Please note that SQL Workbench/J has no relation to the product MySQL Workbench which is maintained and owned by Oracle.
If you are looking for MySQL Workbench support please contact Oracle.

Prerequisites

SQL Workbench/J needs a Java runtime (it also works with a JDK - "Java Development Kit").

Binaries for Windows, Linux or MacOS can be downloaded for free from Adoptium, OpenJDK or Azul Systems.
You have to install Java 11 or higher to run SQL Workbench/J.
Using a 64bit Java runtime is highly recommended.

The ZIP archive contains a batch file/shell script ("download_jre.cmd" or "download_jre.sh") that can automatically download the needed Java runtime, so you don't have to download the Java runtime in advance. After unpacking the archive, run the download_jre script and it will download and extract an appropriate Java runtime to the folder where the batch file is located. The Windows launcher and shell scripts will automatically use that Java runtime.

Installation

After downloading SQL Workbench/J, unzip the archive into a directory of your choice.

The application is now ready to be run, no further installation steps are necessary.

More details about installing and configuring the application can be found in the manual

Starting the application

Microsoft Windows

If you are using Microsoft Windows® start the application by double-clicking the SQLWorkbench64.exe executable. If you are a 32bit Java runtime (which is not recommended), use SQLWorkbench.exe instead.

Linux and other Unix-style operating systems

If you are running Linux (or another Unix® like operating system) you can use the supplied shell script sqlworkbench.sh to start the application.

Configuring the database (JDBC) drivers

When starting SQL Workbench/J for the first time, you will need to configure the JDBC drivers for your database system.

When the initial connection dialog is displayed ("Select Connection Profile"), click on the "Manage Drivers" button to specify the location of the driver's JAR file(s).

The necessary JDBC driver is not part of the SQL Workbench/J distribution and if you have not already downloaded one you will need to do that before you can connect to the database.

Links to the download locations for several popular database systems are available here

To define the driver, select the JAR file(s) that is supplied by your database system. The driver definition dialog has a list of pre-defined drivers and the name of their jar file.

To select the driver's JAR file, click on the "..." button next to the input field labelled "Library". After you have selected the JAR file, SQL Workbench/J will search for the approriate driver class to be used. If a JDBC driver implementation is found in the JAR file(s), it is automatically entered in the input field labeled "Classname". If more than one class is found you will have to select one. Please consult the manual of your driver (or database) for details on which driver class to use then.

Specifying the database connection

If you have specified the driver's location, you can close the "Manage drivers" dialog. In the "Select Connection Profile" dialog, you have to specify the details for your database connection. You can find more details on how to define the JDBC driver in the manual.

To setup the connection to your database, select the JDBC driver from the dropdown, then fill out the JDBC connection URL (a sample URL has been inserted into the input field) and most importantly: the username and password. Click OK to connect to the database.

For further details, please refer to the manual