Looks interesting, was looking for something like this as currently for Flutter I use Loro via flutter_rust_bridge as the CRDT data store, but it's not SQL so some things like big queries are annoying. How are you handling CRDTs in a SQL database? I thought those were notoriously hard as relational wasn't built for CRDT style syncing?
This is cool. Reminds of Lotus Notes. In a strange way a concept that felt "outdated" is something that I would love to be the default behavior for many apps today.
It’s great to see apps being shipped with offline first (and flawless syncing as an optional feature) from ground up, sad to see many modern notes apps like notion or capacities treating offline as afterthought. But alas, it’s still a non trivial nut to crack.
Hope one day offline first will be a default and a solved problem.
Both use local SQLite and keep the backend authoritative. The main difference is that PowerSync mostly handles downstream replication and gives you an upload queue; your API still owns the write semantics. Syncular specifies the whole round trip. Durable commits, auth scopes, conflicts, replay, revocation and bootstrap.
Syncular also goes further up the stack: schemas plus SQL/SYQL generate typed queries for TS, Swift, Kotlin, Dart and Rust, and blobs, CRDT/encrypted columns and windowed sync are built into the protocol.
In my separate benchmark harness, Syncular currently does considerably better than the tested PowerSync setup. For example, 100k bootstrap is ~0.57s vs ~6.5s and offline replay ~35ms vs ~5.1s. Those are early results from one environment, though, not a universal claim (https://github.com/bkniffler/offline-sync-bench).
I've used PowerSync in the past with a huge initial bootstrap sync and was very frustrated by the performance back then (ca 1 year ago), which was one of the reasons to create my own library.
PowerSync is much more mature today obviously and still a great and proven tool.
Nice! Would recommend to decouple as much as possible and have tons of testing, every issue thats catched before having to go to the length of debugging client side issues is gonna save some sleep. Have been there, learned the hard way..
Yeah it was a deceptively complicated issue. I’m not sure if my implementation is as comprehensive, but it sounds similar: optimistic local writes, outbound queue, server as source of truth, each client has local SQLite.
The issue I found most difficult architecturally was how to deal with staying responsive on first sign in with a large DB. I ended up with a system I called “materialisation on demand” where it will search the server and download only those rows ahead of time.
EDIT: I also ended up using multiple local databases to ensure responsive writes during heavy synching activity.
Hi HN! I’ve been circling this problem for a long time.
In 2019 I built an offline-first datastore called debe. It used CRDTs and multi-master replication and never became something I could confidently ship. It did teach me that convergence is only a small part of sync. The difficult parts are durable writes, authorization changes, lost acknowledgements, schema upgrades, bounded bootstrap, and explaining what happened after something fails.
I eventually came back to the problem and built Syncular over the last year.
Every client has a real SQLite database: sqlite-wasm on OPFS in the browser and native SQLite elsewhere. Writes apply locally and enter a durable outbox in the same transaction. A server-authoritative commit log validates and orders them, using explicit scopes resolved inside the application backend.
The protocol is written down independently of the implementations. SSP2 is currently a draft, with canonical binary encoding and golden byte vectors. There are independent TypeScript and Rust client cores, both run against the same 95-scenario conformance catalog. The Rust core is exposed through Swift, Kotlin, Flutter, React Native, Tauri, Rust, and a small C API.
It also includes realtime WebSocket sync, resumable bootstrap segments, explicit conflict evidence, authorization revocation and local purge, windowed replicas, blobs, optional CRDT columns, per-column encryption, and typesafe generated queries for five languages.
Important boundaries: it is pre-1.0, self-hosted, and there is no managed service or peer-to-peer mode. Native packaging maturity still varies by ecosystem.
Let me know what you think, I'm happy about feedback!
There was a local-first conv just a few weeks ago in Berlin; if you're not yet part of that community I suggest reaching out. https://www.localfirst.fm/ for example, or https://lofi.so/
Looks interesting, was looking for something like this as currently for Flutter I use Loro via flutter_rust_bridge as the CRDT data store, but it's not SQL so some things like big queries are annoying. How are you handling CRDTs in a SQL database? I thought those were notoriously hard as relational wasn't built for CRDT style syncing?
I wish there was an established way to build local first software with a robust syncing in the background, either P2P or to a server.
I feel projects like this for local first and projects like Iroh for connectivity over NAT and through firewalls need to come together more.
