Free SEO Tools List

Hi everyone

This week I bring to you the biggest list of SEO tools, more importantly is that all these are absolutely free(by the time I incorporated them into the list) mentioned below along with what they actually are explained in a single sentence. I'll add more if any that I come across in future.
Also I request you to please comment below about any tool from the list that you have used earlier or have been using explaining about it so that it makes things bit easier for the next ones. And be sure to comment any new tool that I might have missed.
You may also be interested in few of my other posts on Keyword tools, softwares and websites; List of Backlinks Checker Tools, Websites and Softwares and lastly Useful Softwares and Tools for Online Business 

Get ready for the big list well arranged. Hope this post will be of good use to you all.

W3Counter	Displays reports on who found your website and how they got there
Piwik	Gives you full control of analytics on your desktop and on mobile
Clickmeter	Monitor marketing campaigns and conversions all in one dashboard
Clicky	Monitor traffic to your website in real time
StatCounter	Provides a basic interface for your website statistics
YouTube Analytics	Provides data and statistics on YouTube videos
GeoRanker	Real time analytics and reports geared towards local SEO
Panguin Tool	Shows Google Analytics in relation to major Google algorithm updates
Google Analytics	Track analytics of your website
Browser Extensions
LinkChecker plugin Firefox Plugin	Analyzes links on a webpage and highlights whether they are live or dead links
Kgen Firefox Plugin	Analyzes webpages for dominant keywords with content improvement suggestions
SEO Rank Checker	Check site rank position for designated keywords from your browser
Check My Links - Chrome Extension	Checks webpages for dead links
Google Results Bookmarklet	Compiles search results into easier to manage lists of URLs
GA Debugger - Chrome Extension	Debugs Google Analytics javascript code on websites
SearchStatus	Displays important site SEO performance data about a website
Sharemetric - Chrome Extension	Displays page social share count in toolbar
MozBar	Displays pagerank, page authority, and domain authority of a website in the browser toolbar
PageRank - Chrome Extension	Displays the current website’s pagerank in the toolbar
Live HTTP Headers	Displays the HTTP headers of a webpage while browsing the website.
Firebug	Gives you a techinical view of webpages with css, html, and javascript
SenSEO Firefox Plugin	Gives your webpage an on-page SEO report card
Page Monitor - Chrome Extension	Monitors webpages in the background for changes done to the page
SEO Doctor Firefox Plugin	Provides easy SEO diagnosis and troubleshooting for your website
SEOQuake	Provides helpful background information on websites you are visiting or websites in the SERPs
SEO SERP - Chrome Extension	Quickly lets you find what SERP position a webpage is for certain keywords
Get URLs from Search Results	Returns just a list of URLs from a search query
Scraper - Chrome Extension	Scrapes lists and fields of data on any website and exports them into a spreadsheet
Google Analytics Opt Out - Chrome Extension	Tells Google to not track your visits in Google Analytics
SEO Toolbar	View many different SEO related elements of a website all in the web browser
Competitive Analysis
Searchmetrics Visibility Charts	Analyze competitor SEO performance and keyword information
SEMrush	Indepth analysis of competition keywords and search data
Quantcast	Show traffic data for any website
SpyFu	View competitor adwords campaign information and keyword data
Content
Piktochart	Allows you to quickly and easily generate infographics without a designer
nTopic	Analyzes your website’s content and makes improvements according to your keyword
Copyscape	Check for duplicate content on your website across the web
Plagiarism Checker	Checks text for plagiarism across the web
MyBlogGuest	Connect with blogs and bloggers for guest blogging
Help a Reporter Out (HARO)	Connects reporters with sources that might be featured in high authority sites
Infogr.am	Create good looking infographics quickly and without a designer
Google Public Data	Publc data search resource for finding various statistics
Conversion Rate Optimization
Click Tale	Analyze customer experience with visualized and meased in-page behavior
Optimizely	Apply and monitor A/B tests to your website
Visual Website Optimizer	Perform a/b testing and multivariate testing on your website
Usability Hub	Shows people your site for 5 seconds and asks them questions about it to help you improve conversions
Desktop Applications
URL Explorer	Analyze your site for duplicate content, missing pages, and many other elements throughout your website
Keyword Pad	Batch process keywords for in depth keyword analysis
Xenu’s Link Sleuth	Checks websites for broken links
Traffic Travis	Complete SEO and PPC dashboard
Good Keywords	Manage keywords and create long tail keywords and keyword phrases
Screaming Frog	Performs extremely indepth analysis on website SEO elements
SEO PowerSuite	Reviews and analyzes your site’s SEO efforts
IIS SEO Toolkit	Toolkit for analyzing websites along with robots and sitemap features
Email
Banana Tag	Allows you to track emails, get open email notifications, and provides analytics on your sent emails.
