You can search and install JOSM plugins from the Presets > Preset preferences menu. After installing a plugin, you’ll need to restart the JOSM editor. Try for yourself and search for plugins that help you map what you’re interested in most.
Occasionally, you may need to undo a changeset you’ve uploaded by mistake to OpenStreetMap. The Reverter plugin removes any accidental changes you’ve uploaded that could affect the quality of OpenStreetMap.
After installing the plugin, open it from the Data menu by selecting Revert changeset.
The plugin allows for easy reverting of the full or partial changeset or restores deleted objects. To revert: enter your Changeset id, select what you want to revert, and click revert.
With Geochat, you can communicate with other OpenStreetMap editors working near you. Chatting is handy for collaboration and to avoid conflicts when mapping in the same area.
Install the plugin and activate it in the Windows on the JOSM menu by selecting Geochat.
Right-clicking on the plugin interface gives you the option to Show users on map near you, and the option to chat with them either in public or private.
Todo list plugin
The Todo list plugin maintains a list of OpenStreetMap features for review. For example, if you want to check classifications on all roads in an area, you can build a review list with Todo. This way you will never miss anything that you want to validate.
Install the plugin and activate it in the Windows on the JOSM menu by selecting Todo List.
You can select all the roads in an area with a filter.
Add these roads to the todo list with the add button. After validating a road, click the mark button to clear the task from the list or skip button to move on to the next task.
These are many JOSM plugins that will come in handy when contributing data to OpenStreetMap. A full listing of other plugins is available in the OpenStreetMap Plugin wiki. Tweet at me with your favorite plugin tips.