> Markdown version of [/videos/554-offline-first-automatic-data-synchronisations-for-your-web-and-mobile-applications?t=1292](https://www.wearedevelopers.com/videos/554-offline-first-automatic-data-synchronisations-for-your-web-and-mobile-applications?t=1292). Every page supports `.md` or `Accept: text/markdown`. Links point to the HTML versions so they work for humans too. Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md).

---

# Offline first & automatic data synchronisations for your web and mobile applications

Stop writing complex boilerplate for local caching and offline data collisions. AWS Amplify DataStore seamlessly automates real-time synchronization and conflict resolution for your web and mobile apps.

- **Speakers:** [Sebastien Stormacq](https://www.wearedevelopers.com/@sebastien-stormacq)
- **Event:** WeAreDevelopers LIVE
- **Published:** April 18, 2023
- **Duration:** 56:59
- **URL:** https://www.wearedevelopers.com/videos/554-offline-first-automatic-data-synchronisations-for-your-web-and-mobile-applications

## Summary

Modern users expect their mobile and web applications to function seamlessly regardless of poor networking conditions. However, building offline-first, real-time applications introduces heavy technical burdens for developers. Requirements typically include writing complex boilerplate for local caching, orchestrating real-time UI updates, and managing messy data collisions when multiple clients mutate data offline and then reconnect. Navigating the CAP Theorem's tradeoffs for mobile applications usually means prioritizing local data availability, which inevitably leads to significant data consistency challenges.

AWS Amplify DataStore provides a multi-platform local persistence framework that abstracts away these distributed system complexities. Instead of manually managing a local cache alongside network requests, developers interact exclusively with a standard DataStore API using native programming models (such as Swift, React, Android, or Flutter). Operations are performed against an on-device database, allowing immediate local updates, while a background synchronization engine transparently coordinates with a managed AppSync GraphQL backend via delta syncs the moment network connectivity returns.

Resolving data collisions is elegantly offloaded to server-side synchronization rules. By default, AWS AppSync utilizes an Auto Merge strategy that merges non-conflicting field updates seamlessly and applies a "last-writer-wins" logic for conflicting fields using version tracking. For more granular control, developers can opt for Optimistic Concurrency to reject outdated updates or trigger a custom AWS Lambda function for specialized business merging logic. By automating real-time subscriptions, conflict detection, and delta synchronization, Amplify DataStore allows developers to effortlessly deliver resilient native applications at scale.

**Keywords:** aws amplify datastore, offline-first applications, real-time data synchronization, graphql api management, aws appsync, conflict resolution strategies, optimistic concurrency, auto merge conflict resolution, local data persistence, cross-platform mobile development, delta sync resynchronization, cap theorem tradeoffs, nosql dynamodb integration, custom lambda merge logic

## Chapters

1. **Understanding offline first applications and the CAP theorem** (00:04) — Structuring mobile applications for disconnected environments prioritizes high availability over strict consistency for local data partitions.
1. **Real-time offline synchronization demo with AWS Amplify** (06:13) — A dual-client demonstration illustrates the real-time resolution of client-side local data entries after restoring network connectivity.
1. **Limitations of local memory caching for offline apps** (17:40) — Relying entirely on key-value memory caches restricts query complexity and exacerbates codebase fragility during state hydration processes.
1. **Simplifying offline data persistence using AWS Amplify DataStore** (21:32) — Leveraging native persistence frameworks seamlessly unifies local storage models with remote asynchronous updates to cloud endpoints.
1. **Strategies for data conflict detection and automated resolution** (28:46) — Implementing monotonic versioning counters and timestamp markers establishes reliable baseline rules for executing concurrent metadata merges.
1. **Optimizing database resynchronization payloads utilizing delta sync** (36:51) — Delta synchronization operations target backend log tables to selectively pull only required modification differences instead of full database states.
1. **Framework compatibility and developer evangelism career track Q&A** (39:38) — Reviewing platform compatibility details before transitioning into a discussion surrounding technology advocacy and cloud engineering career trajectories.

## Related Moments

- [Architecting web applications for seamless offline availability](https://www.wearedevelopers.com/videos/45-progressive-web-apps-the-next-big-thing) (from "Progressive Web Apps - The next big thing")
- [Architectural overview and offline data flow](https://www.wearedevelopers.com/videos/694-build-delightful-mobile-experiences-with-kotlin-realm-and-atlas-device-sync) (from "Build Delightful Mobile Experiences with Kotlin, Realm, and Atlas Device Sync")
- [Achieving application reliability and offline accessibility](https://www.wearedevelopers.com/videos/289-pwas-in-2021) (from "PWAs in 2021")
- [Modern application stacks and real-time data requirements](https://www.wearedevelopers.com/videos/806-leveraging-real-time-data-in-fsis) (from "Leveraging Real time data in FSIs")
- [The historical struggles of building persistent progressive web apps](https://www.wearedevelopers.com/videos/1730-wearedevelopers-live-accessibility-isn-t-magic-longevity-devrel-in-times-of-ai-and-more) (from "WeAreDevelopers LIVE - Accessibility isn't magic, Longevity, Devrel in times of AI and more")
- [Building local first data synchronization across transport meshes](https://www.wearedevelopers.com/videos/1148-you-are-not-an-ai-developer) (from "You are not an AI developer")

## Related Articles

- [Making Data Warehouses Fast: A Developer’s Story](https://www.wearedevelopers.com/magazine/107-making-data-warehouses-fast-a-developer-s-story)
- [Dev Digest 139 - Soft and hard queries](https://www.wearedevelopers.com/magazine/487-dev-digest-139-soft-and-hard-queries)
- [Dev Digest 132 - Binging WADFlix?](https://www.wearedevelopers.com/magazine/473-dev-digest-132-binging-wadflix)
- [Dev Digest 120 - Apple and peers](https://www.wearedevelopers.com/magazine/455-dev-digest-120-apple-and-peers)

## Related Jobs

- [Senior Software Engineer, Client Apps Platform](https://www.wearedevelopers.com/jobs/ext/1773893-senior-software-engineer-client-apps-platform) at **GitHub**
- [Founding Mobile Engineer (iOS)](https://www.wearedevelopers.com/jobs/ext/1648532-founding-mobile-engineer-ios) at **Almedia**
- [Software Engineer L3](https://www.wearedevelopers.com/jobs/ext/1840587-software-engineer-l3) at **Twilio**
- [Senior Software Engineer (L3)](https://www.wearedevelopers.com/jobs/ext/1956800-senior-software-engineer-l3) at **Twilio**
- [Remote Senior Software Engineer](https://www.wearedevelopers.com/jobs/ext/646379-remote-senior-software-engineer) at **Twilio**
- [Staff Software Engineer (L4)](https://www.wearedevelopers.com/jobs/ext/591818-staff-software-engineer-l4) at **Twilio**