Information:
How to Surf More Securely
How to Stay Safe While Online
What Else Have You Just Downloaded?
How to Block Bad Websites
How to Tell If A Website Is Dangerous
How to Remove Ads, Wasted Page Space and Annoying Content
14 Mozilla Articles to Help Make You a Better and Safer User of the Firefox Browser
A comprehensive list of Firefox privacy and security settings

Website safety checking:
Subsections follow.

1. Information:
Best Free Internet Safety Check

2a. AV browser add-ons:
Microsoft Defender Browser Protection (Ch)
Avira Browser Safety (FF,Ch,IE)
avast! Online Security (Ch,IE)
Bitdefender TrafficLight (FF,Ch,OB)
Comodo online security (Ch,FF)
Malwarebytes browser extension (Ch)
McAfee WebAdvisor (FF,Ch,IE)
Panda safe web (Ch)
AVG Secure Search (FF,Ch,IE,OB)
G Data CloudSecurity (FF,IE)
Trend Micro Browser Guard (IE)
Dr.Web LinkChecker (FF,Ch,IE)

2b. Other browser add-ons:
WoT - Web of Trust (AB)
Webutation (FF, Ch)
LinkExtend (FF,Ch)
Netcraft Extension (Ch, FF, OB)
Sitehound
Web Security Guard (IE,FF)
BrightCloud Toolbar (FF,Ch)
Trust My Web (FF,Ch)
SafeLinks FREE (Ch)
Anti-phishing Domain Advisor
Unveil Technology Webfilter Toolbar
IDND (FF)
PhishTank SiteChecker (FF)
FB Phishing Protector (FF)
SmartScreen Filter (IE)
Trustwave SecureBrowsing (FF,IE,Ch,OB)
VT Browser Extensions (FF,Ch,IE)
Malware Search (FF,Ch)
vURL Online (IE)
Quttera URL Scanner (Ch)
Flag for Chrome (Ch)
Flagfox (FF)
ShowIP (FF)
CallingID (FF,Ch,IE)
IPvFox (FF)
cyscon Security Shield (FF)
Botfree EU -list

3. Web applications:
VirusTotal
Zulu URL Risk Analyser
NoVirusThanks
Dr.Web
Comodo
Online link scan
Web of Trust
ScanURL
UrlVoid
IPVoid
Google
Unmask Parasites
Webutation
Norton Safe Web
AVG
McAfee: SiteAdvisor ; Threat Intelligence ; TrustedSource
F-secure
TrendMicro
PC Tools Browser Defender
K9 Web Protection
Websense ; SWF
Sophos
Brightcloud
Finjan URL Analysis
MalwareURL
Web Security Guard
Unveil
Sucuri SiteCheck
Wepawet
urlQuery
vURL Online
Quttera
Monkeywrench
Web Inspector 

4. Windows applications:
AVG LinkScanner
Quttera URL Scanner for Windows
Ad-Aware Web Companion

Anti-malicious/potentially unwanted browser add-ons:
Shield for Chrome (Ch)
Extension Defender (FF, Ch)
Privacy Guard (Ch)

Anti-browser tampering:
HitmanPro.Alert; Features of free vs. paid version
BrowserProtect (FF, Ch, IE)
Public Fox (FF)
Preferences Monitor (FF)
Secure Profile (Ch)

Protection against scripts:
Click-to-play (FF,Ch)
uBlock (FF, Ch, OB); uBlock Origin (FF, Ch, OB)
NoScript (FF)
JSGuard (Ch, FF)
uMatrix (Ch, FF, OB)
NotScipts (Ch,OB)
ScriptSafe (Ch)
YesScript (FF)
QuickJava (FF)
Quick Javascript Switcher (Ch)
ScriptBlock (Ch)
Script Defender (Ch)

Protection against mining:
No Coin (Ch)
MinerOff
Miner Block (Ch)

Protection against Adobe Flash:
Flashblock (FF, Ch)
FlashControl (Ch)
Clean the junk (FF, Ch)

