Leonard Ossa


I love to learn new things and optimize my everyday work, automate daily tasks, and fine-tune tools according to my needs. You can experience this while working with me because I constantly look for things to automate - I create custom internal tools that are speeding up my work - I built many of these in my previous years of employment. I believe in sharing ideas and knowledge so I like creating Knowledge Base at my workplace. I also fancy OSINT and research - I can create a full-blown report with a detailed comparison of available software solutions for the feature you need if you like me to do so. I was leading startup projects including one awarded for creating a working prototype of an innovative mobile ANC device in WAW.ac Technological Startup Accelerator. I also created a smart white-cane prototype for blind people, the invention was mentioned in the Puls Biznesu newspaper. I am into FLOSS software so I also use custom Android (LineageOS) on my phone. I care for privacy and I use privacy-friendly tools. I’d like to learn more in the Software Development area, automation, reverse-engineering and AI.


Senior Software Quality Assurance Engineer, Poly

2022-02 — Present | Python Selenium CI/CD Gitlab

Being part of the architect group that was responsible for desigining and implementing testing framework from scratch. I was one of the main creators of the framework and introduced then implemented novel solutions (like sharing the same code base for an application tested on different platforms). In this position I had to deal with C++ code (that I used in my programming career) and multiple platforms (including iOS, Android, MacOS, Windows, ...) and hardware (headset, webcams, conference devices).

  • Being core of the architect team.
  • Being a mentor/teacher for other coworkers.
  • Introducing new concepts to the team and implementing them
  • Doing a lot of code review and mentorship
  • Setting standards for code quality and maintaining it
  • Doing technical part of candidate interview

QA Engineer, Boldare

2021-08 — 2022-02 | Python Selenium TypeScript Puppeteer

I was part of the team responsible for the development of data-science webapp for external customer. At the team I was using Python and TypeScript for creating tests. I was also published on company website https://www.boldare.com/blog/quality-assurance-for-ux/

QA Tester, T-Mobile

2020-09 — 2021-02 | API Testing Postman REST API Selenium (custom T-mobile fork) Cucumber XPath DevTools OpenAPI Swagger Kiwi TCMS 2FA Django Python Docker Linux servers git Agile

I was solely responsible for designing and implementing the testing process, worked with 3 different teams in two departments. I was the only tester in the department at the moment of joining the team, making myself engaged in the testing process and introducing and integrating that process into the company's procedures according to Agile methodology.

  • Successfully implemented and integrated the testing process into the Agile teams.
  • Created working API health check (based on Postman) that was monitoring API and let developers postpone writing the custom solution and save time. Provided the team with detailed reports from API monitoring.
  • Created an internal side-project based on Microsoft Stream that let employees download and play training videos locally instead of playing them from the website (T-Mobile MS-Stream downloader). That helped people with poor connection quality, so they can watch without video playback stuttering.

Software Engineer, Technica Engineering

2019-12 — 2020-03 | Python pytest Sphinx C# multithreading application IronPython git

Using a mix of technology - including Python, C# and IronPython to write software that parsed, analyzed and processed data based on complex automotive protocols (LIN, CAN, FlexRay). That required learning and a deep understanding of data structure and functioning of industry-specific protocols at the hardware (bit-precisely) level.

  • By changing the previously used threading technique (manual creating&managing threads) to thread pooling I was able to significantly improve the performance of the software (C#). I used the knowledge acquired at one of my previous position at SENSE Software, where I was first introduced to this technique.
  • Wrote custom templates to Python Sphinx, and generated beautiful HTML documentation for a project
  • Wrote documentation for previously undocumented Python code

Manual Tester, Miinto

2019-04 — 2020-10 | SSH DevTools multitail grep tail PostgreSQL bash Linux Redis

Being in the position of Manual Tester while having skills to write bash (but mostly used fish) scripts and automate my work I created an internal custom repository of tools accelerating my work a few times. Scripts I wrote used SSH, some of them run commands remotely on servers or parsed data fetched from servers like script using multitail to grab logs from a few different machines in real-time with highlighting custom syntax specifically wrote for this project.

  • Testing Front-end, investigating bugs and proposing solutions
  • Using PostgreSQL but also NoSQL database - Redis including simple operations on a database
  • Created custom scripts (all of those were internal side-projects) including:
  • Scripts for remote logs scraping , reading and filtering (using multitail)
  • Scripts for remote SQL database updates
  • Designed and implemented an absolutely new solution for tracking testers' tickets that allowed to check which tester was handling a specific customer order
  • Scripts for manipulating Redis database
  • Scripts for interacting with Google Sheets
  • Scripts for deploying environments for testers
  • Providing training for new testers in the team, but also:
  • Recording training sessions and:
  • Creating Knowledge Base for testing team

C# Developer, SENSE Software

2019-01 — 2019-03 | C# .NET multithreading FLIR SDK SVN MVVM WPF - Windows Presentation Foundation Visual Studio

Working in this position I was responsible for implementing new features into the software.

