ClickHouse deserves a better SQL client.

Query and edit ClickHouse, MySQL/MariaDB, PostgreSQL and SQLite in one app. Copy tables between engines in one dialog. The keys you know from HeidiSQL work here too.

Download for Windows See pricing

Also for LinuxmacOS

TRIAL-TBD, then PRICE-TBD per user per year.

Crop of the ZephyrQL Table tab for the ClickHouse table uk_price_paid: column types such as UUID, Enum8 and LowCardinality(String), the sorting key, the MergeTree engine, 974,087 rows and the CREATE TABLE statement. — Table tab, ClickHouse 26.5, Windows 11. Full window

Copy a table to another engine. Read the SQL first.

Pick the tables, the target session and a mode: Create, Append, Truncate or Recreate. Before anything runs, the preview shows the type of every column on both sides and the CREATE TABLE statement. Copy whole tables, filtered tables or a query result.

The ZephyrQL Transfer dialog copying the PostgreSQL table customer to ClickHouse: a column list maps integer to Int32, text to String, boolean to Bool and timestamp with time zone to Nullable(DateTime64(6, 'UTC')), with the generated CREATE TABLE statement below. — Transfer preview, PostgreSQL 17 (pagila sample database) to ClickHouse 26.5, Windows 11.

Give your AI agent read-only access to a database.

ZephyrQL runs an MCP server, so Claude Code, Cursor and other MCP clients can list your connections, read schemas and run queries. Access is off until you turn it on for a connection. Read only is enforced by the server: readonly=1 on ClickHouse, a read-only transaction on PostgreSQL and MySQL, a read-only file on SQLite. The agent never gets your password.

Level	The agent can
Off (default)	Nothing. The connection is not listed.
Read only	SELECT, SHOW, DESCRIBE, EXPLAIN and other reads
Read & write data	Also INSERT, UPDATE and DELETE. No DDL. ClickHouse allows INSERT only.
Full	Any single statement your database user may run

Level

The agent can

Off (default)

Nothing. The connection is not listed.

Read only

SELECT, SHOW, DESCRIBE, EXPLAIN and other reads

Read & write data

Also INSERT, UPDATE and DELETE. No DDL. ClickHouse allows INSERT only.

Full

Any single statement your database user may run

Read only limits what the agent can change. The rows it reads still go to your AI provider.

The ZephyrQL session manager with the AI access tab open for a ClickHouse connection. The Access list offers Off, Read only, Read and write data, and Full (including DDL); Off is selected. — Session manager, AI access per connection, Windows 11.

Edit rows in the grid, also without a primary key.

A paged grid with a WHERE filter and server-side sort. Edit cells, insert and delete rows, set NULL or DEFAULT, then post. If a key would match more than one row, ZephyrQL stops and tells you. Values go to the server as parameters, and the SQL log shows every statement with its duration.

ZephyrQL on Windows 11: the database tree on the left, the Data tab of the ClickHouse table uk_price_paid in an editable grid, and the SQL log pane at the bottom that lists each statement with its time and duration. — Data tab, ClickHouse 26.5.4.21, uk_price_paid: HM Land Registry Price Paid Data 2025 without the address fields, 974,087 rows. Contains HM Land Registry data © Crown copyright and database right 2021, licensed under the Open Government Licence v3.0. ZephyrQL build 62fd274.

Also in the box

Query editor: Highlighting per engine, completion of tables and alias-aware columns, run all or the current statement, one result tab per result set, history. Tabs come back after a restart.
ClickHouse table view: Engine, sorting key, partition key, sizes and the CREATE statement. Lightweight UPDATE and DELETE on MergeTree tables.
Sessions: Folders, colors and notes per connection. TLS with a CA file and a client certificate.
Passwords: Kept in memory. On Windows you can save one per profile, encrypted for your Windows account.
Import and export: SQL dumps, CSV import, grid export.
Coming from HeidiSQL: Same layout and main keys: F9 runs your SQL, F5 refreshes, Ctrl+T opens a query tab. ZephyrQL adds ClickHouse and AI access. All shortcuts

One license. Every engine and every feature.

One license per user per year covers all of it. TRIAL-TBD. VAT-TBD.

Not supported yet: SSH tunnels, SQL Server and Firebird. Check that your setup works during the trial.

PRICE-TBD per user per year

ClickHouse, MySQL, MariaDB, PostgreSQL and SQLite
Table copy between engines
MCP server for AI agents
All updates during the license year

Download ZephyrQL

Questions before you buy

Does it work like HeidiSQL?: The layout, the tabs and the main keys follow HeidiSQL. The code is our own; ZephyrQL is not affiliated with HeidiSQL.
What can an AI agent do with my data?: Nothing until you turn on AI access for a connection. Then it can read, unless you allow more for that connection. What it reads goes to the AI provider you use.
Which operating systems does it run on?: Windows. Linux and macOS builds are a preview and are untested.
What is missing?: SSH tunnels, SQL Server and Firebird.
Who makes ZephyrQL?: SELLER-TBD. Support: support@zephyrql.com.

Try ZephyrQL on your own database.

TRIAL-TBD, then PRICE-TBD per user per year.

Download ZephyrQL