Information:
Understanding tech language: The difference between malware and a virus
Not All “Viruses” Are Viruses: 10 Malware Terms Explained

Guides:
How to Know If Your Computer Is Infected
How to Clean An Infected Computer
The Basics of Manual Malware Identification and Removal
Elitekiller
Select Real Security
Majorgeeks: 1; 2
Bleepingcomputer
Geeks to Go
Deletemalware
Remove-Malware.com
overclock.net
MakeUseOf
How to remove a virus when your computer won't work

Forums:
Bleepingcomputer
Dslreports
Malware Removal
Geeks to Go
What the Tech?
Tech Support Forum
Majorgeeks

General-purpose scanners that use signatures:
Subsections follow.

1. Applications that work within a Windows installation:
Subsections follow.

1.1. Information:
Best Free Trojan Horse Scanning And Removal Software
Best Free Spyware And Adware Remover
23 Free On-Demand Virus Scanners (with reviews)
11 Free Online Virus Scanners (with reviews)

1.2. One scanning engine:
Subsections follow.

1.2.1. Can remove malware (for the free version, if there is also a paid version):
9-Lab Removal Tool
Avira Command Line Scanner; Scancl GUI
Avira PC Cleaner
Cezurity Antivirus Scanner
ClamWin; ClamWin Portable
ComboFix
Comodo Cleaning Essentials
Dr.Web CureIt
eScanAV Anti-Virus Toolkit
ESET Online Scanner
F-Secure Online Scanner
Kaspersky Virus Removal Tool
Malwarebytes Anti-Malware
Zemana AntiMalware
McAfee Stinger
Microsoft Malicious Software Removal Tool
Microsoft Safety Scanner
Norascan
Norton Power Eraser
Panda Cloud Cleaner; Panda Cloud Cleaner portable version
RogueKiller
Sophos Virus Removal Tool
Spy Emergency (trial; on-demand functionality is still available after trial period is over)
Spybot - Search & Destroy; portable
Superantispyware; portable
Trend Micro Anti-Threat Toolkit
Trend Micro HouseCall
Trend Micro Sysclean (command-line and GUI scanner)
Vba32 Console Scanner (command-line scanner)
VIPRE Rescue (command-line scanner)
Webroot SecureAnywhere Antivirus (trial; good at removing malware)
Zillya! Scanner
Quickheal
Botfree EU -list
Adlice Diag

1.2.2. Can't remove malware (for the free version, if there is also a paid version):
Bitdefender 60-Second Virus Scanner
Bitdefender QuickScan
BullGuard Online Virus Scan
Kaspersky Security Scan
McAfee GetSusp
McAfee Security Scan Plus
Norton Security Scan
Panda ActiveScan
Quick Heal Online Scan

1.3. Multiple scanning engines:
Subsections follow.

1.3.1. Can remove malware (for the free version, if there is also a paid version):
Emsisoft Anti-Malware
Emsisoft Commandline Scanner
Emsisoft Emergency Kit
HitmanPro (can't remove malware after trial period is over)
herdProtect
Multi-AV Scanning Tool
AntivirusMulti: review; download

1.3.2. Can't remove malware (for the free version, if there is also a paid version):
Metascan Client
WinMHR

2. Live media:
Kaspersky Rescue Disk
Bitdefender Rescue CD; Creating a Bitdefender Rescue CD on a USB flash drive
Avira Rescue System
Dr.Web LiveDisk
F-Secure Rescue CD
Panda Cloud Cleaner Rescue ISO; Panda Cloud Cleaner rescue USB drive
AVG Rescue CD
Windows Defender Offline
eScan Rescue Disk
Arcabit Rescue Disk
Zillya! LiveCD
Vba32 Rescue
Comodo Rescue Disk
ESET SysRescue Live
G Data BootMedium (on Tools tab)
Sophos Bootable Anti-Virus
Trend Micro Rescue Disk
Avast Rescue Disk
Ubuntu Malware Removal Toolkit
Comprehensive List of 26 Bootable Antivirus Rescue CDs for Offline Scanning

Integrate multiple live media/ISOs into one live medium/ISO:
Sardu
YUMI
XBOOT
Easy2Boot

Scanners that use non-signature techniques:
Subsections follow.

