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Hi, I am Jonathan Sundqvist

Freelance full-stack developer with a focus on Python

I enjoy building robust web applications using my experience in JavaScript and Python. If you need a Software Engineer with many years of experience in Django and other Python frameworks, who additionally, knows their way around frontend development, I'd love to hear from you!

I'm currently available for at most 2 days per week.
Or sign up to be the first to hear when I have more availability.

Jonathan Sundqvist
About my work

10+ years of online experience as a Python developer

I'm a backend developer with a solid foundation in frontend development. I'm take a unified approach to backend and frontend, leading to less complex application architecture.

Backend Development

I have extensive knowledge of Python, API architecture, and various Python frameworks. I particularly enjoy working with the Django framework. However, I'm more than happy to take on projects using pure python, FastAPI, or any other framework.

Frontend Development

My preferred approach for frontend development is to stick closely to browser standards. When building interactive application components, I think the better approach is using modular web components rather than a monolithic JavaScript framework.

Design mockups
Curriculum Vitae

I've worked for many great organizations

From international startups to large organizations such as Fidelity Investments.

Senior Software Engineer, freelance

Recorded Future, Remote

July 2020 - Present

CSS, JavaScript, Flask, FastAPI, Lit, Python, Splunk, stimulus.js, Sentry.

Tooling

CSS, JavaScript, Flask, FastAPI, Lit, Python, Splunk, stimulus.js, Sentry.

Work & Responsibilities

  • Initiated the practice of code reviews, linting, and ensuring that tests run when opening a PR.
  • Led major refactor of Splunk application which included a new frontend and a new API built in Flask.
  • Identified bottlenecks that led to a transition of the API to FastAPI.
  • Architected the migration from Flask to FastAPI to make it gradual, enabling work on migration and new features.
  • Reduced API response time by 95% (from 2-3s to <100ms) through caching, streaming and migrating to FastAPI.
  • The backend application the team built streams several gigabytes every 5 minutes.

Senior Software Engineer, freelance

Surfgreen GmbH, Remote

June 2024 - Present

CSS, Django, Javascript, Python, PostgreSQL, Sentry, Vue.js

Tooling

CSS, Django, Javascript, Python, PostgreSQL, Sentry, Vue.js

Work & Responsibilities

  • Reduced test suite runtime from 1 hour to 3 minutes.
  • Identified and fixed significantly slow queries.
  • Updated several years' worth of old dependencies to new versions.

Senior Software Engineer, freelance

Mont Blu, Remote

April 2025

CSS, JavaScript, HTML, static site generation

Tooling

CSS, JavaScript, HTML, static site generation

Work & Responsibilities

  • Built Votimetro from the ground up in 40h.
  • Maintained tight communication with Mont Blu to get the project up and running during a crucial time.
  • Made it a critical success.

Senior Software Engineer, freelance

Fidelity International, Frankfurt

August 2019 - April 2020

Django, Django-CMS, Python, CSS, HTML

Tooling

Django, Django-CMS, Python, CSS, HTML

Work & Responsibilities

  • Built open source Django-CMS plugins.
  • Enabling migration of legacy CMS to Django-CMS.
  • Quickly identified gaps in user experience and new bugs to be fixed for the migration to succeed.
  • Enabling migration of legacy CMS to Django-CMS.
  • Completed numerous Public Pull Requests during the above period

Software Engineer

Zageno GmbH, Berlin

May 2017 - April 2019

Django, HTML, CSS, Python, PostgreSQL

Tooling

Django, HTML, CSS, Python, PostgreSQL

Work & Responsibilities

  • Built punchout integrations enabling customers to log in and purchase products through their procurement application such as Oracle or SAP.
  • Built an upload tool handling 100k of uploaded entries every day.
  • Developed an algorithm that matched uploaded entries with existing entries.
  • Produced technical requirements and architecture for both of these projects.
  • Mentored of a junior colleague from no python knowledge to becoming a contributing member in the tech team.
  • Optimized database queries written in Django's ORM.

Junior Software Engineer

Server Density, London

November 2014 - March 2017

Python, PHP, JavaScript, WordPress, Google App Engine

Tooling

Python, PHP, JavaScript, WordPress, Google App Engine

Work & Responsibilities

  • Developed projects in tandem with the Marketing team.
  • Integrated and reversed-engineered third-party party APIs for Server Density's usage.
  • Worked on an internal customer system deployed on Google App Engine.
  • Wrote API wrapper for Server Density's public APIs.

Five things you probably would like to know from me

Are you available for an interesting position?

Right now I'm available for two days per week, or for shorter engagements, however, that will require some planning ahead.

Do you want to employ me? Make me an offer impossible to resist!

What's your hourly rate?

My hourly rate is €95 per hour.

Do you have experience with <technology X>?

I'm used to to pick up new tools and techniques. Are you looking for a specific skill? Please contact me to see if I can help you with that!

Where are you located? Do you work remotely?

I'm located in the southern part of Germany, close to the border of Switzerland and France. Is that too far away from you? No problem, I've been working remotely for years.

An arrangement where I visit the office for a week every other month or similar would also be possible.

What is this web page/site built with?

This web page is hand-coded with love in plain old vanilla HTML and CSS, with some sprinkled JavaScript on top. argpar.se is otherwise using the static site generator Pelican.

Ready to discuss your project? Let's schedule a call to see how I can help.
Just want to chat? Shoot me an email about what you want to chat about!