Harlequin

Harlequin is an open-source SQL IDE that runs in the terminal and connects to many databases through adapters.

Harlequin is a Python SQL IDE for the terminal. The recommended install is as a uv tool, which puts it on the PATH in its own environment; pip, pipx, Poetry and a community Homebrew formula are also documented. Database support comes from adapter plugins installed into the same environment, including extras such as Postgres, with MySQL/MariaDB and ODBC listed on the Homebrew formula. Adapter docs list packages from the maintainers and from the community. Full documentation is at harlequin.sh. It needs Python 3.9 or newer.

Harlequin at a glance

Best for: Software engineer
Runs on: CLI, open source, Linux, macOS, Windows
Pricing: Free and open source
Released: May 2023
Category: AI coding tool
Website: harlequin.sh

Key features

Terminal SQL IDE with a keyboard-driven UI
Install as a uv tool, or via pip, pipx or Poetry
Adapter plugins for many databases
Postgres extra and other community adapters
Community Homebrew formula with several adapters
Docs at harlequin.sh

Use it for

Write and run SQL against a local DuckDB file
Connect a terminal session to Postgres
Keep a SQL editor when no GUI is available

Alternatives to Harlequin

Tabularis — Combines a full-featured human SQL editor with a built-in Model Context Protocol server.
Postquel — Uses your existing local Claude Code, Codex, or Cursor AI account.
Frizky Kramer — Integrates with existing Claude Code, Codex, or Cursor installations.
NabuSQL — Fast lightweight database manager with a 9 MB installer and no subscription.
Dolt — Provides version control features for relational database management.
DBX — It combines lightweight size, open-source access, and built-in AI for over one hundred databases.
Hazzel — Brings inspectable safety mechanisms, local model support, and zero subscriptions.
OpenCode — Works with 75+ model providers, local models, and existing subscriptions
LLMSchema — Provides AI coding agents with accurate database schemas without context bloat.
DBCode — It brings a full database IDE directly into code editors without separate apps.
Cline — Open source, any model, with approval on every step
OpenClaude — Connects one terminal interface to over 200 different AI models.

All Harlequin alternatives