Scratchpad provides an environment to experiment with JavaScript in Firefox. The item on the browser's Tools menu opens one or more separate windows which allow writing and running code that interacts with the active tab in the topmost window, in either the normal page context or Scratchpad's content context for the tab (with some limits) or in Scratchpad's background context. Scratchpad uses CodeMirror 5, Copyright © Marijn Haverbeke and others. CodeMirror is released under the MIT License.