1. General:
HitmanPro (use Early Warning Scoring mode to avoid use of signatures)
Microsoft System File Checker; Run System File Checker Offline
AVZ Antiviral Toolkit: home (translated to English); download (translated to English)
Norton Power Eraser
McAfee GetSusp
Malware Scene Investigator
RogueKiller
Quick Heal DNAScan
Norascan
NoVirusThanks Malware Remover
Hidden CMD Detector
DensityScout
Universal Virus Sniffer: English version; home (translated to English); review
TrustWalk

2. Alternate Data Streams:
StreamArmor
ADS Spy
StreamFinder
ADS Tool
AlternateStreamView

Anti-PUP (Potentially Unwanted Program):
What does Potentially Unwanted Program mean?
Best Free Spyware And Adware Remover
AdwCleaner
Junkware Removal Tool
Bitdefender Adware Removal Tool
Adware Removal Tool - www[DOT]techsupportall[DOT]com/adware-removal-tool/
Force Byte Detector
Toolbar Cleaner; review
avast! Browser Cleanup
Auslogics Browser Care
Smart Toolbar Remover

Anti-ransomware:
What Ransomware is and How to Deal with It
How to Deal with the Ransomware Called CryptoLocker
Ransomware: how to remove it, even when the computer does not boot?
How to Remove Ransomware
Removing 'Police-themed' Ransomware
Kaspersky WindowsUnlocker; Banner Removal
Unlock codes
HitmanPro.Kickstart (feature of HitmanPro, which removes malware only during trial period)
id Ransomware

Anti-rootkit:
Best Free Rootkit Scanner and Remover
How to Remove a Rootkit from a Windows System
Kaspersky TDSSKiller
GMER
GMER MBR rootkit detector
aswMBR
Malwarebytes Anti-Rootkit
Sophos Anti-Rootkit
VBA32 AntiRootkit
Kernel Detective
SpyDllRemover
Trend Micro RootkitBuster
Bitdefender Rootkit Remover
SanityCheck
McAfee Rootkit Remover
RootRepeal
Rootkit Unhooker
NoVirusThanks Ring3 API Hook Scanner
catchme
Oshi Unhooker
ESET Hidden File System Reader
AntiSpy
Getting rid of MBR Rootkit's (bootkit)
NoVirusThanks Anti-Rootkit
wincheck
Packed Driver Detector
ListParts
PC Hunter
PowerTool
List of Anti-Rootkits
15 AntiRootkits to Detect and Remove Malware that Uses Rootkit Technology
13 top best free rootkit removal (anti-rootkit) programs

Specialized applications:
Subsections follow.

1. Individual applications:
RKill
Detekt
Remove Fake Antivirus
RegAuditor
RemoteDLL
UnDLL 
SecureMybit DH Scan
Simple Machine Protect

2. Applications from anti-malware vendors:
Bitdefender
Kaspersky: 1; 2
ESET
Symantec
AVG
Quick Heal
K7
G Data (see Tools tab)
Trend Micro
Avira
McAfee

Single file analysis:
Subsections follow.

1. Information:
How to Tell if a File is Malicious
What Else Have You Just Downloaded?

2. Online scanners that use signatures:
Subsections follow.

2.1. Information:
11 Free Online Virus Scanners (with reviews)

2.2. One scanning engine:
Dr.Web Online Scanner
FortiGuard Online Virus Scanner
avast! Online scanner
ThreatExpert Online File Scanner
NANO Antivirus Online scanner
Comodo File Verdict Service ; Valkyrie Uploader

2.3. Multiple scanning engines:
VirusTotal ; VirusTotal Uploader
VirusTotal Scanner
PhrozenSoft VirusTotal Uploader
VT Hash Check
Jotti's malware scan ; JottiQ
Virscan
Metascan Online
Gary's Hood Online Virus Scanner
Hyperball
Crystal X
Sigcheck; SigcheckGUI

3. Non-signature techniques:
Subsections follow.

3.1. Without executing the file:
PeStudio
PeSweep
ExeScan
Malware Analyzer
Portable Executable Scanner
Sigcheck; SigcheckGUI
FileAlyzer
Comodo File Verdict Service ; Valkyrie Uploader
Pescanner
FileScanner
VirusTotal (see other tabs) ; VirusTotal Uploader
Norton Power Eraser (Advanced Options -> Reputation Scan)
Hyperball
Peek 

3.2. Online behavioral analysis:
ThreatExpert
GFI sandbox
Comodo Instant Malware Analysis
Comodo File Verdict Service ; Valkyrie Uploader
Anubis
Joe Sandbox
Xandora
ViCheck
Payload Security
Malwr

Signature definition files:
Avast
AVG
Avira
Bitdefender
ClamWin
Comodo
Emsisoft
F-Secure
IKARUS
K7
Kaspersky
MalwareBytes
McAfee
Microsoft
Nano
Panda
Quick Heal
Sophos
Spybot
Superantispyware
Symantec
Trend Micro
Twister
VIPRE
Zillya

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