slashbinbash.de / Freeware Recommendations

Analysis

API Monitor
Monitors Windows API calls of running programs
OllyDbg
32-bit assembler level analysing debugger
Radare2
Reverse engineering framework
Sysinternals Suite
Collection of useful troubleshooting utilities
WinDirStat
Disk usage statistics viewer and cleanup tool
Windows Performance Toolkit
Performance monitoring tools that produce in-depth performance profiles
Wireshark
Program for network traffic capturing and analysis

Archiver

7-Zip
File archiver with a high compression ratio

Emulation

BGB
GameBoy and GameBoy Color emulator and debugger for Windows
DOSBox
DOS emulator
FCEUX
Nintendo Entertainment System (NES) and Famicom Disk System (FDS) emulator
Emulicious
Game Boy, Game Boy Color, Master System, Game Gear and MSX emulator

Games

Battle for Wesnoth
Turn-based tactical strategy game with a high fantasy theme
Cataclysm: Dark Days Ahead
Turn-based survival game set in a post-apocalyptic world
Dungeon Crawl Stone Soup
Roguelike dungeon crawler
Dwarf Fortress
Fantasy simulation
Freeciv
Remake of the original Sid Meier's Civilization
NetHack
Text-based fantasy RPG dungeon crawler with procedural generation
OpenRA
Remake of Command and Conquer: Red Alert with many improvements
OpenRCT2
Open source RollerCoaster Tycoon implementation with many improvements
OpenTTD
Open source simulation based on Transport Tycoon Deluxe
POWDER
Oldschool roguelike with simple graphics
Quake Live
Play Quake 3 Arena online
Simutrans
Transportation simulation game similar to Transportation Tycoon
Tales of Maj'Eyal
Tactical RPG roguelike

Graphics

Alchemy
Program for creating abstract art
Blender
3D modeling program
GIMP
Image manipulation program similar to Photoshop
GrafX2
bitmap paint program inspired by ​Deluxe Paint
Inkscape
Vector graphics editor
Krita
Professional open source painting program
MagicaVoxel
8-bit voxel art editor
Paint.NET
Very basic image manipulation program similar to MS Paint
yEd
Powerful diagram editor that can be used to generate drawings of diagrams

Internet

Chrome
Google's web browser
Discord
Voice and text-chat application for gamers
FileZilla
open-source FTP client
HexChat
IRC client based on X-Chat
PuTTY
Telnet/SSH client
Thunderbird
E-mail client, calender, and address book

Multimedia

Audacity
Audio editing and recording software
DaVinci Resolve
Professional video editing software
OBS Studio
Open source software for video recording and live streaming
ScreenToGif
Screen, webcam and sketchboard recorder with an integrated editor
Sekaiju
MIDI sequencer/editor software
Shotcut
Open source, cross-platform video editor
Sidplay2
Plays SID files (C64 music)
NSFPlay
Plays NSF files (NES music)
VLC
Sophisticated multimedia player

Office

MiKTeX
TeX implementation with additional tools and content, comes with the TeXworks editor
LibreOffice
Program suite similar to Microsoft Office with additional features
PDF Split and Merge
Does what the name says
TeXworks
Minimal but very reliable LaTeX editor

Programming

Eclipse IDE
Development environment primarily for Java applications
Git
Distributed version control system
HxD
Powerful hex-editor and disk-editor
Notepad++
Extended Notepad with syntax highlighting, spell-check, macros and more
Visual Studio Code
Cross-platform code editor, debugger, GIT support, etc.
Visual Studio Community
Free version of Microsoft Visual Studio
WinMerge
Differencing and merging tool that can compare folders and files

Scorewriter

LilyPond
Text based music notation program
MuseScore
Music composition and notation software

Trackers

AdlibTracker
OPL3 FM-chip tracker
DefleMask
Multi-system chiptune tracker (SEGA, Nintendo, C64, etc.)
FamiTracker
NES/Famicom chiptune tracker
GoatTracker
C64 chiptune tracker
LittleGPTracker
Tracker based on LSDJ
MilkyTracker
Tracker based on FastTracker 2 (XM format)
OpenMPT
Supports XM, IT, S3M, MOD, and MPTM format
SchismTracker
Tracker based on ImpulseTracker (IT format)
SunVox
Advanced modular tracker

Instruments/Effects

BR404
farbrausch synth
BR808
farbrausch synth
GeneralUser GS
GM and GS compatible SoundFont bank
Dexed
FM synth that is closely modeled on the Yamaha DX7
OmniMIDI
Software MIDI synthesizer
PG-8X
Synth inspired by the JX-8P
Synth1
Classic free VST
VCV Rack
Open-source virtual modular synthesizer

Virtualization

VirtualBox
Computer virtualization tool
WinCDEmu
Mounts ISO, CUE, NRG, MDS/MDF, CCD, IMG images