Martijn Pieters
Open Source Consultant at Zopatista
Cambridge, England, United Kingdom
Summary
🤩
Rockstar🎓
Top SchoolMartijn Pieters is an Open Source consultant and seasoned software engineer with roughly 20 years of professional experience and nearly three decades of programming expertise. Based in Cambridge, he blends deep Python knowledge—reflected by his #1 ranking for Python answers on Stack Overflow—with pragmatic system design for scalable APIs, data pipelines, and high-throughput services. He has driven large engineering efforts at Facebook (scaling Mercurial and source-control services) and led architecture and mentoring work for startups and enterprises, including CDN, ML production pipelines, and real-time data platforms. An active contributor to core Python projects and major libraries (cpython, typeshed, httpx, requests, apispec, and Apache Airflow), he focuses on type safety, static analysis, and robust testing to improve code quality across ecosystems. Martijn’s consultancy work pairs hands-on implementation with team enablement—mentoring, code reviews, and training—so clients leave with both working systems and better engineering practices. Less obvious: he often tackles thorny edge cases (encoding, serialization, and tooling around large repositories) that quietly improve reliability at scale.
20 years of coding experience
17 years of employment as a software developer
Msc IT, Msc IT at University of LiverpoolComputer Science, Computer Science at Delft University of Technology
Dutch, English, Norwegian, German, French
Stackoverflow
1,083,587reputation
167.6mreached
19,919answers
3questions
pandas
top-1%
filtering
top-5%
oop
top-1%
while-loop
top-1%
type-conversion
top-1%
encoding
top-1%
Github Skills (200)
multithreading10
python-datetime10
testing10
psycopg10
csrf10
url-parsing10
boolean10
if-statement10
ubuntu10
automation10
db-schema10
encoding10
ascii10
async-await10
syntaxerror10
Programming languages (28)
Github contributions (5)
aio-libs/yarl
Mar 2022 - Dec 2022
Yet another URL library
Role in this project:
Backend Developer
Backend DeveloperContributions:13 reviews, 11 commits, 92 PRs in 8 months
Contributions summary:Martijn primarily contributed to the `yarl` library by addressing issues, improving code quality, and adding new features related to URL manipulation. They fixed bugs associated with outdated git protocols and `black` code formatting. Furthermore, they added the `joinpath` feature which helps in building URLs with multiple path elements. The user also updated dependencies and made documentation improvements.
urlsaiohttpurl-parsingyet-anothertinyurl
psf/requests
Oct 2012 - Aug 2015
A simple, yet elegant, HTTP library.
Role in this project:Back-end Developer
Back-end DeveloperContributions:12 commits, 2 PRs, 14 comments in 2 years 10 months
Contributions summary:Martijn primarily focused on improving the `requests` library's handling of JSON responses, specifically addressing encoding detection and fallback mechanisms when no explicit encoding is set. They implemented a JSON-specific encoding detection mechanism that complies with RFC 4627. Additionally, the user corrected a copy-paste mistake in the tests and added the user's username in the `AUTHORS.rst` file. The user also fixed the smoke test for UTF-16 and removed unnecessary logging and chardet references.
http-librarypythonhttp-clientjavascriptpython-requests
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