Are Site-Wide External Header and Footer Links Bad for SEO?
Every website has two types of content on each page: the unique content and the site-wide content. Site-wide content is essential for good website design and navigation flow, but with it comes a question: are the links in those places good or bad for SEO?
First, Some Examples
Site-wide content can vary a lot. Let's look at some examples.
NeilPatel.com has a top bar banner, a top navigation bar with links to the homepage/blog/pricing/training/tools/etc major content categories, and nothing else at the top. To the left, there's nothing, but to the right are a few persistent CTAs. One is an easy sign-up with a box to plug in your website URL. One is a picture of Neil with his About description; basically, the author bio box placed to the side rather than the top or the bottom. One is the search bar, and another is another CTA. Then you have links to his major guides, like the Digital Marketing guide, the SEO guide, and his Affiliate Marketing guide. He also has links to tools, another CTA for his service, and the ever-present social sharing buttons.
SEORoundtable is somewhat similar, but with more ads. Across the top, they have a variety of site links, an advertising banner, the search bar, and the categories. Along the side, they have a few CTAs, some video links, and browse links. Down in the footer is, again, links similar to what's all the way up top.
However, there's one thing you see on SEO Roundtable that you don't see on Neil's site: links to other sites. In particular, they have links to three sites: Rusty Brick, Creative Commons, and YouTube.
This is where the question arises: do those links count for SEO, and do they do it in a positive way or a negative way?
Intuition and Inference
If you're a seasoned SEO professional or a novice marketer with a little knowledge of how links work, you're probably immediately skeptical of these kinds of links. You might, however, intuit that they can't be too terrible, because they're pretty common.
The way links work, any time you link to a site from your site, that destination site gains a little bit of your SEO value. Conversely, any site that links to you gives you a bit of their SEO value. This "link juice" is the core of how Google's algorithm analyzes the web and ranks sites, though there are well over 200 other factors that contribute to this algorithm.
Influence is proportional to the existing value of the site. A small, brand new blog isn't going to give much value to any site it links to. A huge site like Forbes is going to give a ton of value to any site it links to.
There are exceptions, of course: a site like Facebook or Wikipedia isn't going to pass much value with links, because users can create those links. You can just go make a Wikipedia account and link to your own site in various pages. Sure, it's against Wiki rules and those links may be removed, but any that survive would be very valuable. Wikipedia cuts down on value so they aren't constantly spammed. Facebook doesn't care, but also doesn't pass much value, in Google's algorithm.
The exception to the exception is when the site links to the pages in an authoritative way. Facebook won't give you much value if it's just some user's post linking to you, but it will give you a lot if it's part of the Facebook Newsroom linking to you.
All this is to say that big sites don't have to worry about site-wide links, either positively or negatively. Like many aspects of SEO, they're simply too big to have to care about it. Using something like Facebook as an example won't do much. The same goes for the SEORoundtable links to sites like Creative Commons and YouTube. Neither of those sites is small enough for those links to matter one way or the other.
Where Google is more likely to take exception is when the sites involved are small or mid-sized blogs. Small blogs that add a link to another small blog indicates that the blog is providing a large vote of confidence to that other site. When the link is site-wide, it feels more like the linking blog is doing it to dump all their link juice on the other site.
This is bad in part because it has been used as a spam technique in the past. It has been used willingly as part of link wheels and private blog networks. It has also been used unwillingly, when hackers would compromise a site but do nothing other than adding their link to site-wide navigation, often hidden in a way that makes it give SEO value without being visible to users. These are both spam and both will give the linking site a search penalty.
What Google Says
Now let's add a bit of critical thinking to the situation. Site-wide links are easy to set up and feel like a good idea. If you have a partner site, you want people to know that the partner site exists, so you add it to your site-wide links on a sidebar or in the footer. Google knows that this is a common technique, and they also know that footers are often used to give credit to site designers and architects, platform hosts, or what have you. Every WordPress site that has a "site hosted by WordPress.com" or a "theme by X" link at the bottom would be hurting itself if these links caused a negative SEO penalty.
