A modern, lightweight, multi-engine database client — an open-source alternative in the spirit of Navicat.

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Quaero (Latin quaero, "I seek / I inquire") is a multi-engine database client with a C core (libdbcore) and a web UI running on the OS-native webview (WebView2 on Windows, WebKitGTK on Linux, WKWebView on macOS). A modern UI without the weight of Electron, and a native engine that talks directly to each database's client libraries.

Supported engines

Engine	Status
SQLite	✅ Complete (verified)
PostgreSQL	✅ Via libpq — SSL/TLS, SCRAM
MySQL / MariaDB	✅ Complete (verified) — SSL/TLS, SSH tunnel
Informix	✅ Via ODBC (x86 build)
MongoDB	✅ Read (find/aggregate, mongosh syntax)
SQL Server, Oracle	⏳ Planned (M12)

Engines load as plugins (.dll/.so) implementing a C contract: adding an engine never touches the core. See how to write a driver.

Features

SQL editor

• CodeMirror editor with schema-aware autocomplete, SQL formatting, and run selection / statement / document.
• Query history with per-query duration and slow-query marks.
• Snippets / favorites; command palette (Ctrl/Cmd+K).
• Visual execution plan (EXPLAIN) as a tree.

Result grid

• Virtualized, per-column sort and filter, real pagination (offset).
• Inline transactional editing (insert/update/delete + SQL preview + commit/rollback); row detail (form view).
• Export CSV / JSON / SQL / XML / HTML / XLSX; import CSV / JSON / XLSX.
• Charts (bar / line / pie).

Objects and design

• Lazy, virtualized object tree grouped by type (tables, views, procedures, functions, triggers, events).
• Table designer (create and ALTER), index and constraint editor.
• Procedures / functions, triggers / events, users and privileges.
• Server monitor (process list + kill), slow queries.
• ER diagram (real foreign keys from the engine) and a visual query builder.

Data across connections

• Schema and data sync, table transfer between connections, and test data generation.

Connectivity and platform

• SSH tunnel (all engines), SSL/TLS (MySQL, PostgreSQL), and import/export of saved connections.
• Light/dark theme with the indigo brand, Settings and About panels, keyboard shortcuts, adaptive context menus.
• Single executable (embedded UI) + drivers as plugins. No Electron.

Install

Windows: download the latest .msi installer from Releases and run it. Requires the WebView2 runtime (already bundled in Windows 11). Every release attaches a SHA256SUMS.txt to verify the download: sha256sum -c SHA256SUMS.txt (or CertUtil -hashfile quaero-*.msi SHA256).

Linux (AppImage/deb) and macOS (.app) are coming in future releases.

Build from source

Requirements: CMake ≥ 3.20, a C11 compiler (GCC/Clang/MSVC) and, recommended, Ninja; Node + pnpm for the UI.

# UI (produces frontend/dist/index.html, a single file that gets embedded)
pnpm --dir frontend install
pnpm --dir frontend build

# Core + app
cmake -S . -B build -G Ninja
cmake --build build
ctest --test-dir build --output-on-failure   # core tests

The binary lands in build/app/quaero (.exe on Windows). Webview dependencies: Linux libgtk-4-dev libwebkitgtk-6.0-dev; macOS system WebKit; Windows WebView2 (downloaded at build time). Core only: -DQUAERO_BUILD_APP=OFF.

PostgreSQL: the driver links libpq. On x64 it uses a system libpq; the x86 release build compiles a static libpq from source with -DQUAERO_LIBPQ=ON.

MongoDB: the driver links libmongoc. Without a system copy, build it from source with -DQUAERO_MONGOC=ON (fetches and statically links mongo-c-driver; TLS via Secure Channel on Windows).

Windows MSI installer: see installer/build-msi.sh (WiX v5 via dotnet tool). Releases are cut automatically on a version tag — see docs/VERSIONING.md.

Per-engine smoke: scripts/smoke/run.sh <sqlite|mysql|mongodb> — see docs/QA-SMOKE.md.

Architecture

Frontend (OS webview)  ──JSON IPC──>  C core (libdbcore)  ──vtable──>  Drivers (plugins)
   SolidJS UI, virtual grid,           connection, queries,             sqlite, postgres,
   SQL editor, tools                   introspection, editing, tx       mysql, informix, mongodb, …

Details in docs/ARCHITECTURE.md.

Documentation

• ROADMAP · Architecture
• Driver contract · How to write a driver
• IPC protocol · Shortcuts · Versioning
• Verification matrix · Brand
• Contributing

License

GPLv3. Proprietary-engine drivers ship as separate plugins, loaded at runtime, to respect their licenses. Full third-party inventory in THIRD-PARTY.md.