As SEO becomes an increasingly important part of web development, it's important to make sure your website conforms to the correct standards to help improve your search ranking. This is an area where you should be willing to spend some money, as the results are often well worth it in terms of increased traffic and customer conversions.
There are a lot of tools out there to help you identify your SEO strengths and weaknesses, from services that monitor your keyword rankings on popular search engines (SERP, or Search Engine Results Page) to more complete, premium solutions that tell you exactly what you should change to make your site rank better.
DIYSEO claims to be a "web-based solution for small businesses to get search engine traffic at a fraction of the cost." It's basically a tool that allows you to coordinate and plan your SEO strategy, act on it based on their suggestions and finally measure and analyze the results. It costs either $49/mo or $499/yr if paid in advance, both options with a 7-day free trial.
GinzaMetrics is a new YC-backed company that allows you to "monitor search engine rankings, track conversions and improve your SEO." It's geared towards larger companies and agencies by providing enterprise-grade SEO/SEM solutions. Prices vary depending on the amount of keywords you need to use, ranging from a free plan to $999/mo for their most expensive option.
SheerSEO is an SEO software to track and analyze your SEO campaign that also helps you with link building. This is one of the more feature-rich applications that tracks a load of information, from keywords to rankings to social media relevance. It's a powerful tool that's priced pretty reasonably, with plans starting at $7/mo and going up to $199/mo for agencies.
SEO Rank Monitor is all about tracking keywords - how your website ranks for multiple keywords, how your competitors rank and understanding organic search growth. They offer two plans, a basic that tracks 1 website and 100 keywords ($19/mo) and a pro plan that tracks 10 websites and up to 2500 keywords ($39/mo).
Another SERP/keyword monitoring service similar to SEO Rank Monitor but even simpler (more bare-bones). Their pricing is also similar however they seem to offer a better bang for the buck in terms of number of sites you can watch, and they even have a live demo which is nice.
I've been playing with this site for the past couple of days but I'm already a fan - you can test it out by going to their site and entering any domain name to find how that site ranks for many keywords. It's highly useful for finding relevant keywords to build on, however they limit the free results to the top 10 keywords. Their premium plans start at $59/mo and allow up to 10,000 results per report, plus they give you API access, which is very cool.
Raven Tools is another full-fledged SEO service that helps you monitor keywords, social media buzz and even integrates with Google Analytics to generate custom reports based on your traffic. Their base plan starts at $19/mo and provides 100 keyword ranking results, however all plans come with a 30-day trial.
The guys (and gals) at SEOMoz have created a number of free and paid tools that help you view backlinks, identify keywords and a "geotargeting detector" that tells you how well your website is targeted towards a certain geographic area.
SEORush provides a quick overview of how well your site is indexed, traffic rankings and the number of social media bookmarks it has for a few popular networks. I would suggest using this tool together with something like QuarkBase to get a quick overview of the popularity of a site, and to get some quick ideas for keyword generation.
Keyword Envy is just a quick and dirty tool to check how a website ranks for up to 5 keywords on several search engines. They also offer paid plans that offer more keywords and a few additional features.
Do you have any other tools you use to monitor and check the SEO status of your websites? If so suggest them in the comments and I'll add them to the list!