--- title: Building LocalCents: A Local-first Expense Tracker with... description: A developer walks through building LocalCents, an educational side-project expense tracker using Automerge CRDTs for local-first sync, built as an... canonical: https://daily.dev/posts/building-localcents-a-local-first-expense-tracker-with-automerge-crdts-98fcddr48 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Building LocalCents: A Local-first Expense Tracker with Automerge CRDTs | daily.dev og:description: A developer walks through building LocalCents, an educational side-project expense tracker using Automerge CRDTs for local-first sync, built as an... og:url: https://daily.dev/posts/building-localcents-a-local-first-expense-tracker-with-automerge-crdts-98fcddr48 og:image: https://api.daily.dev/og/posts/98FCDDr48.png og:image:alt: Building LocalCents: A Local-first Expense Tracker with Automerge CRDTs og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Building LocalCents: A Local-first Expense Tracker with Automerge CRDTs **[ElixirStatus](https://daily.dev/sources/elixirstatus)** · 7 min read · 8 upvotes · 0 comments ## Summary A developer walks through building LocalCents, an educational side-project expense tracker using Automerge CRDTs for local-first sync, built as an Elixir/Phoenix app wrapped in Tauri for macOS, with Rustler bridging to Rust. The post covers conflict resolution via Lamport-clock-style operation IDs, a UI for surfacing sync conflicts to users (a notification bell and Conflicts tab), and handling deletion collisions. It closes with reflections on Automerge's access-control gaps (addressed by Ink & Switch's Keyhive project), Tauri's iOS CocoaPods dependency, using a GenServer architecture, Phoenix Storybook experience, and concerns about AI-assisted coding obscuring true understanding of Rust/Automerge internals. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How does Automerge resolve conflicting edits between offline peers? Automerge picks a deterministic winner using an operation_id, a pairing of a counter and actor id that functions as a Lamport clock. When two peers make conflicting edits offline, this ordering mechanism decides which edit wins once the peers reconnect and exchange changes, with deletions always taking precedence over edits. _Developers evaluating CRDT libraries can track how sync conflict resolution evolves by following local-first tooling on daily.dev._ ### What are the downsides of using Tauri for cross-platform desktop apps with iOS support? Tauri's iOS support still relies on CocoaPods, a dependency manager that has itself been marked deprecated, making it a notable red flag for teams wanting long-term iOS support. Native-feeling features like system-level context menus require using Tauri's specific tooling rather than generic web APIs, and CSS-based workarounds are used instead in simpler projects. _Teams weighing Tauri against other cross-platform frameworks can follow ecosystem changes like this on daily.dev before committing._ ### What is Keyhive and why does it matter for Automerge-based apps? Keyhive is a project from Ink & Switch aimed at adding access control capabilities to distributed CRDT tools like Automerge, an area that is otherwise hard to build into a peer-to-peer syncing system. It is considered still fairly bleeding-edge, addressing a real gap for anyone building multi-user local-first applications that need permissions. _Anyone building permissioned local-first apps can track projects like Keyhive maturing on daily.dev._ --- Tags: [#elixir](https://daily.dev/tags/elixir), [#tauri](https://daily.dev/tags/tauri), [#local-first](https://daily.dev/tags/local-first), [#crdt](https://daily.dev/tags/crdt) [View this post on daily.dev](https://daily.dev/posts/building-localcents-a-local-first-expense-tracker-with-automerge-crdts-98fcddr48) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Building LocalCents: A Local-first Expense Tracker with Automerge CRDTs","url":"https://daily.dev/posts/building-localcents-a-local-first-expense-tracker-with-automerge-crdts-98fcddr48","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/building-localcents-a-local-first-expense-tracker-with-automerge-crdts-98fcddr48"},"datePublished":"2026-08-31T19:55:32.277Z","dateModified":"2026-08-31T21:22:50.266Z","description":"A developer walks through building LocalCents, an educational side-project expense tracker using Automerge CRDTs for local-first sync, built as an...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/60a2bb372faad4fe3d29ca2e92c9b05e?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/60a2bb372faad4fe3d29ca2e92c9b05e?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"ElixirStatus","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"ElixirStatus","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/22e4640538124187827caf8cc8e39190","url":"https://daily.dev/sources/elixirstatus"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/building-localcents-a-local-first-expense-tracker-with-automerge-crdts-98fcddr48","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":8},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"elixir,tauri,local-first,crdt","timeRequired":"PT7M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"ElixirStatus","item":"https://daily.dev/sources/elixirstatus"},{"@type":"ListItem","position":3,"name":"Building LocalCents: A Local-first Expense Tracker with Automerge CRDTs"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/building-localcents-a-local-first-expense-tracker-with-automerge-crdts-98fcddr48#faq","mainEntity":[{"@type":"Question","name":"How does Automerge resolve conflicting edits between offline peers?","acceptedAnswer":{"@type":"Answer","text":"Automerge picks a deterministic winner using an operation_id, a pairing of a counter and actor id that functions as a Lamport clock. 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