RxDB vs SQLDelight

RxDB is a NoSQL database for JavaScript that runs inside an application and keeps data locally on the client. It supports offline operation, including applications that run entirely without a backend. When synchronization is needed, its Sync Engine connects to backends including RxServer, GraphQL, Firebase, Supabase, MongoDB, NATS, HTTP, CouchDB, WebRTC, Appwrite, Google Drive, and Microsoft OneDrive. Observable queries update as stored data changes. RxDB runs in browsers, mobile apps, desktop applications, and servers, with storage options including LocalStorage, IndexedDB, OPFS, SQLite, Node.js Filesystem, Expo Filesystem, MongoDB, and FoundationDB, among others. Collections use JSON Schema with validation and migration support. An encryption plugin protects locally stored documents with a password in browsers, React Native, and Node.js. The free tier is under Apache 2.0 and allows up to 13 open collections in parallel. Free users get community support through GitHub and Discord; Enterprise includes an SLA with a 24-hour first response. Pro costs $99 a month billed annually, and Pro Plus costs $239 a month billed annually.

SQLDelight generates typesafe Kotlin APIs from SQL statements and checks database schemas, SQL statements, and migrations at compile time. Its IDE features include SQL autocomplete and refactoring support. Documented database dialects include SQLite, MySQL, and PostgreSQL; HSQL and H2 are experimental, while CockroachDB, DB2, and Oracle dialects are listed as third-party options. The JVM connection overview lists MySQL and PostgreSQL, with JDBC and R2DBC variants shown for supported dialects. The project provides a Gradle plugin and extensions for Kotlin coroutines, RxJava, and AndroidX Paging. Its coroutines extension can expose a query as a Flow and emit updated results when the queried data changes. The Gradle verifySqlDelightMigration task applies migrations to stored schema databases and checks whether they reach the latest schema. SQLDelight is open source under the Apache-2.0 license and has a free listing at free, with no paid tiers stated. Its listed platforms are Android, API, iOS, Linux, macOS, web, and Windows.