1.Avast Free Antivirus:-

Avast Free Antivirus? provides the extremely important security you need to protect your PC from hackers.

Features:-

Antivirus and Anti-malware
Home Network Security
Browser Cleanup
SmartScan

Download link :-

https://www.avast.com/en-in/download-software

2.AVG AntiVirus Free:-

Award-winning antivirus
Detects, blocks & removes virus and spyware.

Features:-

Blocks Viruses, Spyware and Malware
Protects from Malware infected links
Permanently Deletes Files Securely

Download link :-

?http://free.avg.com/ww-en/download-free-all-product

3.360 Total Security:-

360 Total Security offers your PC complete protection from Viruses, Trojans and other emerging threats

Features:-

Full Check-(Check the overall condition of computer)
Virus Scan -(Antivirus engines from 360 Cloud Engine,360 QVMII, Avira and BitDefender)
Speedup– (Manage and optimize your system services, boot up items and plugins)
Cleanup– (Cleanup frees your disk space by removing junk files and plugin which can improve system performance)
Protection- (Protection offers 4 different user selectable modes – Performance/Balanced/Security and Custom
each mode offers a different level of protection from malware, phishing attacks and backdoors.)
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Download link :-http://www.360totalsecurity.com/en/

4.Comodo Internet Security:-

All best basic security with firewall with full functionality

Download link:-

https://www.comodo.com/home/internet-security/free-internet-security.php

5.Bitdefender Antivirus Free Edition:-

Very light antivirus only basic security and very limited functionality without inbuilt firewall but very powerful database to detect virus on computer .

Download link :-

http://www.bitdefender.com/solutions/free.html