How Zalando uses GitHub

Zalando uses GitHub to facilitate collaboration and prioritize open source contributions.

Hero image for the story: Zalando

Company Overview

Industry: eCommerce
Number of Seats: 3,000
Customer Since: 2015

Founded in 2008 by university friends Robert Gentz and David Schneider, Zalando began as a Berlin-based sneaker delivery service. Today, the company offers over 600,000 fashion and lifestyle products to 34 million active customers across 17 European markets. With 14,000 employees—including 1,600 developers spread over 200 teams—Zalando generated €6.5 billion in revenue in 2019.

Consolidating Development Tools

Teams initially used both GitHub and Bitbucket, but the decentralized systems slowed delivery. In 2015, Zalando challenged teams to adopt whichever tool accelerated their work. "We looked at the adoption rate, and it was exponentially higher for GitHub Enterprise," said Engineering Lead Kay Goebel. "People were very happy to move."

Today, Zalando is cloud-only, using Amazon Web Services for infrastructure and GitHub for source code management. "Every single engineer at Zalando uses GitHub Enterprise."

Zalando: Meeting

Collaboration and Project Management

Kay and his team maintain Zalando's GitHub Enterprise installation and ecosystem, including tooling and onboarding. They focus on increasing code collaboration, efficiency, and productivity. "GitHub is not only our code repository. Issues are also our project management tool and repos are the one place where everybody collaborates together."

The team uses the GitHub API for metadata enhancements and creates automation bots for pull request merging and reminders. Combined with ZenHub for agile project management within GitHub, this setup has increased visibility across departments.

"People can collaborate and share code, regardless of what other tools they're using," said Kay. Engineers can use their preferred development environments—whether IntelliJ, Atom, or Linux with Vim—while code reviews happen in a single cohesive environment. "It all happens in a central place and nobody has to sacrifice their preferred tooling."

Zalando: Developers

Measuring DevOps Performance

Kay's team leverages the GitHub API to implement a strategy from Accelerate: The Science of Lean Software and DevOps, which outlines the correlation between DevOps metrics and organizational performance. Zalando gathers and displays four key performance indicators:

Mean time to repair
Lead time
Change failure rate
Deploy frequency

These KPIs are made easily accessible in a portal, allowing teams to see the impact on delivery when releasing new features. For example, using CI/CD features increased deployment frequency. The data also helps track applications deployed in the past to ensure they remain healthy. "Having this kind of information available helps people understand if and where they need to invest," said Tim Kröger, Head of Developer Productivity.

Zalando: Office Dog

Security and Compliance

To maintain security and compliance, Zalando uses Dependabot and integrates static code analyzer tools with GitHub Enterprise and the deployment workflow. "We also use vulnerability reports from GitHub and GitHub Connect for dependency scanning," Kay said.

The company employs an "immutable deployment concept," preventing manual changes after code goes live. "Everything that merges from the pull request gets automatically deployed live without any manual working steps to ensure instance compliance."

Open Source Strategy

Zalando has relied on open source software from the beginning, leveraging it to start and scale the company. "Basically everything we build is iterating on open source," said Kay. "I think it's only reasonable for a larger organization like us to engage and give back to the community where possible."

Zalando's open source philosophy is three-fold: participate, share, and promote. All open source projects must meet five requirements: high quality, well-documented, secure, actively maintained, and used by the broader community. Everyone on the team has a responsibility to respect licenses and adopt mature projects.

Zalando: Headquarters

Zalando currently maintains 201 active open source projects written in 16 different languages, with 32,039 stars and 927 active contributors. The company's onboarding process includes a session focused solely on open source, and engineers are expected to contribute back to the projects they use.

Notable Open Source Projects

Postgres Operator for Kubernetes: When Zalando opened up their Postgres operator for Kubernetes, it quickly saw improvements and adoption outside the company. "This code isn't a competitive advantage," explained Kay, "so it can only get better if more people work on it, adopt it, and harden it. Plus, upstream fixes benefit everyone."
Connexion: One of Zalando's popular Python projects, Connexion, had an external contributor serve as a maintainer for two years, demonstrating the effectiveness of their community-driven approach.
Fashion-MNIST: Zalando created Fashion-MNIST, a minced fashion dataset consisting of 60,000 training examples and 10,000 test examples. It's heavily used by the AI/ML/data science community as a benchmark to validate algorithms.
Patroni: Patroni enables high availability and automatic failover for PostgreSQL. "It has a lot of external contributors," said Kay. Zalando also contributes upstream to Postgres. "I think it's very important for us to not only make a mark, but make it rock solid so others can use and improve it. This benefits everyone because it's not just our two engineers who know it—it's a whole ecosystem."

Zalando: Fullfillment

Community Engagement

To set open source projects up for success, Zalando ensures the entire community can participate and grow projects. Pull request approvals are structured so external contributors receive internal approval from someone inside Zalando.

While encouraging upstream contributions, Zalando has a policy to not share confidential information and only sign whitelisted CLAs. For successful projects like Patroni where Zalando has significant commitment, "it's about really engaging with the open source community and getting traction. If we only had internal users and contributors, Patroni would probably be far less solid and used than it is now."

From speeding up internal processes to encouraging a culture of collaboration, Zalando leverages GitHub to continue moving the company forward and innovating within the broader open source community. "Open source is a nice way to leverage humankind potential," said Kay.