Peepmail	Email finder for common contacts online
Boomerang	Email scheduling and followup for quick responses
Ontolo’s Prospect Filter	Filters previously already approached contacts from new prospect lists
Outreachr	Finds a list of websites and contacts according to what keywords you select
Linksy.me Email Guesser	Guesses email addresses and matches them to Rapportive in Gmail
Email Research Tool	Input the name and company of an individual and it will provide several search queries for finding their email address
Rapportive	Shows additional information about a contact from their email address right in gmail
Email Format	Shows probable email address formats for large websites and companies
MailTester	Validates if email address exists or not
Keyword Research
Keyword Density Analyzer	Analyzes URLs for on page keyword density among boxy text, links, and images
Google Places for Business Category Tool	Assists you in finding the correct Google Places category.
Bing Keyword Research	Bing’s Keyword Research tool with query volumes and suggestions
Term Explorer	Bulk keyword research and statistics tool
Trellian's Keyword Discovery	Compiles keyword search statistics for your keyword research
Keyword Niche Finder	Discover niches within a given keyword
Meta Keyword Research Tool	Get keyword suggestions from Google, Bing, and Youtube and email them to yourself.
Ontolo’s Keyword Generator	Generate keyword combinations from two lists of keywords
Ubersuggest	Input a query and ubersuggest will return a long list of ideas and suggestions on keywords and content topics
Keyword Eye	Provide in depth keyword research and reporting on your and your competitiors
Search Engine Optimization/KSP Tool	Provides convenient keyword statistics and search data
YouTube Keyword Suggestion Tool	Provides keyword suggestions and monthly search volume for YouTube promoted videos
Wordpot	Provides keyword suggestions with related daily searches
Negative Keyword Finder	Provides suggestions for negative keywords based on a given keyword
Microsite Masters	Rank tracking, automation, and ROI calculating for keywords and domains
Google Trends	Searches and keywords that are trending on Google at the moment
Keyword Suggestion Tool	Searches for relevant suggestions for any given keyword
Keyword Cloud Tool	Visual representation of the different keywords on a given webpage
YouTube Keyword Tool	YouTube keyword tool for finding keyword ideas for your YouTube videos
Link Analysis Tools
Disavow Link Analysis	Analyzes your Google backlinks for finding potential disavowed links
Ahrefs	Backlink Checker that shows links, linking domains, anchors, and best pages of a domain.
Open Site Explorer	Backlink Checker that shows links, linking domains, anchors, and best pages of a domain.
