Technical Co-founder
2014 - PRESENTxltrail- Developed a web app on top of Git that facilitates version control and collaboration for Excel.
- Built the first iteration and brought it to market. The app is used by on-premise and Cloud customers, primarily in the financial services industry. The app supports various deployment targets: Cloud, on-premise, and airgapped on-premise and integrates with enterprise LDAP/AD systems for user (and licensed seats) management.
Technologies: PythonPython Developer
2012 - PRESENTFreelance Financial Technology Consulting- Developed bespoke Python-based solutions to a number of clients in the financial services industry (hedge funds, asset managers, trading desks), primarily in London and Zurich.
- Built Celery-based apps for scheduling complex asynchronous workflows-long-running calculations as well as highly concurrent data flows to and from third-party systems (Bloomberg). Leveraged Django, Flask, SQLALchemy, and Falcon to deliver REST APIs.
- Delivered containerized apps for easy CI/CD and deployment, leveraging GitLab pipelines.
- Integrated legacy Excel/VBA applications with client-side Python code (via xlwings), server-side REST APIs and Bloomberg (via BLPAPI and Data License).
- Integrated Django/Flask REST apps with customer's LDAP/Active Directory infrastructure for authentication and authorisation.
- Helped customers integrate and replace Excel with Jupyter notebooks.
Technologies: PythonRapid Application Development Consultant
2014 - 2016Credit Suisse- Developed a number of tactical Python solutions for the equity trading desks in London.
- Integrated legacy Excel applications with modern REST APIs.
- Spearheaded a data science project to extract historical quantitative data from non-structured data using Pandas.
- Built various rapid application Excel/VBA applications.
Technologies: C#, PythonQuant and Rapid Application Developer
2006 - 2012UBS Investment Bank- Developed a new platform for the bank's commodity index business that enabled them to better risk-manage their complex trading book.
- Built a Python-based backtesting platform that enabled users to rapidly prototype and launch new alpha- and beta trading strategies.
- Oversaw and managed new product launches resulting in additional revenues to the business.
- Introduced Excel-DNA to rapidly build Excel Add-Ins in C#, facilitating a modern integration between Excel and internal REST APIs and Bloomberg's BLPAPI.
Technologies: C#, PythonJunior Risk Controller
2005 - 2006Landesbank Berlin- Developed a suite of C++ and Excel-based tools improving the bank's ability to monitor the risk of its equity derivative portfolio.
- Integrated internal (Murex) and external data feeds (Bloomberg) into the risk system.
- Streamlined the department's internal RFC process to ensure a faster and higher quality release process.
Technologies: C++, Microsoft Excel
Bjorn Stiel
Software Developer in London, United Kingdom
Member since December 5, 2019
Bjorn is a senior Python developer who spent over a decade building robust and scalable applications for clients such as Credit Suisse. He specializes in distributed workflows via Celery and REST APIs using Django, Flask, and Falcon. He developed an app for UBS Investment Bank that helped their trading desks manage multi-billion dollar risk. Bjorn's expertise with complex integrations prove invaluable in projects where precision matters most.
Bjorn is now available for hire
Portfolio
- xltrailPython
- Freelance Financial Technology ConsultingPython
- Credit SuisseC#, Python
Experience
- Python 15 years
- Flask 10 years
- SQLAlchemy 8 years
- Celery 8 years
- Docker 5 years
- Django 4 years
- Django REST Framework 4 years
- Falcon 3 years
Availability
Part-time
Preferred Environment
Windows, Linux, Docker, Visual Studio Code
The most amazing...
...app I've developed makes Excel workbook files work seamlessly with Git.
Employment
Experience
- Version Control and Collaboration App for Excelhttp://www.xltrail.com
A Python-based web app that makes Excel workbooks work with Git. I was the back-end developer integrating many moving parts: Celery to do the heavy lifting and execute long-running background tasks, libgit2 for integrating Git, and Falcon to expose the REST API. The app is fully dockerized, which allows for a smooth multi-target (single-tenant on-premise and multi-tenant Cloud) deployment process.
- xlwings - Python for Excelhttps://www.xlwings.org/
xlwings is an open-source Python library that makes it easy to call Python from Excel and vice-versa. It is developed on top of Git, facilitating version control and collaboration for Excel. The app is used by on-premise and Cloud customers, primarily in the financial services industry.
Skills
Languages
Python, Falcon, Excel VBA, C#, C++Frameworks
Flask, Django, Django REST FrameworkLibraries/APIs
SQLAlchemy, Bloomberg APITools
Celery, Git, Microsoft Excel, Excel-DNA, Excel 2016, Docker Compose, PytestPlatforms
Docker, Jupyter Notebook, Visual Studio Code, Linux, Windows, KubernetesOther
xlwings, LDAPStorage
PostgreSQL
Education
- Master's Degree in Financial Engineering2006 - 2008Birkbeck College, University of London - London, United Kingdom
- Master's Degree in Business Economics2000 - 2005Free University of Berlin - Berlin, Germany
