Sourcegraph for GitHub - Browse and search GitHub like an IDE
OpenGrok - OpenGrok is a fast and usable source code search and cross reference engine.
JSONView - Validate and view JSON documents.
GrepCode - GrepCode.com is a code search engine built by developers for developers to search and browse open...
JSON Viewer - The most beautiful and customizable JSON/JSONP highlighter that your eyes have ever seen.
Krugle - Krugle is the complete enterprise solution for search targeted to the development organization.