Majestic SEO	Backlink profile analysis and link database
Site Explorer	Checks for backlinks and provides additional link details
Remove'em	Checks URLs for over optimized anchor text
Fresh Link Finder	Discover fresh links to your website
Bing Link Explorer	Discovers backlinks for any website
Link Analysis Tool	Displays every link on a given URL with its anchor text and whether it is nofollow or not
Link Reporter	Displays how many links are on a page and separates internal, external, and nofollow links
Linkstant	Find out immediately when you receive new links to your website
Majestic SEO	Site explorer and backlink history checker
Mobile Apps
SEO & Link Analyzer	Analyzes link and SEO data for website URLs
mAnalytics	Android App for viewing Google Analytics
Analytics Tiles App	Dashboard for iOS devices that creatively displays analytics data
WebRank SEO	Display SEO ranking data on your Android device
SiteRank Lite	Displays Google PageRank and Alexa Rank for website URLs
SEO SERP APP	Displays keyword rank data and social shares for URLs
Woopra	Google Analytics dashboard for iOS devices
SEO watcher	Rank Tracking for Android devices
Productivity Tools
Yahoo Pipes	Automates common activities for saving lots of time
Ontolo’s Extract Unique Hostname	Extracts the unique hostnames from a list of URLs
Ontolo’s URL Reviewer	Open an entire list of URLs all at once in their own browser tabs
Remove Duplicate Items	Remove duplicate items from a list of things
Ontolo’s Remove URLs by Hostname	Remove URLs from a list that contain hostnames in another list
Ontolo’s Remove Duplicate Hostnames	Removes duplicate hostnames from a list of URLs by keeping the first instance of the hostname
Ontolo’s Count URLs and Hostnames	Returns the number of URLs or hostnames in a list of URLs
Resource Generators
Schema Creator	Automatically generates schema.org markup for different types of webpages
Local PPC Adwords & Keyword List Creator	Generate local adwords and keyword lists
XML-Sitemaps	Generate sitemaps for your website
Robots.txt Generator	Generates a robots.txt file for your website based on parameters you determine
Embed Code Generator	Generates an embed code for your content
Local Search Resource Generator Tool	Generates GEO Meta tags, GEO Sitemaps, hCard, and KML Location Code for local search optimization
Title & Meta Tags Generator	Generates titles and metas html markup
Geo Sitemap Generator	GeoSitemap and KML generator for local SEO
Local Business Schema (NAP)	Local business schema.org markup generator
Convert Word Documents to Clean HTML	Paste word document text into this tool and clean it up for HTML
Good Relations Rich Snippet Generator	Rich snippet generator for online businesses and stores online
Microdata Generator	Schema.org markup generator for local businesses
XML Sitemap Inspector	Validates and corrects sitemaps
Search Analysis
Google Places Tool	Analyzes Google Places listings and compares them to top competitors in the area
Cygwin	Compare rankings between you and your competitors for certain keywords
Compare Search Rankings	Compare the rankings of a website across multiple search engines for designated keywords
Free Keyword Rank Checker	Keyword rank check for specified domains and keywords
Google SERP Snippet Optimization Tool	Previews what your Google search result will look like in Google
Soovle	Quickly search across multiple searching platforms
Advanced Search Query Tools
Ontolo’s Link Building Query Generator	Generate link building search queries automatically based on your keyword suggestions
Outdated Content Finder	Provides search queries tailored to find outdated content that you can easily update
Chase the Footprint	Search query generator for finding link building opportunities
DropMyLink	Search query generator for finding link building opportunities
Link Building Query Generator	Search query generator for finding link building opportunities
Search Latte	Search query generator geared towards international SEO searches
SEO Analysis
Analytics SEO	Analytics and SEO analysis all compiled into one large SEO utility suite
Image SEO Tool	Analyzes images for best SEO practices in image optimization
Bing SEO Analyzer	Bing’s SEO analyzer that provides reports and analysis of your website’s on page SEO
Whitespark Local Citation Finder	Discovers additional search phrases for local SEO that your pages can easily be optimized for
Side-by-Side SEO Comparison Tool	Evaluates your on-page SEO efforts in comparison to up to 4 other websites
Seorch On-Page SEO Tool	Gives in depth analysis of a website’s on and off page SEO
Web Page Test	Provides an in depth evaluation of SEO elements on your website
Site Analysis