  • I was responsible for implementing parser&interpreter that allowed users to evaluate their own functions in the software (similar to Excel functions).
  • Testing software, investigating, reporting and fixing bugs


Author, A-deck - Chrome extension for A-(dding websites to Nextcloud) Deck

Nextcloud 3rd Party Integration JavaScript DevTools Chrome Extension OwnCloud HTML CSS

This Chrome Extension sends any webpage (current tab) to your Deck on your Nextcloud instance by creating a card. I saw huntr.io board to use for job searching and I thought that's a cool idea, but I want it to be on my server (that's my personal data) and I want to apply this kind of workflow wherever I want, not only to the recruitment process. You can use it anyhow you like now.

Author, Legimi.addToShelf.js

Reverse Engineering API JavaScript DevTools legimi.pl 3rd Party Chrome Snippet HTML CSS

This Chrome snippet adds the 'Add to Shelf' button while viewing legimi.pl catalogue. It was developed because the official web front-end impose on you to open every book website in order to add it to your shelf. With this extension, you can add books to the shelf from the main catalogue without opening links for each book.

Author, High-Performance-Eleventy-Garden

JavaScript HTML CSS

This project aims to apply performance features from eleventy-high-performance-blog into Eleventy-Garden, additionally, I added Rough Notation because I think it is cool. Now I'm planning to add more features and use it as a second-brain / digital garden / zettelkasten.

Author, AlternativeTo.net - OnePager - bookmarklet

JavaScript DevTools alternativeto.net bookmarklet HTML CSS

This bookmarklet is for fetching&displaying all items on AlternativeTo.net on one page.

Contributor, Add to Shaarli

Shaarli 3rd Party Chrome Extension JavaScript HTML CSS

Added new features to the "Add to Shaarli" Extension. I was using Shaarli on my server as a bookmark keeping solution and I needed to have more functionality using Chrome Extension.

Author, LinkedIn Video Downloader - bookmarklet

LinkedIn Learning 3rd Party Bookmarklet JavaScript HTML CSS

This bookmarklet allows you to easily download LinkedIn Learning videos.

Author, Nogopho

Python scrapy

This project aims to compare all the mobile OS systems alternatives to Google Android. For now, it's just scraping websites with scrapy.


Added suggestion to PowerShell official repository


Contributing in PowerShell repository by adding suggestion to change PowerShell building script on Linux. This local modification of my own let me build PowerShell on the machine running Linux Mint.

Opening issues in Wallabag Android App repository


By using Wallabag on my own server with the Android App I found issues with some URLs that app could not handle well

Opening issues in FrontendMasters Android repository


Suggestions for FrontendMasters Android app.


Tabu choroby pracownika czyli jak wyleczyłem nieuleczalną chorobę, LinkedIn.com


Article in Polish language describing how I managed to cure myself out of incurable disease helping myself by removing obstacles from my proffessional life.

Kwarantanna to zły pomysł, czyli ile żyć możemy zniszczyć aby jedno uratować?, LinkedIn.com


Article in Polish language comparing moral decision by Artificial Intelligence driven cars on choosing whom to save and whom to kill on the road with decision to impose lockdown

Google jest głupi, a Elon Musk się myli, czyli o co właściwie chodzi z tą Sztuczną Inteligencją?, LinkedIn.com


Article in Polish language describing what actually so called 'AI' is and how does it work and why headlines you read about AI are wrong

​What happened in WAW.ac won’t stay in WAW.ac (czyli co się stało w WAW.ac, nie pozostanie w WAW.ac), WAW.ac - Warsaw technical start-up accelerator


Review of WAW.ac technical start-up accelerator (Polish)


Main prize for the best startup project, WAW.ac - Warsaw Technological Startup Accelerator with hub:raum T-Mobile


Prize was for inventing, building and presenting working prototype of 'Husher' - mobile ANC (Active Noise Cancellation) device. The whole process from idea to present working prototype took around 4 days.


Arantxa Fernandez, Team Leader

Link to full document

Krzysztof Czarnecki, Coworker

Contact information available on request.


Cognitive science and neuroscience


I'm deeply fascinated with brain and its capabilities. I read a lot about mind, intelligence (human and animal one) and methods to improve intellectual functioning.



Biohacking allows me to live healthier and more productive life on every day basis.