(Based on analysis of Apache Incubator case studies)

Incubation at the Apache Software Foundation follows many routes. Projects join with different histories, community sizes, and goals. The case studies show that success is not defined by speed but by alignment with ASF values such as openness, transparency, and community-led governance. The following paths summarise what has been observed across multiple projects.

1. Established Community, Short Stay

Projects that arrive with diverse contributors, active user adoption, and an ASF-compatible release process often graduate within a year. Incubation mainly serves to verify governance, licensing, and branding alignment.

Typical characteristics

• Multi-organisation contributor base before entry
• Regular releases already underway
• Mailing list and vote culture adopted quickly

Examples reflected in the data
Projects such as Flink, Iceberg and Arrow followed this route, entering with clear community structures and graduating soon after alignment work was complete.

2. Typical ASF Path (1–2 Years)

This is the most common route. Projects start with a small but functional team, expand participation through ASF processes, and graduate once releases, governance, and diversity are stable. Progress is steady rather than fast, balancing learning and autonomy.

Typical characteristics

• Initial core team with moderate external engagement

• Public development and voting culture established within months

• One or two releases per year after early setup

• Mentors active but not dominant in decision-making

Examples
Druid, Pulsar and APISIX show this pattern: consistent progress, gradual growth, and sustainable graduation after about two years.

3. Emerging Community, Steady Growth

Many projects begin with a small founding team and use incubation to grow broader participation. Progress is measured in new committers, public discussions, and reliable releases rather than speed.

Typical characteristics

• Small but motivated initial team
• Focus on attracting external contributors
• First Apache releases developed during incubation

Examples reflected in the data
Pinot, Airflow and Kafka showed this pattern with slow early progress followed by strong, sustainable communities.

4. Complex Migration or Long-Term Incubation

Large or long-running codebases can require extensive IP clearance, infrastructure migration, or dependency review. These projects may take several years but often become strong ASF communities once established.

Typical characteristics

• Complex or legacy code needing review
• Gradual transition of infrastructure and documentation
• Extended mentor and IPMC involvement

Examples reflected in the data
NetBeans and IoTDB illustrate this path, where the technical migration was the dominant timeline factor.

5. Withdrawal or Completion Outside Apache

Some communities determine that the ASF structure does not align with their preferred workflow or governance model. Withdrawal is a transparent conclusion that leaves both the project and the ASF in a clear position.

Typical characteristics

• Existing governance or branding constraints outside ASF
• Low on-list activity or preference for external channels
• Community consensus to withdraw

Examples reflected in the data
Zipkin chose this outcome after maintaining active development outside the ASF structure.

6. Graduation Followed by Quieter Activity

A small number of projects graduate successfully but later slow down or retire. This reflects the normal lifecycle of open-source technology as interests and ecosystems evolve.

Typical characteristics

• Healthy governance and releases at graduation
• Gradual reduction in contributor activity post-graduation
• Eventual move to the Apache Attic if activity ceases

Examples reflected in the data
Projects such as Mesos, Trafodion, and MXNet followed this trajectory, each contributing valuable lessons in community lifecycle and sustainability.

7. Extended Stewardship and Mentor Continuity

Some long-running incubations benefited from mentors who stayed engaged throughout, ensuring stability and eventual handoff to independent governance.

Typical characteristics

• Mentors active for several years
• Regular status reviews and cultural alignment discussions
• Slow but steady progress toward autonomy

Examples reflected in the data
Projects such as Superset and ECharts demonstrate how consistent mentorship helped communities mature at their own pace.

Why These Paths Exist

Different incubation paths reflect the diversity of open-source projects that join the ASF. Some enter as mature software donations, others as small new communities, and some as large-scale migrations. ASF incubation is designed to accommodate all of these situations by focusing on community readiness and transparency rather than fixed timelines or metrics. The variety of outcomes demonstrates that incubation is flexible by design.

How to Use This Guide

• For podlings: to understand that progress varies with context. Duration alone does not reflect success.
• For mentors: to recognise different developmental paths and calibrate expectations accordingly.
• For observers: to see incubation as a process that adapts to community needs and fosters diversity across ASF projects.

Observations from the Case Studies

Across more than twenty examples, a few consistent themes appear:

• Most projects that graduate maintain regular release activity during incubation.
• Diversity of contributors often increases once discussion moves to ASF mailing lists.
• The time spent in incubation varies widely, with both short and long incubations leading to successful outcomes.
• Post-graduation activity levels change naturally over time as technology and community interests evolve.

These observations highlight that incubation outcomes depend on continued participation and transparency rather than project age, size, or sponsor.

Summary Table

Incubation is about building trust, transparency, and shared ownership. Each path adds to the ASF’s collective understanding of how diverse communities grow and sustain themselves in the open.