This list has to be one of the most biggest and comprehensive list of Keyword Research Tools. I felt it is Important to make an Ultimate Authority List of Keyword Research Tools so people can find everything at one place (I myself was tired of looking at my bookmarks over and over again). I will make sure this list keeps on getting updated regularly. If you know any more keyword research tool which should be in the list, please put it as comment and I will add it here.
List of Free/Paid Web Based Keyword Research Tools
Popular web based Keyword Research Tools
1. Google Adwords - A tool with most trusted data IMO. Ever since Google has started showing number of searched for the keywords, the value of this tool has increased many folds as now you can youself calculate the KEI without needing any paid keyword tool
2. Keyword Tracker - Keyword tracker is there since a long time and though its long tail results often reported as highly oftargeted, they are still a good tool to work with. Personally I don’t think free wordtracker is going to help you much as most of the keywords it shows are already been targeted by marketers and website builders.
3. Keyword Discovery - Right now, one of my favorite free keyword tool along with adwords tool, though it too has given me some way of the mark results (keywords which it said will give huge traffic but after me being #2 in Google, I can barely see any traffic!). Anyway its free and gives more results than Wordtracker.
4. Wordze - I had tried wordze paid membership for couple of times (I think it was $8/day) and it looked alright to me. From my personal experience I can say that the keywords which wordze called really good to target were not that good, though I know this happens all the time. Rules like KEI > 10 means Great Keyword are grossly wrong. You can only found great keywords from experience, trial and error.
5. SEO Book Keyword Tool - Aaron’s Keyword Research tool gives lot of information for the keywords and is probably one of the most comprehensive keyword tools present right now on net in terms of breadth.
6. SEO Digger - SEO Digger is a Great tool to do competition keyword research. Just enter any url and SEO Digger will tell you for what keywords, the site is ranking at what position in Google. The data may be little outdated but still it do remarkable job.
7. Keyword Spy - I had never used keywordspy before writing this post. And now when I have used it (free trial version), I will say it looks good. I really can’t comment much but it is useful to search into PPC world and find what keywords your competitors are using for their PPC campaigns.
8. Spyfu - Spyfu is another good tool which helps you to explore your competitors keywords, for which keywords they are toping the serps.
9. Nichebot - I haven’t used nichebot since 2007 and they seems to have changed alot. They used to be alot like SEOBook’s current keyword search tool. RIght now it looks they are using API’s of wordtracerk/google/keywoddiscovery (which they were using earlier too) and offering some more refined stuff. I will explore them more later to see are they even offering any paid service or not.
Other web based Keyword Research Tools
1. Google Search Suggest - I am not sure many have realized this but this is super fast way to get related keyword searches for any keyword. Google not only suggest the keywords but also suggest the number of searched made.
2. MSN Adcenter Keyword Tools - Microsoft is offering some nice set of keyword tools which are worth looking at.
2. Google Sets - Google Sets is an excellent tool for people who are looking for related root keywords.
3. Google Related Keywords - This tool is Ontology based which finds Related Keywords just like google sets.
4. Keyword Research tool - This tool searches the top serps pages for the given keyword and find the kind of keywords they are having. The suggest may go little wrong but sometime but whatever I have seen so far, it looked pretty effective to me.
10. Keyword Data Miner Tool - Well right now the tool is not working for some reason but I have seen it people using it. I will again check later if that tools works and if it don’t, I will remove the link..
Keyword Tools suggesting Trends
1. eBay Pulse - Shows daily keywords trends that are hot on eBay,useful for research.
2. Yahoo! Buzz - Shows search keywords that are hot on a given day on Yahoo! Search..
3. Google Hot Trends - Shows keywords that are recently hot and also archives them
4. Google Trends - Shows seasonal search trends for most popular keywords.
5. Google Zeitgeist - Google Zeitgeist (geez, should have used a better name…) is a set of tools from google using which you can get past results. So you can know what keywords were hot last month or last summer.
6. AOL Search Hot Searches - Just like all other search engines, AOL also offers what keywords are searched most.
7. Ask Jeeves Interesting Queries - Ask jeeves also showing most searched keywords.
8. Lycos Hot 50 - Lycos too!
Remaining Keyword Research Tools
1. Thesaurus.com - You can use Thesaurus.com to get some relevant synonyms of keywords. This ofcourse gives a total new approach towards keyword research and I won’t go much into it but will cover than in some other Post.
2. Dependency-based Word Similarity - If you are into Information extraction and Retrieval stuff and are looking to do your own things, then you may like to see some of the tools listed here. Most of them are advanced keyword tools, even dealing with HMM.
3. Hitwise Search Intelligence - I am not sure about their current rates but its in mid $xx,xxx so they are obviously not right for most of the people here. I am just putting them as I have heard them to be good. If you are interested then you can contact them.
List of Desktop Keyword Research Softwares
1. Good Keywords - I had saw this tool in 2006 and immediately fall in love with it. Its a great small free software which suggest keywords, build keyword lists as well as suggest typo keywords.
2. IBP - I have used IBP in the past and can say its a good software (albeit very costly) for keyword research, specially if you are an organization.
3. SEO Elite - Its NOT free and I have heard mixed reviews about it but if you have spare money than it may be worth trying for.
Their are few more desktop based keyword tools but right now I am putting only these. Later on I will try to add more.
Dead Keyword Research Tool
1. Overture - Overture used to be a pretty good tool but has stopped working since a long time back. I have just put it for historical purpose as it was a nice friend back in 2006. Lot of Keyword Tools based on Overture like DigitalPoint Keyword Research Tool and Prioritysubmit tool have also stopped working (DP’s wordtracker tool is working though)
Well I have already spent lot of time in building this list so I won’t be updating the blog for next 2 Days 
since I have ran out of steam. I feels i should concentrate more on quality rather on Quantity and should Only update the blog in 2 days time with one Really good Post. So here is one good Post, if you liked it, a Thank you note will be appreciated.
Do spread the word about the list, bookmark it and link it If you know some more keyword research tools then do tell me as comments.
Cheers and Have a Nice Day
Pushkar
more info about the List Of Keyword Tools
