iaito is the official graphical interface for radare2, a libre reverse engineering framework. Based on radare2 and Qt-5/6. Iaito was the original name before being forked as Cutter. Use all your favourite r2 plugins and scripts (nothing is specific to iaito). Focus on simplicity, parity with commands, features, keybindings. Forensics, bindiffing, binary patching... not just a static disassembler.
r2 is a complete rewrite of radare. It provides a set of libraries, tools and plugins to ease reverse engineering tasks. Distributed mostly under LGPLv3, each plugin can have different licenses (see r2 -L, rasm2 -L, ...).
The radare project started as a simple command-line hexadecimal editor focused on forensics. Today, r2 is a featureful low-level command-line tool with support for scripting with the embedded Javascript interpreter or via r2pipe.
r2 can edit files on local hard drives, view kernel memory, and debug programs locally or via a remote gdb/windbg servers. r2's wide architecture support allows you to analyze, emulate, debug, modify, and disassemble any binary.
YARC (Yet Another REST Client) is an easy-to-use REST Client. Use it to develop, test and debug RESTful APIs. Save favorite requests (including headers, payload etc.) and re-use them with the click of a button. Import/Export favorites. Your favorites are automatically synced with your Google account and are not tied to a single machine. View and re-run all your previous requests and responses.
I use it with Vivaldi, and it's pretty cool.
Turbo Chameleon 64, Flickerfixer, Turbo, REU (and A LOT more) for the Commodore 64
Omnivore is a cross-platform app for modern hardware (running linux, MacOS and Windows) to work with executables or media images of Atari 8-bit, Apple ][+, and other retrocomputer machines and game consoles.
Its goal is to provide all the niceties of modern GUI-based debuggers in a more lightweight and keyboard-friendly package. PuDB allows you to debug code right where you write and test it - in a terminal. Strongly reminiscent of the old-school Turbo IDE for DOS. Syntax highlighting, stack tracing, breakpoints, variable tracking. Cursor key and vi keybindings for cursor movement. Module browser. You can even drop into a Python shell inside the current environment.
The debugger can be controlled from a separate terminal.
A disassembler for Windows. One of the best in the field, and v2.0 just went beta. It's shareware, though it doesn't appear to lack any functionality if you haven't purchased it yet.
FDBG is a code debugger for code running in user mode (ring 3) in long mode (i.e., 64-bit native mode) on AMD CPUs. Ports for Windows and Linux are available. Written entirely in assembly language, includes source code. Extremely small executable.
BinNavi is a tool for performing static and dynamic reverse engineering of executables for a number of platforms - x86, ARM, PowerPC, and MIPS. Can connect to remote debuggers on other systems to examine running code. Extensible with scripts, can annotate call flow graphs. The source is on Github: https://github.com/google/binnavi
This is a free ebook about using the debugger/hex editor Radare2. It teaches basic techniques for using Radare2 all the way up to reverse engineering 64-bit executables. Free to download.