FLEX vs OllyDbg

FLEX is a free, open-source debugging and exploration library for iOS applications. It runs inside the app and places a toolbar in a window above it, allowing developers to inspect and change application state without an LLDB or Xcode connection or a remote debugging server. The tool can inspect view hierarchies, find live heap objects, show and modify properties and ivars, and call methods. Its network history covers NSURLConnection and NSURLSession requests with timing, headers, and responses. Developers can browse app bundles and sandboxes, inspect SQLite and Realm databases, and view or edit NSUserDefaults values, including strings, numbers, arrays, and dictionaries. FLEX works in the iOS Simulator and on physical devices, supports Objective-C and Swift, and requires an iOS 9-or-later target. Installation options include CocoaPods, Carthage, Buck, manual Xcode integration, and Swift Package Manager.

OllyDbg is a free 32-bit assembler-level debugger for Microsoft Windows, intended for binary analysis when source code is unavailable. It traces registers and identifies procedures, loops, API calls, switches, tables, constants, and strings. The debugger can load DLLs, attach to running programs, and handle multithreaded applications. Breakpoint types include conditional, logging, memory, and hardware breakpoints; execution tracing can log arguments for known functions. Patches can be retained between sessions, written back to executable files, and used to update fixups. An open architecture supports third-party plugins, and the maker provides a Plugin Development Kit with documented samples. Listed requirements include Windows 95, 98, NT 4.0, 2000, or higher; Win32s is unsupported. Development is frozen, and the 64-bit version is incomplete. Registration is free and requested for permanent or commercial use. The maker says original versions 1.00–1.10 do not communicate with other computers except for remote files specified by the user.