The Ultimate SEO Checklist: The 21 Most Important SEO Factors in 2021

Digital marketing - Search engine optimization

In this ultimate SEO checklist, you will find 21 SEO checks that ensure your website is better found in Google. Can you check them all off? Then your website is 100% SEO-proof!

The ultimate SEO checklist is a list of factors that can be divided into technical SEO optimizations, content-related factors, and your website’s hosting. 

The Ultimate SEO Checklist The 21 Most Important SEO Factors
Search Engine Optimization (SEO) Concept On Computer Screen

Of course, we could have mentioned more than 21 factors in this article, but the factors must demonstrably work. Of the factors on this checklist, Google has confirmed that the algorithm looks at them or has reputable SEO experts indicate that they are really effective.

Technical SEO optimization

Let’s start with technical SEO optimization. These are usually the areas for improvement that SEO experts look at first. In our view, these improvements should mainly be seen as basic requirements to ‘participate’ in the search results. These improvements are sometimes difficult to implement. If you cannot find a solution, ask your internet agency or hosting provider for help.

1 – Correct Page Titles

A very important factor.

(Perhaps the most important.)

The page title is the title of the page, and you will see it in the tab within your browser and shown as the title in the Google search results.

Why is this factor so important? Not only Google looks at the word usage in your page title. The visitor also determines based on your page title to click on your page in the search results. This ‘clicking’ determines whether you get visitors at all via Google. The indicator for this is called your CTR, the ‘Click Through Ratio.’

Each page has its own CTR, and the more people click on a page, the higher the CTR of that page. Google naturally likes to fill its search results with pages that people click on to have a high CTR.

2 – SEF URL structure

SEF stands for ‘Search Engine Friendly.’ In the early years of developing systems for publishing websites, a legible URL was not high on the list of priorities. This created URLs such as


Google cannot do much with this, and the result was that HTML websites without CMS scored better in the search results. Hence, almost all CMS nowadays have a method to change the internal URLs to SEF URLs.

The Ultimate SEO Checklist The 21 Most Important SEO Factors

In many cases, this SEF URL is built based on the title that you give to your page. Sometimes a category or tag is also added to this. And so you can get a page like: /articles /the-ultimate-SEO-checklist, while this page is actually called/node/23 internally for our CMS.

Besides the fact that the URL must be readable, the structure is also important. 

This allows Google to discover a structure within your website. It becomes clear that / articles / is an overview page for our articles where the URL starts with / articles / *. If you were to change the URL for all articles to / article / the-ultimate-SEO-checklist, this might be correct grammatically, but the structure would be lost.

3 – Use of H1, H2, H3 tags

Google uses the headings to determine what the content is about. The H1 tag is seen as a title and may only appear once. The H2, H3, etc. tags are seen as subtitles and can be used more freely. Although it is preferable to build it up logically.

4 – Responsive web design

A website with a responsive web design adjusts the website’s layout so that it is properly displayed in the visitor’s browser. Your web designer should have taken into account visitors from different devices and come up with different layouts for this. Because your website is optimized for visitors who Google via a smartphone or tablet thanks to a responsive web design, Google sends more of these visitors to your website. 

5 – XML Sitemap

By offering Google an overview of your website, Google will index it better. You can have this overview in XML format automatically generated by an XML sitemap plugin for your website. Then you must pass the URL of your sitemap to Google’s Search Console. 

6 – A fast and light website

Google has been trying to encourage us to speed up our website for years. Makes sense because one of Google’s highest costs is indexing all websites. If they become a fraction faster, Google will save a lot of money with this. Google’s promotion for the fast website started in the Search Console and later expanded with Google’s Pagespeed Insights.

The Ultimate SEO Checklist The 21 Most Important SEO Factors

You create a fast website by working with a hosting provider that invests in it and by optimizing your website. 

You can optimize your website by turning on your CMS’s cache system and using an optimization service such as

Another option is to make your website lighter. This involves the use of movies or images that are large or not properly compressed. The easiest way to fix this is to minimize image usage. 

Certain effects may also be achieved through CSS, which makes the website lighter. You can also increase the compression for your images or apply compression to your CSS and javascript files.