Ad blocking:
AdGuard Home
Adblock Plus (FF, Ch); blocklists
Element Hiding Helper for Adblock Plus (FF)
Adblock Lite (FF)
AdBlock (Ch,OB)
Ad Muncher
AdFender (AB)
Adsweep (Ch, AB)
Simple-adblock (IE)
AdblockIE (IE)
Karma Blocker (FF)
AdvertBan (FF)
Bluhell Firewall (FF)
Ad-Aware AdBlocker (AB)
How to Remove Google Text Ads
Ad-Blocker for Gmail (FF,Ch)
Css AdBlock (FF,Ch,OB)
Quero Toolbar (IE)
Diladele Web Safety (AB)
Webmail Ad Blocker (FF,Ch)
AdNauseam (FF)
10 Ad Blocking Extensions Tested for Best Performance

Pop-up blockers:
Best Free Popup Stopper
Adblock Plus Pop-up Addon (FF)
Better Pop Up Blocker (Ch)
PanicWare Pop-Up Stopper (FF, IE)
EMS Free Surfer (IE)
Popup Blocker Pro (Ch)
JavaScript Popup Blocker (Ch)
Google Toolbar (IE)
Poper Blocker (Ch)

Safer downloading:
µTorrent Virusguard
Team Cymru (FF)
Check my Torrent IP
Trusted Downloads
Fireclam (FF)

Safer online shopping:
Shopping assistant
Zscaler Safe Shopping (FF)

HTTPS validation:
Certificate Patrol (FF)
Perspectives (FF, Ch)
SaferChrome (Ch)
SSLGuard (FF)
Calomel SSL Validation (FF)
Unencrypted Password Warning (Ch)
Convergence (FF)
Heise SSL Guardian
SSL Blacklist (FF)
PasswordFail Extension (Ch)
SSL Collection (FF)
See also in this list: Force HTTPS

Updating browser and add-ons:
Qualys BrowserCheck (FF, Ch, IE, OB)
Mozilla Plugin Check
Alternative Flash Player Auto-Updater
SecBrowsing (Ch)
SurfPatrol (Ch, OB)

Browser data backup and synchronization:
Best Free Bookmark Syncronizer
FavBackup
Xmarks (FF, Ch, IE, OB)
FEBE (FF)
Google Bookmarks (AB)
Sync2It (FF, IE)
Delicious (AB)
Diigo (AB)
Favekeeper
Linkman Lite (FF,Ch,IE,OB)
OPML Support (FF)
More

Browser data cleaning:
Click&Clean (FF,Ch)
Preferences Cleaner (FF)
eCleaner (FF)
IE HistoryView
BrowsingHistoryView (IE,FF,Ch,OB)
Iron Cleaner (Ch,OB)
Privacy Agent
History Eraser (Ch)
OneClick Cleaner for Chrome (Ch)
Clear Console (FF)

Short URLs:
Subsections follow.

1. Unshortening short URLs:
bit.ly Browser Extensions (FF,Ch)
Untiny url (AB)
TrueURL (FF, IE)
longurlplease (AB)
LongURL (FF)
URL X-ray (AB)
View Thru (Ch)
Unshorten URL
Unshorten.it (FF,Ch)
URL Uncover (FF,Ch)

2. Safer URL shorteners:
mcaf.ee (Ch)
scr.im

Text recovery:
Lazarus (FF, Ch)
Textarea Cache (FF)

Other:
Online tools for surfers and webmasters
SpyBHORemover
Silent Block (FF)
BlockSite; Plus (FF)
HTTP Content Security Policy Detector (FF)
Clickjacking Defense - Declarative Sec Detector (FF)
Remove It Permanently (FF)
Readability (AB)
TidyRead (FF,Ch)
Shortmail 
Kristal Safe Way
Link Location Bar (FF)
Zscaler Tools
IEZoneAnalyzer (IE)
Menu Editor (FF)
Password Alert (Ch)
ConfigFox (FF)

Read/Post comments