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Pellet Reasoner Plug-in for Protégé 4

Protégé is the leading OWL ontology development environment for both commercial and academic uses. The Pellet Reasoner Plug-in, version 1.0, makes Pellet 2 available in Protégé 4, including Pellet’s unique capabilities: datatype reasoning, SWRL support, etc. (In a future release of the plug-in, Pellet’s incremental classification feature will also be available.)

Commercial Development & Support

Clark & Parsia LLC provides custom development and support for both Pellet 2 and Protégé (versions 3 and 4); please get in touch with us if your organization needs on-demand support for or customization of these tools.

Pellet Reasoner Plug-in License

Use of Pellet 2 in Protégé via the Pellet Reasoner Plug-in is according to the terms of Pellet’s license. In short, Pellet is available either under the terms of the free software license, AGPL v. 3 license, the full text of which is available, or Pellet may be licensed for use in commercial or proprietary products by contacting Clark & Parsia.


The Pellet Reasoner Plug-in is distributed via the auto-update feature of Protégé 4. To install, follow these steps:

  1. Select “File | Preferences”.
  2. Select “Plugins” tab.
  3. Click the “Check for downloads now” button under the “Plugin registry” heading.
  4. Scroll down the “Downloads” list to find “Pellet Reasoner Plug-in” and select the checkbox next to it (See the screen shot below).
  5. If you agree with the licensing terms click “Install”.
  6. When you see the “Updates will take effect next time Protege starts” message, restart Protégé.


Environments with restrictive firewalls may prevent the automatic auto-update from connecting to our website to download the plugin. In such a case, follow these steps for manual installation:

  1. Download the plugin from the website using your web browser: Plugin for Protégé 4.0 , Plugin for Protégé 4.1 alpha – before build 209 , Plugin for Protégé 4.1 beta – build 209 and later
  2. Copy the downloaded file (com.clarkparsia.protege.plugin.pellet.jar) to the “plugins” directory inside of your Protégé installation.
  3. Restart Protégé