS), Debian Linux, Firebase, Linux, MuleSoft, Netlify, Ubuntu Linux, AWS Lambda, Oracle, Amazon EC2


Cloud Firestore, Elasticsearch, PostgreSQL, MongoDB, Databases, JSON, Google Cloud, Azure Cosmos DB, Amazon DynamoDB, MySQL, NoSQL, Amazon S3 (AWS S3)


Scrum Master, Progressive Web Applications (PWA), Front-end, Web Applications, APIs, Alpine.js, Computer Science, Firebase Cloud Functions, Architecture, FIX Protocol, OAuth, Batch Scripting, Serverless, Segment, PWA, Cloud Architecture, System Architecture Design, Vue 3, Directus

2002 - 2007

Master's Degree in Computer Science

Adam Mickiewicz University - Poznan, Poland

2004 - 2005

Exchange Student / Socrates-Erasmus Programme in Computer Science

Heinrich Heine University - Duesseldorf, Germany


Certified Scrum Master

Scrum Alliance


Java Programmer (SCJP 6.0) Certificate

Sun / Oracle

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