Visual JSON - Visual JSON is a simple and very easy to use JSON visulization tool for JSON API server/client developers.
Validator S.A.C. - Validator S.A.C. (Stand Alone Complex) is a stand-alone, easy to install, version of the W3C's HTML/XHTML Markup Validator for Mac OS X. Validator S.A.C. is a normal Mac OS X application.
Cocoa JSON Editor - Powerful tool for developers that use JSON as a data exchange format. Create, import and edit JSON data.
Power JSON Editor - Power JSON Editor is a powerful JSON editor for developers. By Power JSON Editor, developers can easily import JSON data from web, or import plist data as JSON, and also can export JSON to plist file.
Open Validator - 1) Verification of a single page or entire web site at your option;2) HTML Validation against W3C DTDs and WHATWG (X)HTML5 pre-release schemas;3) Automatic checking and correction of many aspects of c
Total Validator Tool for OSX - Why use separate validation tools to check your web pages when you only need one? Total Validator performs the most important checks on your web pages through a simple to use interface.