Error Handler provides a custom interface to error handling in PHP. Several report formats can be used to reveal what circumstances led to a certain error. One for logging, one for display, and one for redirection. It captures the errors and captures (to a customized level) the context and variables surrounding the source of the error and neatly organizes them as a series of reports.
Fenris is a multipurpose tracer, debugger, and code analysis tool that detects and documents high-level language constructions, can recover symbols, graph program execution flow, detect internal functions, recover symbol tables, and deal with anti-debugging protection. It features a command-line interface as well as a SoftICE-alike GUI and Web frontend.
The Obcode (obfuscated code) library allows the programmer to perform arithmetic (e.g. data encryption and serial code generation) over abstract, parameterizable, and obfuscated data types using special high-level operators. The resulting low-level binary code doesn't reveal any real data directly and is if not very difficult, then at least very boring to reverse engineer and trace.
Hat (Haskell Tracer) is a tracing and debugging system for Haskell that can be used for comprehending working programs, and debugging an incorrect one. It consists of hat-trans, which transforms a program into one that traces itself using your normal compiler and a runtime library, and a set of browsing tools that explore the trace after execution of the program has completed.
Charles is a Web debugging tool, HTTP monitor, and reverse HTTP proxy for Web developers that includes plain text debugging of HTTPS/SSL. It is built in Java Swing, and runs on all Java platforms. It is an HTTP proxy server that displays requests and responses, complete with HTTP headers. This enables the developer to examine the exact content of HTTP exchanges, including cookies, caching, and redirects. It can also throttle your connection in order to simulate modem conditions. It is a valuable tool for all Web developers and is especially useful for debugging XML RCP, SOAP, Web services, AJAX/XMLHTTP, and Macromedia Flash client-server traffic including AMF, AMF 3, LoadVars, and XML Sockets.
Hardware Debugger is a graphical tool for detecting, diagnosing, and testing custom hardware. It is designed to meet the needs of the hardware developer by enabling quick and easy testing of hardware without writing any code. Hardware Debugger runs under Linux, Solaris, and Windows.
Zoidberg (a.k.a. zoid) provides a modular Perl shell written, configured, and operated entirely in Perl. It aspires to be a fully operational login shell with all the features one normally expects. But it also gives direct access to Perl objects and data structures from the command line, and allows you to run Perl code within the scope of your command line.