Backlink Investigation

1. Open Site Explorer: http://q.gs/7b0Nq
2. Majestic SEO Site Explorer: http://q.gs/7b0Nr
3. Ahrefs Site Explorer: http://q.gs/7b0Ns
4. Link Diagnosis: http://q.gs/7b0Nt

Server Investigation

1. BuiltWith: http://q.gs/7b0Nu
2. Pingdom Full Page Test: http://q.gs/7b0Nv
3. Google PageSpeed: http://q.gs/7b0Nw
4. URI Valet: http://q.gs/7b0Nx
5. SpyOnWeb: http://q.gs/7b0Ny

Website Crawling & Link Checking

1. Screaming Frog SEO Spider Tool: http://q.gs/7b0Nz
2. Xenu’s Link Sleuth: http://q.gs/7b0O0
3. W3C Link Checker: http://q.gs/7b0O1

Content & Markup Analysis

1. SEO Browser: http://q.gs/7b0O2
2. Copyscape: http://q.gs/7b0O3
3. W3C Markup Validation Service: http://q.gs/7b0O4

Keyword Research

1. Google AdWords Keyword Tool: http://q.gs/7b0O5
2. Wordtracker: http://q.gs/7b0O6
3. Ubersuggest: http://q.gs/7b0O7
4. Latent Dirichlet Allocation Content Optimizer: http://q.gs/7b0O8

Competitive Keyword Analysis

1. SpyFu: http://q.gs/7b0O9
2. SEMRush: http://q.gs/7b0OA

Social Discovery

1. Shared Count: http://q.gs/7b0OB
2. SocialMention: http://q.gs/7b0OC
3. Follower Wonk: http://q.gs/7b0OD

PR & Outreach

1. HARO – Help a Reporter Out: http://q.gs/7b0OE
2. Blogger LinkUp: http://q.gs/7b0OF
3. MyBlogGuest: http://q.gs/7b0OG
4. DoubleClick Ad Planner: http://q.gs/7b0OH

Analytics

1. Google Analytics: http://q.gs/7b0OI
2. Open Web Analytics: http://q.gs/7b0OJ
3. Piwik: http://q.gs/7b0OK

Search Engine Guidance

1. Google Webmaster Tools: http://q.gs/7b0OL
2. Bing Webmaster Tools: http://q.gs/7b0OM

SEO Analysis

1. WooRank: http://q.gs/7b0ON
2. Lipperhey: http://q.gs/7b0OO
3. Pearanalytics: http://q.gs/7b0OP