WebCEO	Allows your to research, promote, and track SEO elements of you and your industry
Google PageSpeed Insights	Analyze how long it takes your website to load
Google Webmaster Guidelines Check	Analyzes a site against Google Webmaster guidelines and provides suggestions for improvement
Bing Webmaster Tools	Bing’s Webmaster Tools for analyzing your site in Bing searches
Hubspot Marketing Grader	Check various areas of your website and grades you on your marketing efforts
Google Structured Data Testing Tool	Check website for structured data for search appearance
The Reaction Engine	Complete site analysis of on-page SEO
Rob Hammond's SEO Crawler	Crawls an entire website for potential SEO issues and displays relevant SEO information about each page
Alexa	Detailed analytics displayed for any website on the internet
SeoSiteCheckup	Detailed report on a site’s SEO
Keyword Density Analysis Tool	Determines what the keyword density is for a certain URL
GoingUp	Easily check the on-page SEO of any website including the keyword optimization for that page
SEO Crawler	Finds errors on your website and your competitors for best SEO practices
BuiltWith	Gives you valuable information as to what technologies are used on certain websites
WooRank	Gives your website a complete analysis of visitors, local, social, mobile, SEO, usability and technologies used
Nibbler	Gives your website a report card for the various elements that a website has
Google Webmaster	Google’s site analysis for optimizing various elements of your website
Sindice Web Inspector	Inspects/validates HTML against w3c.org validator
Cuutio	Monitors you website’s statistics and compares them to competitor’s
SEOMastering.com's SEO Audit	Performs a site worth analysis and SEO evaluation for a given URL
SimilarWeb	Presents data and analytics on a given website
BROWSEO	Quick and easy tools allows you to analyze your site and view it like a search engine would crawl it.
SEOptimer	Reviews and analyzes your site’s SEO efforts
GTmetrix	Scans your website giving you a detailed performance evaluation
Request Checker	Shows how many requests and services a webpage makes each time it loads
Spider Simulator	Shows you exactly how Googlebot views your website
Pingdom	Test page speed and determine exactly what is causing bottlenecks
W3C Feed Validation Service	Validate a website’s markup and provide correction suggestions
Sitemap Validator	Validate sitemaps and check them for errors
Google’s Safe Browsing tool	Website diagnostics for malware
Social Media Tools
Buffer	Allows you to schedule posts to major social networks ahead of time
Get Listed	Displays local business accounts that your company can easily obtain and/or does not currently have
Alternion	Links all of your social media and email accounts, displaying them all in one place.
TweetDeck	Manage multiple social media accounts and monitor interactions on Twitter
Hootsuite	Manage your social media presence across multiple accounts and schedule posts
Google SERPs Social Media Power	Analyze social media power of the domains ranked on SERPs
SharedCount	Check the number of social shares a certain URL has received
Social Media Count	Checks a link for how many social shares it has across several different channels
Author Backlink Crawler	Checks authorship of a URLs backlinks and displays how prominent those authors are
Youtube Reputation Checker	Checks your brand name for Youtube videos and shows you videos, views, and ratings
Social Mention	Discover social mentions about a given URL
Counting Tweets	Display the number of tweets a certain page has received
Pinalytics	Displays stats behind pinterest pins as well as its influence across other social media channels
Twitter Feed	Feed your blog or RSS feed directly to your Facebook, Twitter, or LinkedIn profile
subredditfinder.com	Find a relevant subreddit to share your content
Twellow	Find industry leaders and other Twitter users according to category
Twitter Counter	Get basic Twitter stats on you and your followers
Blog Social Analyzer	Input your blog’s RSS feed and it will return every blog post with how many social shares each one has
Facebook Page Insights	Insights on your audience and analytics on their interactions
followerwonk	Multiple tools for Twitter like bio search, user analysis, and analytics
CircleCount	Provides insights on Google+ accounts
Social Crawlytics	Provides social metrics for you and your competitors
Social Media Image Resizer	Resizes your images to be optimized for vairous social media accounts
Topsy	Search tweets for links, photos, videos and keywords and see how that topic is trending over time
backtweets	Searches for links on twitter
