HeidiSQL allows exporting any MySQL database in JSON format. Read more…
Highlight any data in the DATA tab, or in the query result set… then right click and select Export Grid Rows option.
This option then allows you can export any of your data as JSON, straight into clipboard or directly to file:
Other options are outlined in this post: http://stackoverflow.com/questions/5036605/how-to-export-a-mysql-database-to-json, it also include the one above, which I added into this thread.