GDB

GDB, the GNU Project debugger, allows you to see what is going on `inside' another program while it executes

IDA Pro

A powerful disassembler and a versatile debugger

Radare2

A free/libre toolchain for easing several low level tasks like forensics, software reverse engineering, exploiting, debugging, ...

Hopper

Hopper Disassembler, the reverse engineering tool that lets you disassemble, decompile and debug your applications

Strace

strace is a diagnostic, debugging and instructional userspace utility for Linux

ILSpy

ILSpy is the open-source .NET assembly browser and decompiler

Jpexs

Opensource flash SWF decompiler and editor. Extract resources, convert SWF to FLA

Uncompyle2

A Python 2.7 byte-code decompiler, written in Python 2.7

HxD

Fast hex editor which, additionally to raw disk editing and modifying of main memory (RAM), handles files of any size

Binwalk

Firmware (and arbitrary file) analysis tool

Foremost

Finds stuff in binary files and recover it

TrID

Utility designed to identify file types from their binary signatures

Grep (PNG offset)

grep -oba PNG <binary file>

Binwalk (Extract all)

binwalk --dd='.*' <filename>

JD-GUI

Standalone graphical utility that displays Java source codes of “.class” files. Java class files.

Dex2jar

Android decompiler dex and class files from apk

PE Explorer

Open, view and edit a variety of different 32-bit Windows executable file types

Qira

Competitor to strace and gdb

CFF Explorer

Full support for PE32/64, process viewer, .NET, rebuilder, hex, import adder, signature scanner, signature manager, extension support, scripting, disassembler, dependency walker

ResourcesExtract

Small utility that scans dll/ocx/exe files and extract all resources (bitmaps, icons, cursors, AVI movies, HTML files, and more...)

Androguard

Full python tool to play with Android files DEX, ODEX and APK

Apktool

Reverse engineering Android apk files

Binary Ninja

A New Type of Reversing Platform

Boomerang

Decompiler x86 (IA-32 only), PPC, ST20 files like ELF, PE, DOS MZ, DOS/4GW LE, Mach-O to high-level language output C

Ghidra

A software reverse engineering (SRE) suite of tools developed by NSA's Research Directorate in support of the Cybersecurity mission

Autopsy

Autopsy is the premier end-to-end open source digital forensics platform

OneGadget

The best tool for finding one gadget RCE in libc.so.6

Binutils

This is in most linux distributions default, but still it's important to know the tools. So check out the link! This is etc where strings, objdump is from.

Krakatau

Java decompiler, assembler, and disassembler

WinDbg

The Windows Debugger (WinDbg) can be used to debug kernel-mode and user-mode code, analyze crash dumps, and examine the CPU registers while the code executes

Xocopy

xocopy is a program that can copy executables with execute, but no read permission. It has been tested on FreeBSD and Linux kernels 2.[246].x

Xxxswf

Python script for carving, scanning, compressing, decompressing and analyzing Flash SWF files. The script can be used on an individual SWF, single SWF or multiple SWFs embedded in a file stream.

VirusTotal

Analyze suspicious files and URLs to detect types of malware, automatically share them with the security community

UPX

UPX - the Ultimate Packer for eXecutables

Pwninit

pwninit - automate starting binary exploit challenges.

GEF

GEF (GDB Enhanced Features) - a modern experience for GDB with advanced debugging features for exploit developers & reverse engineers

Patchelf

A small utility to modify the dynamic linker and RPATH of ELF executables

Checksec.sh

Checksec is a bash script to check the properties of executables (like PIE, RELRO, Canaries, ASLR, Fortify Source)

Cheat-engine

Cheat Engine. A development environment focused on modding. Wont recommend it due to suspicious addsense usage but a good starting point for editing live memory space on windows.