7 – HTTPS Secure connection

Offering your website via https is now a requirement for good findability. Especially because Google insists on offering safe websites for its users.

With services such as and, you can purchase an SSL for free and offer your website via https. Do you want to know more about this: How do you switch to HTTPS?

Substantive SEO optimization

Now that your website is optimal in terms of SEO technology and hosting, it is time for perhaps the SEO improvements that have been increasingly rewarded by Google in recent years. We are talking about the quality of your website and content. By offering a website that is pleasant to use and actually offers a solution for your visitor, you can make a distinction.

But how does Google know if your content is good? There are numerous indicators that Google can use to measure this. An important one is the bounce rate of your page. 

This is the percentage of people who go to the page after a search from Google and then go back to Google. This ‘bounce’ is a clear indication that the page does not provide an answer or solution to the question or problem the visitor has. 

The checks and points for improvement below will cost you relatively more time, but, on the other hand, have the potential to make your website stand out head and shoulders above the rest!

8 – Long pages

For years, there has been a clear correlation between longer pages and a high search results position.

one page website is good or bad for seo

It is not yet entirely clear why that is. Visitors may appreciate a lot of text because they can answer multiple questions with more information. It may also be that the longer pages ensure that Google measures that the visitors stay longer on the pages and uses this as an indication of good content. Another possibility is that a longer page contains more keywords and therefore attracts more visitors who use other keywords.

An optimal length of 2500 words for one page can be derived from various SEO studies. If you notice that your pages are stuck at 800 to 1000 words, you can consider merging them. In addition, you can provide additional explanations for parts that you name within your pages.

9 – Keyword usage

Sounds logical, but it is not the case that if you only place a certain keyword in your text 20x, you will automatically be found correctly. By keyword use, we mean a natural structure of your keywords. You think about related keywords and use them in places outside of your normal text. Think of the alt text of an image, a category, a tag, or a link.

10 – Call-to-actions

A call-to-action is a button on a page that clearly asks the visitor for action: ‘sign up,’ ‘order our brochure,’ or ‘do you want to learn more?’. These are all calls-to-action, and they take care of a number of things. 

  1. You write the page with a purpose. 
  2. The visitor knows what your goal is. (And therefore also test the content with this goal in mind.) 
  3. Your visitor will not click around aimlessly and is more likely to go to the next step.

One of the positive effects of call-to-actions is that they cause a ‘click’ to the next page and thus help the bounce rate down.

11 – Current content

This has been a known factor for a higher ranking for years. People who search often want the most up-to-date result possible. It is therefore advisable to update your content every now and then and see if it still applies.

You can also show user-generated content such as reviews, comments, or questions from visitors on your pages. This ensures that the pages are up to date for Google again. It is important that Google can index the user-generated content. Comments via Facebook or Disqus are not seen as part of the content because it is loaded from an external platform.

Futurumshop answers customer questions on their website. This continuously creates current content.

12 – Strong titles

A good title is used by many CMSs to build the URL, the page title, and the H1. As you may have read in the above SEO checks, these are extremely important. In addition to placement in the search results, a strong title also ensures a click from the visitor. 

This increases the CTR (Click Through Rate), which in turn increases the place in the rankings. When coming up with your title, you should think carefully about adding essential keywords and convincing the visitor to click on your page instead of the competition.

But don’t I make clickbait  titles? With clickbait, you make the title overly sensational. At the same time, you do not live up to this with the visitor’s content. This works especially well on social media because Google also looks at what happens after the click. Want more help here in creating strong titles? Read also: 8 tips for the perfect titles.

13 – No broken links

Links to internal or external URLs that no longer work are called ‘broken links.’ Whether these are bad for findability is not proven. Still, many SEO experts agree that there is a very good chance that broken links will have a bad influence on your website’s reputation.

Try to prevent them by structuring your internal links properly, using a plugin or module that automatically creates the links. Do you want to check if your website has broken links? Then visit

14 – Inbound links

These are links from external websites to your website. This was a very important factor in the early days of Google. The so-called page rank that a page received was calculated based on the pages’ rank linked to it. Before long, you were able to buy links to your pages, thus crumbling the value of this system. 