It would be could to have a drop in framework for this.
Loro along with their protocol crate works great. Automerge has something similar.
It’s a bit weird to see every comment here talks about apps she or he has built but never really give a shit about this app itself.
This is cool. Reminds of Lotus Notes. In a strange way a concept that felt "outdated" is something that I would love to be the default behavior for many apps today.
It’s great to see apps being shipped with offline first (and flawless syncing as an optional feature) from ground up, sad to see many modern notes apps like notion or capacities treating offline as afterthought. But alas, it’s still a non trivial nut to crack.
Hope one day offline first will be a default and a solved problem.
In which way this is different from PowerSync?
Both use local SQLite and keep the backend authoritative. The main difference is that PowerSync mostly handles downstream replication and gives you an upload queue; your API still owns the write semantics. Syncular specifies the whole round trip. Durable commits, auth scopes, conflicts, replay, revocation and bootstrap. Syncular also goes further up the stack: schemas plus SQL/SYQL generate typed queries for TS, Swift, Kotlin, Dart and Rust, and blobs, CRDT/encrypted columns and windowed sync are built into the protocol.
In my separate benchmark harness, Syncular currently does considerably better than the tested PowerSync setup. For example, 100k bootstrap is ~0.57s vs ~6.5s and offline replay ~35ms vs ~5.1s. Those are early results from one environment, though, not a universal claim (https://github.com/bkniffler/offline-sync-bench).
I've used PowerSync in the past with a huge initial bootstrap sync and was very frustrated by the performance back then (ca 1 year ago), which was one of the reasons to create my own library.
PowerSync is much more mature today obviously and still a great and proven tool.
Interesting! I wrote something similar for my app recently, it was the first thing I coded using LLMs.
Nice! Would recommend to decouple as much as possible and have tons of testing, every issue thats catched before having to go to the length of debugging client side issues is gonna save some sleep. Have been there, learned the hard way..
Whats your app?
Yeah it was a deceptively complicated issue. I’m not sure if my implementation is as comprehensive, but it sounds similar: optimistic local writes, outbound queue, server as source of truth, each client has local SQLite.
The issue I found most difficult architecturally was how to deal with staying responsive on first sign in with a large DB. I ended up with a system I called “materialisation on demand” where it will search the server and download only those rows ahead of time.
EDIT: I also ended up using multiple local databases to ensure responsive writes during heavy synching activity.
The app is https://www.benko.app/ it’s available on iOS, android, Mac and windows.
Be warned, AI Slop ahead
Hi HN! I’ve been circling this problem for a long time.
In 2019 I built an offline-first datastore called debe. It used CRDTs and multi-master replication and never became something I could confidently ship. It did teach me that convergence is only a small part of sync. The difficult parts are durable writes, authorization changes, lost acknowledgements, schema upgrades, bounded bootstrap, and explaining what happened after something fails.
I eventually came back to the problem and built Syncular over the last year.
Every client has a real SQLite database: sqlite-wasm on OPFS in the browser and native SQLite elsewhere. Writes apply locally and enter a durable outbox in the same transaction. A server-authoritative commit log validates and orders them, using explicit scopes resolved inside the application backend.
The protocol is written down independently of the implementations. SSP2 is currently a draft, with canonical binary encoding and golden byte vectors. There are independent TypeScript and Rust client cores, both run against the same 95-scenario conformance catalog. The Rust core is exposed through Swift, Kotlin, Flutter, React Native, Tauri, Rust, and a small C API.
It also includes realtime WebSocket sync, resumable bootstrap segments, explicit conflict evidence, authorization revocation and local purge, windowed replicas, blobs, optional CRDT columns, per-column encryption, and typesafe generated queries for five languages. Important boundaries: it is pre-1.0, self-hosted, and there is no managed service or peer-to-peer mode. Native packaging maturity still varies by ecosystem.
Let me know what you think, I'm happy about feedback!
Demo: https://demo.syncular.dev Protocol: https://github.com/syncular/syncular/blob/main/docs/SPEC.md Background: https://syncular.dev/blog/offline-first-writes/ Docs: https://syncular.dev/
There was a local-first conv just a few weeks ago in Berlin; if you're not yet part of that community I suggest reaching out. https://www.localfirst.fm/ for example, or https://lofi.so/
Thanks for pointing me there! Posted to their discord, but seems not so active.