Below is an outline of the SEO services and tools in the digital marketing tools index.

Click on the link below each section for a page with more detail.

SEO Tool Suites

SEO PowerSuite – free version with basic features (desktop software).
WebCEO – free version with limitations.
Moz – 30 day free trial.
SISTRIX – 14 day free trial.
Analytics SEO – free account with basic features.
Rank Ranger – 30 day free trial.
RankWatch – 14 day free trial.
SEO SiteCheckup – free trial (how long?)
Lipperhey – free plan with limited features.
Traffic Travis – free edition with lower limits and less functionality.

SEO Rank Checkers

Authority Labs – 30 day free trial, no credit card required.
SEMrush – 7 day money back guarantee.
Web CEO – Free plan includes basic features and low limits. Might be useful as a trial.
Positionly – 14 day free trial.
Advanced Web Ranking – 30 day free trial for cloud-based version.
Moz – 30 day free trial.
Cognitive SEO – 14 day free trial.
SerpBook – 30 day free trial, no credit card required.
SERPS.com – 30 day free trial, no credit card required.

Keyword Research

Google AdWords Keyword Planner – Free – Requires signup to Google AdWords. Uses Google’s immense search query data.
Bing Keyword Research – Free – Requires signup to Bing Webmaster Tools. Another primary source of search query data.
KeywordSpy – $$ – Spy on competitors, PPC and organic. Also spy on top affiliates and their top products.
HitTail – $ – Claims to get back some of the “not provided” keyword data. Also, suggests under-performing keywords to target for new posts, pages or campaigns.
Wordtracker – $$ – Shows up to 2,000 keywords in a single search. Uses “KEI (Keyword Effectiveness Index)” to measure higher volume / lower competition keywords.
SpyFu – $$ – Spy on competitors. See which keywords they are using for SEO and PPC, estimated AdWords spending, much more.
keywordtool.io – $$ – Claims to reveal keywords Google’s tool hides. Free version: up to 750+ KW suggestions per search. Pro Plus version: search volume, CPC, competition, 2x more keywords.
Übersuggest – Free – Enter keyword(s) and see “auto-suggest” results on Google, Yahoo, Bing, YouTube, and more.
Soovle – Free – Enter keyword(s) and see “auto-suggest” results for that term + the first character of the next word.
WordStream’s Keyword Tool – $$$ – Claims to offer diversified long-tail keyword data. 30 free searches.

Link Building

Open Site Explorer (Moz) – open site explorer (link tool), plus analytics, rank tracker, keyword difficulty, crawl test, on page grader, more. 30 day free trial.
Ahrefs – Tools include site explorer, position explorer & tracker, content explorer, crawl report, more. 14 day free trial.
Majestic – Claims to have the largest link index database.
Monitor Backlinks – Check your bad links and your competitor’s good links. 30 day free trial.
Remove’em – Bad backlink removal. Self-service tool or full-service help.

Local SEO

BrightLocal – 30 day free trial, no credit card required. Suite of local search tools: citation tracker, local search rank racker, google+ local wizard, review site tracking, more.
GeoRanker – Discover top local citation sources + track local rankings.
Whitespark – Local citation finder + local rank tracker, sold separately.
Moz Local – local listing distribution (management, reporting, more), with search insights available as an add-on.
Google My Business – Free. Fill out your Google business listing(s) to be found easier on local search.
Yoast Local SEO Plugin – WordPress plugin makes it easier to format local data in a clear and uniform way. Also includes store-locator functionality.

Technical SEO

Google Webmasters Search Console – Free. Signup is a standard “must do” task for every website.
Bing Webmaster Tools – Free. Signup and learn what is there, and be ready for when new features arrive.
Screaming Frog – Desktop website spidering software. Free basic version up to 500 URLs. Unlimited paid version.
XML-Sitemaps.com – Online service crawls your site to build its XML sitemap. Free version up to 500 URLs.

Misc.

Google Algorithm Change History – updated list of known Google updates, curated by Moz.
SEO Tripwire – monitors your pages (or competitors) and emails if a change is detected.
WikiGrabber – find Wikipedia pages that need citations and dead link replacement.

Courses & Education

MarketingProfs University – search marketing school.
Udemy – search engine optimization certification courses (various).
Market Motive – search engine optimization certification course.
Online Marketing Institute – search engine marketing courses.
eMarketing Association – eMA’s Advanced Search Marketing Online eCourse.

Forums & Hangouts

/r/SEO/ – largest SEO subreddit at Reddit.
/r/bigSEO/ – another large SEO subreddit at Reddit.
Quora: SEO – the main SEO topic at this large Q&A site.
#SEOchat – Twitter chat about SEO, every Thursday at 1 PM EST. [archive]

Podcasts

SEO Rockstars – weekly, three co-hosts discuss the latest news in SEO.
SEO 101 – once every 1-2 weeks, aims to teach you SEO from square one.
Edge of the Web – interviews and tips on SEO and website issues.
eWebResults – weekly, co-hosts explain common SEO topics.

Blogs

Google Webmaster Central Blog – announcements highly relevant to SEO.
Google Official Blog – Google’s main blog, sometimes relevant to SEO.
Search Engine Land – leading source for SEO and digital marketing.
Search Engine Watch – covers SEO and digital marketing.
Search Engine Journal – search engine news and how-to guides.
Backlinko – in-depth SEO-related posts from Brian Dean.
Moz – research, how-tos, insights on SEO and digital marketing.
HubSpot – the SEO category of the popular HubSpot blog.
SEMRush – SEO and SEM advice.
Portent – tips on SEO, PPC, more.
SEOBook – sporadic posts, in-depth, often contrarian.

YouTube Channels

Google Webmasters – SEO information straight from the source, the Googlers.
Moz – in-depth SEO whiteboard videos, presentations from MozCon, and more.
Search Engine Journal – includes interviews from conferences, replays of webinars.
Koozai – whiteboard videos about SEO, PPC, branding, social networks and more.
Melbourne IT Services – covers SEO, web video, outsourcing, and business building.

Conferences

SMX (Search Marketing Expo) – many events in the US, Europe and Israel.
Pubcon (SEO & Digital Marketing) – events in Las Vegas, Austin and South Florida.
SearchLove (by Distilled) – several locations in the US and Europe.
International Search Conference – several locations in the US and Europe.
Ungagged – unfiltered events in Las Vegas (US) and London (UK).
brightonSEO – large event held in Brighton, UK.
SearchFest – yearly event held in Portland, OR, USA.
MnSearch Summit – event held in Minneapolis, MN, USA.
Search Insiders Summit – event held in Key Largo, FL, USA.
Search Marketing Summit Australia – event held in Sydney, Australia.
Connect by Search Engine Watch – brand being phased out for ClickZ Live.

more detail: Digital Marketing Conference Calendar