Journler is an open-source hybrid diary and personal information manager for Macintosh. It features a three-pane interface and supports tagging and categorizing of entries. The entries can be rich text, but also can contain images, PDFs, and other media that OS X supports. It is oriented toward chronological organization of entries, as in a diary or journal, and has a built-in calendar. Later versions aimed to be a flexible tool for personal project management and for fans of the Getting Things Done system.
Like many recent OS X applications, Journler supports smart folders that can automatically update themselves based on some user-delimited criteria. Journler allows nesting of folders, including smart folders, under one another, which is more unusual. Its support for easy creation of hyperlinks between entries, with automatic backlinks, allows it to be used as a personal wiki.
Journler was originally created by Philip Dow to meet his own needs. In September 2009, Dow announced he would cease development on Journler. In February 2011, it was announced that Journler would be open sourced. The source code is currently hosted on GitHub.
In August 2015, Journler's creator wrote an article citing Howard Rheingold's 1985 book Tools for Thought and John Markoff's 2005 book What the Dormouse Said, and explaining how he has come to understand Journler as a "tool for thought" in a tradition of computer-assisted intelligence augmentation dating back to computer science pioneers Vannevar Bush, J. C. R. Licklider, and Douglas Engelbart.