STEFAN ZHELYAZKOV
Software Engineer
Bachelor of Science in Engineering with Computer Science, UPenn 2013.
Employment
Associate Software Architect
2022 - nowMusala Soft, Bulgaria
Lead Software Engineer
2021 - 2022Senior Software Engineer
2020 - 2021- Working on an enterprise solution at SAP Labs Bulgaria for a system that stores and validates trust for collections of artifacts using cryptography.
- Managing the team behind the international programming competition CodeIT: https://codeit.bg/eng.
- Participating in the recruiting efforts of the company.
Software Engineer
2018 - 2019WeWork, New York, NY
- Worked on an application for the furniture inventory of the company. I used Kotlin, Spring, Hibernate, REST, React, TypeScript. I was responsible for the backend architecture, database management, REST API, soft delete infrastructure, speed optimizations, security, tests.
- Initiated a library for DAO objects which makes communicating with the database easier, including working with transactions. The library was shared with other internal teams and received good feedback which helped for its integration in the common backend libraries of the department.
- Worked with a summer intern whose project was successfully integrated into production
Software Engineer
2016 - 2018Honest Buildings, New York, NY
- Developed most of the first Reporting & Exporting tool - complex and efficient DB queries, in-screen data formatting, coloring, highlighting, filtering, saving, and exporting to Excel. I used Java 8, Dropwizard, AngularJS 1.6, JavaScript, jOOQ.
- Actively contributed to a stronger backend architecture. Initiated and contributed to the separation of the services layer from the endpoints.
- Refactored and cleaned legacy code, resolved bugs and helped increase code coverage.
- Helped introduce a Java linter and a stylechecker
- Regularly updated some of our major BE library dependencies and performed code uplifting accordingly
Technology Analyst
2013 - 2016Goldman Sachs, New York, NY
Worked on business applications for the Credit Risk team:
- Java back-end applications aggregating GB's of data and producing Credit Risk metrics. Worked on the full flow from sourcing, transforming, aggregating, displaying and storing the data. Optimized the legacy codebase. Documented it. Sped up certain processes by up to 14%.
- Adapted several large Java applications (60GB RAM ~ 120GB) to run on a new grid of servers thus helping reduce maintenance costs. This work resulted in annual savings between $100,000 - $200,000.
- Actively worked with interns and other junior people. Participated in the recruiting efforts of the company, including the firmwide Hackathon Recruiting Committee for 2015/2016.
Education
University of Pennsylvania
2009 - 2013Bachelor of Science in Engineering Cum Laude
Graduated with a Bachelor of Science in Engineering degree in Computer Science in May 2013. Minors in Mathematics and Science, Technology & Society.
Romain Rolland FLS
2004 - 2009Stara Zagora, Bulgaria
Graduated from Romain Rolland Foreign Language School. Areas of concetration: English, German, Mathematics and Literature.
Programming Languages
Java/Java 8+
Kotlin
Go
JavaScript/TS
PHP + MySQL
Haskell, OCaml
C/C++, Python
Tools & Technologies
Spring
Dropwizard
React
AngularJS
Docker
JUnit 4/5
jOOQ
Mockito
Git/SVN
Gradle/Maven
Speaks
Bulgarian
English
German
RPi4 Tablet 2
Hardware
The power of JWT and cryptography
Video
RPi4 Tablet
Hardware
listcerts.com
Website
IPCC Sixth Assessment Report in Bulgarian
Video
The Voice of Bulgaria 2020 on YouTube
Website
Can & Sanem
Video
beeTV Plus
Mobile
World 2037
Website
Reading Music From Images
Course Project
wxReversi
Course Project
JamSesh
Website
Lia
Course Project
WineSquare
Website
Superscalar Processor
Course Project
Lemonlime
Website
MixMaster
Mobile
MyTube
Course Project
PennOS
Course Project
OAT Compiler
Course Project
PennQuiz
Course Project
PyPlay
Course Project
Biblioteka
Mobile
Breakout
Course Project
SpaceInvaders
Course ProjectCertificates
Building Cloud Services with the Java Spring Framework Oct 2019
Vanderbilt University
Credential ID QUJF6REB8VK3
Front-End Web Development with React Nov 2018
The Hong Kong University of Science and Technology
Credential ID WERHEH5WYVUD
Algorithms: Design and Analysis, Part 2 May 2015
Stanford University
Algorithms: Design and Analysis, Part 1 Dec 2014
Stanford University
Functional Programming Principles in Scala Jun 2014
École Polytechnique Fédérale de Lausanne
Papers
Authors
Reading Music From Images 2013
Department of Computer Science, University of Pennsylvania
From a historical perspective, there have been many scientific attempts to find a relationship between images and music with respect to the emotions that both subjects evoke. In modern times, these scientific efforts have been facilitated by the use of computers aiming to discover evidence for objective correspondence between visual and audible information. Based on existing research, this research is targeted to analyze currently used algorithms for reading music from images by comparing their output based on feedback from a pool of testers. The second goal is to provide an improved algorithm for conversion of images into music that will extend on the algorithms analyzed in the experiments. This is a process that uses the results of two existing algorithms in the design of a third algorithm, Extended Chromatic Analysis.
Статистически анализ на шампионатните отличия на българските футболни отбори 2013
Individual
Настоящето изследване разглежда националните отличия на българските футболни отбори в родното първенство. Главните категории на статистическия анализ са брой отличия от официални и неофициални турнири, класифициране на трофеите, които се считат за Национална купа, разпределение на клубните отличия по градове, анализиране на коефициента на успеваемост на българските отбори, подробен анализ на успеваемостта на "ПФК Левски (София)", "ПФК ЦСКА (София)" и "ПФК Лудогорец (Разград)" и последно - анализ на дубълите и требълите на българските футболни отбори. Статистическите данни са изложени в раздел "Статистика". Преди това е представена кратка история на българския футбол, обяснения по официалните трофейни турнири и пълен списък на 26-те отбора, които са печелили национални отличия. Изследването завършва със секция, която обобщава резултатите, и представя няколко интересни факта. Изследването не е рецензирано и е отворено за дискусии и по-нататъшни корекции и надграждания.