Tweriod	Tells you when your tweets will receive the most exposure
Social Media Analyzer and Tracker	View statistics for your various social media shares and have them tracked over time
Spreadsheet Tools
SEOgadget Extension for Excel	Allows you to conduct advanced Excel commands on SEO data with APIs from several different services
Content Strategy Generator	Assists you in developing content with generating ideas and showing recent content currently trending on certain topics and keywords
SEO Tools for Excel	Gives your excel document various SEO tools for better number crunching
Seer Toolbox	Spreadsheet that pulls in data from multiple SEO tools and services including Moz, Google Analytics, Google Scraper, Twitter, Klout, and more
Distilled’s Video Sitemap Guide	Video Sitemap Generator for self hosted videos
Web Utilities
IFTTT	Automate many different services to automatically perform different time saving tasks
KnowEm	Check for username, domain name, and patent availability for new brand names
Bulk HTTP Header Response Tool	Check multiple HTTP headers and compare them at once
SEO Cloaking Checker	Checks for search engine cloaking on given domains
GA Checker	Checks websites for missing Google Analytics and Adwords code
TextCleanr	Clean up text from formatting along with find and replace functionality
SimilarSites	Discovers similar websites to a given URL
NetComber	Displays the various websites owned by the same company
DNS Tool	DNS/WhoIs lookup tool
HTML Encoder/Decoder	Encodes/Decodes text into HTML friendly formats
Domain Extractor	Extracts the domain from a batch of URLs and exports into CSV
Extract Page Names from URLs	Extracts the page name from batches of URLs and exports into CSV
Extract Title and Metas	Extracts Titles and Metas from batch of URLs
Google Correlate	Find correllations in data according to Google search keyword phrases
moreofit.com	Finds websites similar to the one you point it to
Google Alerts	Get email updates for various alerts of new content
HTTP Header Viewer	HTTP header viewer for analyzing/diagnosing website issues
Wayback Machine	Internet archive of websites in the past allowing you to historically go to websites at a certain point in time.
Domain Dossier	Investigate domains and IPs with WhoIs info and DNS records
Ping-o-Matic	Lets search engines know you have updated your website or blog
URL Opener	Open a list of URLs in separate tabs
Extract Links from HTML	Pulls links from HTML and exports the links in CSV
Bitly	Shortens URLs and provide analytics on clicks
MX Toolbox	Shows domain MX records for websites you type in
Domain Report Tool	Shows domain pagerank and additional indexing data for giving domains
CloudFlare	Speed up website load times with CDN and other web performance services
Smart URL List Cleaner	Ultimate list trimmer and combiner for deduplicating and combining multiple URL lists together
Link Prospector	Uses a special algorithm to discover potential link building opportunities
Wistia	Video hosting with complete control over video settings with advanced features like email forms and heatmaps
Last Modified Date	View the date a website was last modified
Validation Tools
Bing’s Markup Validator	Bing markup validator analyzes your sites markup and validates proper markup code.
Robots.txt Checker	Checks syntax of robots.txt files
Robots.txt syntax checker	Robots.txt validator
XML Sitemap Validator	Validate current website’s sitemap
Frobee Robots.txt Checker	Validates a website’s robots.txt files
Wordpress Plugins
Google Sitemap Plugin	Adds a sitemap to Google Webmaster Tools from Wordpress
WP Social SEO Booster	Adds Facebook Open Graph, Twitter Card, and Google Rich Snippets to pages and posts for better social share appearances
Headspace2	Adjust every element of each post and page of a Wordpress website
Internal Link Builder	Allows you to designate certain keywords and phrases on your wordpress site to automatically be linked to internal pages
SEO Friendly Images	Automatically adds alt and title attributes to all wordpress images
Squirrly	Checks your blog content for elements of SEO and makes recommendations for changes
Google Analyticator	Easy install javascript for Google Analytics and displays data on the Wordpress dashboard
Basic SEO Pack	Easy Wordpress site optimization for SEO
WordPress schema plugin	Generate the schema.org markup for your wordpress site
Open Graph plugin for Facebook	Optimize metadata for properly displaying your posts and pages on Facebook
Yoast WordPress SEO Plugin	Optimize your entire wordpress site and its content and automatically generate sitemaps
SEO Ultimate	Optimizes several areas of your Wordpress site for SEO