Realize that some of these programs may need to be unzipped, so see this list of free file unzippers to find a program that can extract compressed files.
Note: If you want something more permanent, see some reviews of professional antivirus software.
1. ClamWin Portable
ClamWin Free Portable Antivirus Scanner Features:
- Scheduled virus scans
- Automatic definition updates
- Plugin for Microsoft Outlook to scan email messages
- Scan just folders or individual files
Download ClamWin Portable for Free
2. Kaspersky TDSKiller Portable
Kaspersky TDSKiller Free Portable Antivirus Scanner Features:
- Scans and removes rootkits
- Can fight against many malicious programs (view them all on Kaspersky's website)
Download Kaspersky TDSKiller Portable for Free
3. McAfee Stinger Portable
McAfee Stinger Free Portable Antivirus Scanner Features:
- Detects many different virus variants
Download McAfee Stinger Portable for Free
4. Spybot - Search & Destroy Portable
Spybot - Search & Destroy Free Portable Antivirus Scanner Features:
- Scan and removes malware and rootkits
- Immunize system
- Only one update per week
Download Spybot - Search & Destroy Portable for Free
5. HijackThis Portable
HijackThis Free Portable Antivirus Scanner Features:
- Scan registry for possible unsafe changes
Download HijackThis Portable for Free
6. Remove Fake Antivirus
Remove Fake Antivirus Free Portable Antivirus Scanner Features:
- Remove programs that pretend to be real antivirus software
Download Remove Fake Antivirus for Free
7. Comodo Cleaning Essentials
Comodo Cleaning Essentials Free Portable Antivirus Scanner Features:
- Stop untrusted processes
- Remove rootkits, hidden files, and malicious registry keys
- Run a Smart Scan, Full Scan, or Custom Scan to scan just memory, boot sector, critical areas, hidden registry objects, or hidden files and folders on any attached drive
8. Norton Power Eraser
Norton Power Eraser Free Portable Antivirus Scanner Features:
- Rootkit scanner
- Run a Norton Cloud lookup on a file or folder, which uploads data online to do a scan
- Start a system scan of the drive that has Windows installed
- Can also scan another drive if you have multiple operating systems installed
9. Trend Micro HouseCall
Trend Micro HouseCall Portable Antivirus Scanner Features:
- Full scan, custom scan, and quick scan options
- Find viruses, worms, Trojans, and spyware
More Free Portable Antivirus Programs
In addition to the above, here are several more virus scanners you can try that are completely portable and free:- Norman Malware Cleaner
- eScan AV Anti-Virus Toolkit (MWAV)
- Microsoft Security Scanner
- Emsisoft Emergency Kit
- Zillya! Scanner
- Panda Cloud Cleaner
- Rizone Virus Cleaner - ViruClean
- Dr.Web CureIt
- aswMBR
- AVZ AntiViral Toolkit
- Stream Armor
- If you can't use Google Chrome to download this, use a different web browser like Firefox
- Spy DLL Remover
- Like Stream Armor, you must use a web browser other than Chrome to download this
- ESET (direct link)
- Not truly portable, but it asks to uninstall itself after you're done using it
- Ashampoo Virus Quickscan