SciTE is an extendable development environment for producing source code and markup language files. Your preferred tools can be integrated into SciTE.
SciTE is customised through editing text files containing a list of properties in order to allow control with flexibility.
Available for 12 years on Windows and Linux, SciTE has now been implemented for OS X.
Documentation in OS X Help Viewer format is included with SciTE and shared documentation with other implementations can be viewed here.
SciTE may be purchased from the Mac App Store.