Whilst paid tools and software tend to get the job done easier and almost in less time you can still find a wealth of software and online tools you can use totally for FREE.
Go and check it out, you will be amazed at what you can get done for FREE.
Link Research, Technical SEO
Worried about Google’s Penguin algorithm hitting you for over-optimized anchor text? Simply type in your URL for a full report of which links might raise flags.
Tools Suite, Diagnostic
Similar in function to Google Webmaster Tools, Bing offers a suite of interesting research tools and resources for webmasters.
Most people use Bitly for URL shortening, but the real power of this platform comes from its analytics.
Boomerang lets you follow up on emails, even when you forget. Great for link building or any time you send a lot of emails.
Optimize your online social media sharing. Buffer allows you to share with your audience at the optimal times for greater visibility.
Use BuiltWith to discover what technology nearly any website was, well, built with. Great for competitive intelligence as well.
Link Building, Tools Suite, Email
Most people know Buzzstream as an outreach platform, but they also offer a number of free link-building tools. This company gets it.
Google+ analytics ramped up. Free resource to track your followers and analyze your shares. See how many followers you’ve gained over time.
This tool from SEOgadget helps you plan your content strategy intelligently, using keyword research and estimating your audience size.
Despite the rise of Google Docs, Word still dominates much of the world. Copying and pasting has always been a hurdle, but this tool makes it easy.
Copyscape serves both as a plagiarism checker and a duplicate-content checker. Great to use if your content has been distributed across the web.
This magic extension for Chrome not only helps you find important broken links, but also tells you if the links point to an available domain.
Email Format helps you find the proper structure for thousands of companies and organizations across the web.
The tool to replace Google’s popular keyword tool has been derided by some, but still offers data not available anywhere else.
The most popular of all the analytics tools available, Google Analytics continually innovates and sets the standard.
The Google Analytics API is great for building custom reports and tools, and also for pulling data straight into Excel or Google Docs.
Tools, data, and insights to improve your page speed. Page speed is correlated with better rankings and user engagement, so this matters.
Drawing on vast public databases, Google public data offers a great starting point for content research, infographics, and more.
Technical SEO, CRO
That SEO Mofo! Use this tool to see how your snippet may appear in Google’s search results. Add structured data, review stars, and more.
Structured Data, Technical SEO
If you use Schema.org microformats or any other type of structured data, this tool will verify your markup.
See what’s trending in Google search results and view keyword search popularity over time. A must for trends.
Tools Suite, Diagnostic
The interface recently received an overhaul, and Google Webmaster remains a must-have resource of diagnostic and health tools for site owners.
IFTTT stands for IF This, Then That. The tool allows you to create automatic triggers between various apps, like Gmail and Twitter.
The Ninjas are some of the best SEOs and online marketers out there, and they’ve put some of their best tools online for free.
This nifty analytics tool alerts you anytime someone links to your website. Great for outreach and intelligence gathering.
Need to send an email to an untested address, but you don’t want to spam them? Check it first with this mail tester to verify.
SERP Tracking, Moz
Want to know if Google is testing its algorithm this week? MozCast gives you a daily weather report to track changes in the SERPs.
Link Building, Content
Guest blogging is still alive and thriving. MyBlogGuest helps you find the good opportunities out there.
This awesome tool connects with your Google Analytics account to help you see if and when you’ve been hit by Google Algorithm updates.
Pingdom offers an entire suite of speed tools to help analyze page load, DNS issues, and connectivity.
Piwik is a lightweight web analytics solution, and a great alternative to Google Analytics.
This light and easy desktop tool checks rankings with the click of a button. Quick, easy and free.
Email, Link Building, Productivity
Rapportive works with your Gmail inbox to give you near-instant rich contact information for almost everyone you want to reach. A must-have for marketers.
Robots.txt, Technical SEO
Use robots best practices and discover hidden errors in your robots.txt files that may cause search engine crawling problems.
Structured Data, Technical SEO
Everyone loves using Schema.org, but the microformats are difficult to write by hand. This generator from the folks at Raven simplifies the task.
Tools Suite, Analytics, Link Research
SEER opened up its internal toolbox for everyone in the world to use. These are the same tools used in-house at SEER, and they rock.
Tools Suite, Toolbar, Technical SEO
On of the most popular tools available, The SEO Toolbar puts a ton of information at your fingertips including backlinks and competitive research.
Tools Suite, Analytics, Social
You don’t need to be an Excel ninja to use Niels Bosma’s SEO Tools for Excel. This plugin does so many things many SEOs won’t work without it.
API, Link Research
The SEOgadget Links API lets you easily gather not only backlink data but contact information as well. A huge time saver.
This suite of tools from the Gadget lab includes several Excel plugins, a content strategy generator, and more.
Toolbar, Tools Suite, Technical SEO
More raw data than any other SEO toolbar out there.
Want to know how any piece of content was shared socially across the major services? This is the tool to use.
Harnessing the combined statistics of Google+, Twitter, Facebook, and more, the SharedCount API puts a ton of social data at your fingertips.
Content, Technical SEO
Use this tool to check for duplicate content issues. The Similar Page Checker will give you a score of how closely the HTML of two pages resemble each other.
Google offers a slew of free, top-notch sitemap generators. Most of these live on your server and generate new sitemaps automatically.
How much reach and social authority do your followers have? How about the people you’re trying to connect with? The free Social Authority API will tell you.
Social Crawlytics allows you to conduct competitive research by showing you your competitors’ most-shared content. Lots of other features as well.
Social mention offers real-time social media search and analysis. Enter a search term and see who’s sharing what, right now.
Some of the best tools solve the simplest problems. Text cleaner cleans up all kinds of text formatting when copying and pasting between aplications.
Every SEO loves Ubersuggest for its ease of use and wealth of keyword research ideas. Utilizing the power of Google Suggest, it returns hundreds of potential results.
A great tool for digging into server headers, canonical information, analyzing redirect problems and more.
Virant offers a number of high quality SEO tools to the public. These are often the same tools developed for the Virant team, opened up for public use.
Want to see the history of your website or your competitor’s site? The Wayback Machine allows you to step back in time and track important changes.
Quick and easy website speed tool. Offers suggestions for improving performance.
Create beautiful word clouds. Great for visualizations, graphics, and research.
Keyword Research, Tools Suite
In addition to its paid offerings, Wordstream offers a suite of free keyword tools offering access to thousands of keyword suggestions.
Diagnostic, Technical SEO
Winner of the ugliest-SEO-tool-on-the-planet award, Xenu is also one of the most useful. Crawl entire sites, find broken links, create sitemaps, and more.
XML-Sitemaps offers probably the easiest sitemap creation solution anywhere. Great for smaller sites when you need a sitemap in minutes.
If you could only choose one WordPress plugin for you site, the first would be from Yoast, and so would the second. This one sets the standard.
Offers video-specific analytics for YouTube videos. A must-have for YouTube video publishers.
Thats it, what a great list and all for free. Big thanks to Cyrus Shepard for providing such a great resource.