# How Notion Rebuilt Its Block Engine for Hybrid Local-Sync

Page: https://stenobird.com/podcast/the-cto-podcast-with-fexingo-technical-leadership-architecture-and-engineering-org-7871807/how-notion-rebuilt-its-block-engine-for-hybrid-local-sync
Text version: https://stenobird.com/podcast/the-cto-podcast-with-fexingo-technical-leadership-architecture-and-engineering-org-7871807/how-notion-rebuilt-its-block-engine-for-hybrid-local-sync.md
Podcast: [The CTO Podcast with Fexingo: Technical Leadership, Architecture, and Engineering Org](https://stenobird.com/podcast/the-cto-podcast-with-fexingo-technical-leadership-architecture-and-engineering-org-7871807)
Published: 2026-06-24T07:33:55+00:00
Episode link: https://audio.fexingo.com/business/the-cto-podcast/episode-0070.mp3
Audio file: https://audio.fexingo.com/business/the-cto-podcast/episode-0070.mp3
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Duration seconds: 366

## Resource

Notion's block-level architecture was designed for single-user documents. But as the product scaled to 100 million users, real-time collaboration exposed deep cracks in its sync model. This episode unpacks how Notion's engineering team rebuilt its block engine from the ground up — migrating from a naive operational transform approach to a custom hybrid model that blends local-first performance with server-authoritative sync. We walk through the specific tradeoffs they made: why they ditched CRDTs for a timestamped delta approach, how they handled conflict resolution for nested blocks without locking, and the surprising lesson about battery life that shaped their sync cadence. If you're building a collaborative product or thinking about offline-first architecture, this episode has a concrete case you can reference. #Notion #BlockEngine #Collaboration #LocalFirst #SyncArchitecture #OperationalTransform #CRDT #ConflictResolution #OfflineFirst #EngineeringOrg #TechnicalLeadership #CTO #ProductivitySoftware #RealTimeSync #Architecture #FexingoBusiness #BusinessPodcast #BusinessAndTechnology Keep every episode free: buymeacoffee.com/fexingo

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