Open Source has been part of the Zalando journey since the very beginning 10 years ago. Open source has served us well, and ensured that our engineering teams have had great tools and frameworks to their disposal to build and scale the systems supporting the business.
Because of this legacy, we believe it is important that we contribute back to the open source community with projects that can benefit others, helping others to move forward, benefit from our experiences and investment benefits us all - as the old saying goes, a rising tide lifts all boats.

In 2018, 25 new projects were added to the Zalando GitHub organizations. Combined, all Zalando projects saw nearly 5.000 pull requests, with 31% coming from non-employees. In total 11.239 commits were made and our projects generated 357 releases in 2018.

...The challenge faced by the Open Source Team is to take the current goodwill around Zalando’s open source work and professionalize it. This will enable Zalando to use and create open source in a consistent manner. With consistency, we can scale and streamline our open source activities and evaluate their impact and value, ensuring they are aligned with Zalando’s longer-term vision...

Key Insights

  • Increased Activity On New Projects

    We released 25 new projects in 2018, this is a slight increase compared to 2017. However the average level of activity in the form of pull requests in the first 12 months have increased from 17 to 34 per project.

  • Open Source Part Of Engineering Onboarding

    Since October 2018, the open source team have conducted mandatory training for all new engineers joining the company. 100 engineers have received training so far.

  • Code Of Conduct Is Now Mandatory

    In November we introduced the use of Code of conduct files on all new projects being released and are working on introducing this across all public projects. We believe it is an important first step towards a friendlier and more diverse open source community.

  • Machine Learning And Infrastructure Focus

    Machine Learning and Kubernetes are both areas which Zalando heavily relies on and invests in. Projects related to these topics have seen great adoption outside of Zalando

  • External Contribution Is Growing

    Throughout 2018 we've registered an increased contribution from external developers, increasing the number and diversity of contributors is one of our key goals to ensure that projects are sustainable and healthy.

  • Guidance can increase project visibility

    We introduced the open source promotion framework that acts as an idea catalogue to help project teams grow visibility and increae contributions from the community. One of the most successful cases of this work was the Flair project which gained almost 4000 stars, 241 forks, and became a trending repository on github.

Work done in 2018...

2018 has by design had fewer releases than in the high activity years of 2015 and 2016. However, all other activity indicators are higher than any previous year. Releases, Pull Requests, Commits and contributions from external sources have all increased compared to 2017.


New Projects


New Commits


Pull Requests Created


New Releases

Work done on our open source projects in 2018

Community and contribution


Of our org members are contributing

Out of the current 510 people in Zalando organisations on GitHub, half of them have made an accepted code contribution to a Zalando open source project - this is a 4% increase since June 2018.


Community contributions

For all current projects, 31% of all pull requests are from non-employees.


Contributions made to techradar projects

Zalandos contributed to 18 projects on the Techradar "Adopt" tier, which are part of our tech stack and have a high strategic value to Zalando

91 Hours

Average time to get a pull request merged

The average response time to pull requests have increased from 85 hours to 91, the number is within an acceptable response time.

Open source activity by Zalando employees (purple) is at a overall stable level with seasonal variations (summer holidays and the run up to black friday are typical low-activity periods). We are however seeing a positive increase in External contribution (blue) to our projects. The single big spike in the chart above is caused by a GitHub bot doing over 100 automated pull requests.

Our goal for responding to pull requests is 80 hours, this includes weekends and holidays, we generally succeed at keeping our reponse time at a satisfactory level for pull requests by employees but are seeing spikes more often for external contributions. Average across all pull requests is 91 hours. Unfortunately, this year we had 45 contributions which did not see a response in over 100 days.

Top contributors in 2018

While open source is encouraged at Zalando, it is a small number of contributors who drives the majority of all open source contributions. Just 17 Zalando employees are responsible for 50% of all commits made, and 80% of all open sourced Zalando code is contributed by 50 employees.

  • Willi Schönborn

    1193 commits
  • Mikkel Oscar

    529 commits
  • Alan Akbik

    472 commits
  • Alexey Ermakov

    371 commits
  • Sandor Szuecs

    371 commits

What we share

New releases in 2018 included 3 projects focused on machine learning: Flair, a natural language processing framework built on top of Pytorch. Famos, an adversarial framework for image stylization and Darty, a data dependency manager.

3 projects related to our work with Kubernetes was released during 2018: Cluster-lifecycle-manager, to provision multiple kubernetes clusters, Stackset-controller, a kubernetes resource lifecycle manager and Kube-metrics-adapter for Kubernetes HPA metrics collection.

The Zalando open source team released documentation and tooling for managing and releasing open source projects: Roadblock and Trafficlight.

Most Popular Projects

As technology and trends shift, we see the average activity for a project drop after 24 months to a generally lower level. After approximately 45 months this drops further as many of our projects enter a state of decline or maintenance mode. This is in line with the general trend of open source project activity.

Past 6 months

The past 6 months, the Open Source team has been focused on creating clearity of Zalando open source policies, remove barriers of entry and spread the culture of open source among current maintainers and new hires. The list below is the open source team's roadmap for second half of 2018 along with a status of each task.

Single source of truth - done
Restructure and clearify process and policy documents to remove any uncertainty of Zalandos open source strategy

Website launched May 2018 - updated on a weekly basis
GitHub restructure - done
Focus on clear project ownership, compliant workflows and a simpler organisation of project maintainers.

Restructure completed August 2018
Onboarding program - done
Deliver open source onboarding program for all new tech hires

Training program initiated October 2018 for all new tech hires
Increase our presence - Ongoing
Systematic approach to introducing new open source projects to the world and promote current initiatives and the teams behind them

New project incubation process introduced in September 2018, promotion framework piloted November 2018
Maintainer training - In progress
Project maintainer training on building community and being a great open source citizen

First round of project maintainer training in January 2019 - mandatory for all new projects
Policy and Rules Of Play - Not complete
Align our policies to remove barriers and uncertainty. Work with legal, compliance and Zonar teams to improve our polices and legal contracts

While internal developer ruleset has been updated we still see room for improvements in regards to how ownership and copyright is managed


Top priorities for the open source team in the coming 6 months.

Measure and act on project maturity
Leverage open source governance to ensure consistency and professionalism across Zalando open source projects. Introduce project maturity model as a guide for adoption and growth assessment.
Project Maintainer Training
Launch maintainer training to increase the level of knowledge and number of open source experts within the company.
Giving Back
Continue to push contributions to upstream projects and release high-quality work back to open source community. Encourage engineering leaders to hire community contributors
Launch InnerSource Program with measurable impacts on delivery time.
Open Source Ecosystem
Grow open source ecosystem internally and externally: bi-monthly open source guild event, open source review group meetings.

Published By The Zalando Open Source Team

All the statistics mentioned in this report are collected through Roadblock