Mark Koester

Personal Blog. A Data-Driven Life. Minding the Interstitial Spaces since 2007.

Products, Projects and Creations by Mark Koester

UPDATED: JULY 20, 2019

Besides my client facing development business, I’ve built and helped on a number of products and services over the years. The majority are open source with a focus on data and self-tracking.

Here is a list of most of them, including the active ones as well as a few that didn’t quite make it.

My Active Projects and Products (Web)


WHAT IS IT: This website and project is dedicated to transforming science, self-tracking and data into better self-understanding and empowered self-improvement. Current focus is on content creation, including blog posts, tracking guides and our first learning course, Quantified Self 101.

STATUS / WHAT’S NEXT ONE DAY: Current primary focus learning resources and course creation. After first course is release, I hope to expand into courses on data analysis and visualization using Google Data Studio, Python and other tools and languages. Long-term I’d like to create a robust QS, data-driven dashboard and self-experimentation product. (iOS + Android)


WHAT IS IT: PhotoStats is an iOS and Android app that lets you track your photos without depending on external services. The app keeps a log of your photo history, enables you to use Machine Learning and Artificial Intelligence to tag and label your photo library automatically, and provides a bunch of visualizations to see your photo taking over time. Learn insights over time. Your photo data can tell a story. We help you do it.

STATUS / WHAT’S NEXT ONE DAY: The current version of the app, built in React Native, is stable and actively used on iOS and Android. I’d like to expand it to provide better search by tags and richer reports. Perhaps one day we can do a mood tracking, personality tests, or somethign else based on your photos. (Web)


WHAT IS IT: Podcast Tracker is a web service to track your podcast listening, view your basic stats and export your podcast listening history. It has several hundred users and thousands of podcasts and episodes.

STATUS / WHAT’S NEXT ONE DAY: Current version was built in Drupal 7 and remains active and maintained with daily users. I plan to do a full rebuild one day likely in Python with an API-first approach and integrated into existing podcast listening apps (or maybe one day build our own app for passive tracking).

QS Ledger (Python)


WHAT IS IT: A Personal Data Aggregator and Dashboard for Self-Trackers and Quantified Self Enthusiasts. Currently integrates over 20 self-tracking services, including Strava, Todoist, RescueTime, Fitbit, Instapaper and many others. This python-based project contains dozens of Jupyter Notebooks and aims to be the go-to location for data collection and data visualization for self-trackers!

STATUS / WHAT’S NEXT ONE DAY: This is one of the most active open source project I hack on in my free time. It has over a hundred github stars now too. I plan to add or update some of the integrations and tightening the visualization aspects. I’d like to improve the beginner documentation and on-boarding. The next big steps aim at deeper analysis using statistical and. time series analysis as well as more machine learning and deep learning techniques.

Awesome Biomarkers


WHAT IS IT: Curated List of Biomarkers, Blood Tests, and Blood Tracking. Learn more about blood testing, biomarkers and tech and services to help quantify (and improve) your health! It currently includes several dozen common blood tests results.

STATUS / WHAT’S NEXT ONE DAY: My ultimate aim is to provide an open source and community database on and about biomarkers. That way we can build great technologies for individuals, companies and communities hoping to use biomarkers and health metrics to power their solutions. In the short-term I hope to provide reference ranges, more references to research papers and ideally a simple tool for checking latest labs. Long-term we need to explainable ML and AI that translate our blood tests and biomarkers into predictions and recommendations.


WHAT IS IT: Website to export and download your completed tasks history from Built using Python and Flask and integrated with Todoist API.

STATUS / WHAT’S NEXT ONE DAY: Largely built as a way to learn improvement my python and flask skills, I hope to expland it one day to include more charts, graphs and analytics.

NOTE: An Open Source Version is also available here:

Drupal Modules


WHAT IS IT: Since learning to use Drupal in early 2010s, I’ve created and open sourced over 50 modules and themes on Most notable are Quizlet, Events Distribution, Flag Limiter, Toolbar Message, and Joyide of D7 among others.

STATUS / WHAT’S NEXT ONE DAY: While these modules are still used actively on hundreds of sites, I no longer actively develop them outside of client and paid requests.

Legacy Stuff I’ve Built

  • BioMarkerTracker - Intended as a followup to Awesome Biomarkers DB, this apps aimed to a data-driven tool to help people understand, assess and take positive actions to improve their health. Still might resurface this one day but for now dev has stopped.
  • - Interactive CMS for language learning and teaching. Active from 2010 to 2012 and served over a dozen teachers and several hundred students.