While PageRank is a thing of the past, inbound, or backlinks as they are sometimes called, remains an important factor.

How do you get inbound links? Create content that is interesting to link to. This is particularly interesting if the content remains good for a longer period. An investigation, a comparison, or a handy checklist…

Of course, funny or challenging content scores better on social media. Still, the number of visitors and the impact this has on your SEO is temporary.

15 – Qualitative outbound links

These are links on your pages to external websites. Don’t be too conservative with this. I often hear from our clients that they prefer not to place them for fear of losing the visitor. Of course, that can happen, but be aware that it can always happen. On the internet, the visitor is in control, and you will have to convince them. One of those ways is to enrich your content with links to sources that confirm your claims or content.

Take a good look at the quality of the website you are linking to. Chances are that Google will rate your website higher if the links you place go to high-quality websites.

16 – Enough Internal links

These are important because you draw the visitor’s attention to other content within your website. If a visitor clicks on this, this is not only good because they read more content from you, you also let Google know through the click that the visitor makes. User metrics such as the bounce rate are lowered by the initial internal link page.

17 – Remove duplicate content

Duplicate content is not directly harmful to the findability of your website. It indirectly ensures that there is less unique content on your website, which does not promote findability.

So try to avoid duplicate content where possible. This can be done by taking a critical look at your texts and making them as unique as possible. Duplicate content often arises on overview pages for services, products, events, or articles.

In many cases, Google will not rate these overview pages highly in the search results because the content that is displayed is often already used on the final pages of the services, products, events, or articles. In itself, this is not a disaster as long as you understand that these pages will not be entry pages for a large number of your visitors.

Do you want to know more about duplicate content? Also, read: Is duplicate content harmful?

18 – Alt Texts

The alt text is a text that was previously displayed when a picture was loaded. Now the alt text is used by screen readers. These are browsers that read it out to you instead of showing your website. For example, people who are blind or partially sighted can visit websites. If we do not enter alt text, the screen reader will read the image’s file name. Very nice if that is DCM_87976879_2020.jpg.

Search engines use alt text in two ways. They create a database of images (think of Google images). They learn more about the context of the image on your website.

So do yourself, visually impaired and blind people a favor and always fill in the alt text. You can simply describe what is shown in the image.

19 – Clear web design

Good web design does not immediately lead to a jump in your position in the search results. But it has an impact on various factors, each of which determines your position. Research shows that a clear web design that is easy to read ensures a website that visitors have more confidence in and stay longer viewing the content. Do you want to read more about this? Read also: Does good web design improve SEO?

20 – Contact information

For Google, it is difficult to verify whether the displayed content comes from a reliable source. One of the ways to confirm this is to look at a physical address on the website. Shady websites generally do not place them, so you can easily filter them out., a well-known website for SEO experts, concludes:

In conclusion, putting a verifiable real-world address on your website appears to increase its chances of looking more algorithmically trustworthy to Google.

Tip: Place your address in the footer of your website. This is how it is shown on every page. Good for your findability and practical for your visitors.

21 – Make sure your spelling is correct

Google understands our language better and better and can trace errors. You will notice that if you have worked with Google Docs in recent years. The spell checker keeps getting better.

It is not 100% certain that Google will degrade your position if you make too many spelling mistakes, but Bing (that other search engine) stated in 2014 that it will. 

I would therefore err on the side of caution and check the spelling of your texts carefully. If only because it makes a better impression on your visitors.


That was it, the ultimate SEO checklist. Hopefully, you have been able to improve your website on several points with this list. Do you have any questions about one of the SEO checks? Then you can ask this via the response section at the bottom of this page.

The ultimate SEO checklist is a list of factors that can be divided into technical SEO optimizations, content-related factors, and your website’s hosting. Of course, we could have mentioned more than 21 factors in this article, but the factors must demonstrably work. 

Of the factors on this checklist, Google has confirmed that the algorithm looks at them or has reputable SEO experts indicate that they are really effective.

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