Zarr Summit 2025

October 13-17 • Rome, Italy
Unlocking Scalable and Accessible Open Science on the Cloud with Zarr
Zarr developer summit (October 13-17)Adopter days registration (October 16-17)
Zarr Developer Days (13-15): Technical deep-dives and feature development
Zarr Adopter Days (16-17): Bridge the gap - Zarr implementers and adopters collaborate

About the Summit

The Challenge

The transition from Zarr v2 to v3 has revealed fundamental coordination challenges. Progress has stalled on crucial technical consensus issues around variable chunk grids, sharding strategies, and codec standardization. Virtual meetings cannot provide the deep, real-time collaboration needed to resolve these complex technical disagreements.

The Solution

A week-long summit will transform months of asynchronous debate into days of productive problem-solving. Face-to-face collaboration will enable the trust-building and technical discussions necessary for a thriving open-source ecosystem, while connecting Zarr implementers directly with the adopters who depend on their work.

Two Connected Events

Developer Summit (Oct 13-15)

Who: Zarr Implementers

Focus: Technical deep-dives and breakthrough sessions

  • Variable chunk grid extensions
  • Sharding implementation
  • Codec standardization
  • Cross-language compatibility

Adopter Summit (Oct 16-17)

Who: People adopting Zarr

Focus: Collaboration and implementation guidance

  • Round-tables with implementers
  • Migration guidance for Zarr V3
  • Virtual Zarr for cloud-native access
  • Real-world adoption strategies

Why Zarr Implementers Should Stay for Both

See Your Work in Action

Experience how your technical implementations solve real-world problems for organizations like ESA, NASA, and leading research institutions.

Direct User Feedback

Get immediate input from large-scale adopters to shape future development priorities and ensure your work meets actual user needs.

Build Lasting Relationships

Strengthen connections with the user community that will sustain and guide the Zarr ecosystem's growth beyond this summit.

Registration Information

Full Summit (Developer + Adopter days)

Register by August 22

Dates: October 13-17, 2025

Includes: Breakfasts, Lunches, Travel support if needed

Ideal for: Zarr implementers and developers

Adopter Days Only

Register by September 12

Dates: October 16-17, 2025

Includes: Breakfasts, Lunches

Ideal for: Organizations evaluating or implementing Zarr