Show HN: Triplit – Open-source syncing database that runs on server and client

Original Article ↗ Hacker News Discussion ↗

Overview & Use Cases

  • Triplit is an open-source, syncing database that runs on both server and client with strong TypeScript, React, Svelte, and React Native support; Vue bindings are planned.
  • Targeted primarily at web developers and “classic” client–server apps with a central authoritative server rather than fully decentralized peers.
  • Reported real-world use includes offline-capable apps, user settings syncing across devices, and React Native apps; some users plan to move more critical data once HA deployments are available.

Sync Model & Conflict Resolution

  • Uses last-writer-wins (LWW) registers per attribute. Concurrent edits result in one winning; the other is still in history but not visible.
  • This is considered fine for simple fields (e.g., checkboxes), but not for collaborative text; richer collaborative editing via sequence/CRDT libraries is on the roadmap.

Architecture & Integrations

  • Server currently uses SQLite by default, with adapters also existing for LevelDB, LMDB, and file storage.
  • Not yet usable directly with existing Postgres or MongoDB; an internal Postgres sync tool (via replication/WAL2JSON) exists but isn’t production-ready.
  • Access control is defined via schema rules; a more granular system (separate read/insert/update/delete hooks) is in progress.

Performance, Latency & Schema Evolution

  • Sync latency is described as “fast enough” for most use cases but not tuned for sub-second cursor/metadata updates; a dedicated “presence API” is planned.
  • Query engine currently lacks aggregations (e.g., COUNT/UNIQUE); incremental/continuous aggregation is planned.
  • Schema evolution guidance: maintain backward-compatible schemas; tooling warns on breaking changes. Longer-term, lens-based migration approaches (Cambria-style) are being explored.

Comparisons to Other Tools

  • Positioned as a more batteries-included, relational-query alternative to tools like RxDB.
  • Other local-first / Postgres-centric solutions mentioned: ElectricSQL, PowerSync, Ably LiveSync, Evolu; Triplit differentiates by avoiding SQL and focusing on a language-level TS experience.
  • Comparisons are also drawn to Meteor’s pub/sub and optimistic UI model; some see Triplit as spiritually similar but more database-focused.

Licensing Debate (AGPL)

  • Triplit (including client libraries and bindings) is licensed under AGPL to keep it self-hostable and encourage contributions of modifications.
  • Extensive debate centers on AGPL’s “viral” nature: several commenters argue that using the AGPL frontend libraries would require entire frontends to be AGPL-compatible, making it unattractive for commercial products.
  • Others argue the legal boundaries (linking, derivative works) are ambiguous and thus risky; some suggest weaker copyleft (e.g., MPL) for client libraries.
  • The maintainers acknowledge confusion and intend to clarify their intent, but no concrete license change is stated.