Thus, Google must make an exception for these kinds of links. And, indeed, they do… somewhat. Here's what Google has to say, at least as of a couple of years ago.
"Sitewide header and footer links are not a very great weight in general." - Source
Google knows that those links exist, and they know that sometimes they're part of site structure, and sometimes they're part of webmaster-added advertising. As such, they dialed back their value – both positive and negative – way down low.
The links are not completely worthless. They still pass some link juice. However, that link juice is usually just a very small positive boost. It's only when there are confounding factors, like the relative value of the sites, that it can be twisted into a negative.
If your site has a "powered by WordPress" or "powered by phpBB" or whatever link at the bottom of it, that link isn't going to hurt you one way or the other. You're linking to a huge, trusted name. Google and users can rest assured that the destination on the other end is safe and that the link isn't there as part of some kind of spam campaign. This is broadly true of every "credit to the designer" style link, though some may have less value than others.
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On the other hand, if you have a "friends of the site" box on the side and just link to a bunch of other sites? That can be less useful. A big name example of this would be the whole formerly Gawker set of sites, like AV Club, Deadspin, Jalopnik, and Kotaku. All of these sites have a site-wide banner that links to each other.
If you tried to do this as a small site, chances are you'd be penalized for it. On the other hand, since they're large and relatively trusted blogs, they can link together without issues. It's also important to note that all of these sites are part of the same network, and they readily acknowledge that they're all owned and operated by the same entity. If small blogs tried this and tried to hide it, it would be much worse, but being upfront about it might make it closer to alright.
A History of Abuse
One of the reasons these links are generally low value or even ignored is that, in the past, they were abused. Here's something you might never have thought of, but which happened years ago.
Every WordPress-powered site that doesn't have a custom design uses a theme. Those themes almost always have a credit to the author of the theme down at the bottom, right? For example, one of the themes by ElegantThemes in a live demo, if you scroll all the way down, you see "Designed by Elegant Themes, Powered by WordPress", with both Elegant Themes and WordPress linked.
Years ago, a designer could design a theme with the sole intention of selling permanent sponsored links in the footer, and auction them off to the highest bidder. Person A would pay Person B to design a theme for Person C to use. Person C uses the theme, and that theme now has links at the bottom to Person A and Person B. Anybody that installs this new theme will install it with a sitewide backlink to your site in the footer, and many of these links were either complicated (or impossible) to remove.
That alone isn't bad, but if hundreds or thousands of people use the theme, that's thousands of links to both the designer and the sponsor. That sponsor did nothing other than pay a fee to the designer to design it. For a one-time fee, they get as many links as there are people using the theme.
The sponsor here didn't really contribute much. In fact, you might argue that all they're doing is paying for a ton of links they didn't earn. And, indeed, that was the problem and is why Google decided to penalize it.
The NoFollow Solution
The primary solution to most link-based SEO puzzles is simply going to be liberal usage of the
In SEO, the nofollow attribute is a piece of metadata attached to links, and all it says is "Hey Google, we know this link isn't great, please don't count it against us." It does still kind of count against you, in that it still divides up the outgoing link juice, it's just that the link juice flowing to it goes nowhere. Here, an example:
Page 1 links to Page A, Page B, and Page C. 33% of link juice flows to A, to B, and to C. If all three are followed links, all three get 33% of the link juice and the corresponding boost to SEO.
If you determine that Page C is low quality and you don't want it getting your link juice, you can nofollow it. The result is that your page links to pages A, B, and C. A and B both get 33% of your link juice, and C gets nothing. The remaining 33% of the link juice just goes nowhere.
If this sounds like a waste, well, it kind of is, and it's a discouragement from linking to sites that aren't worth it even if you use nofollow. It's also a discouragement to keep people from sculpting their SEO flow. You can look up "pagerank sculpting" for more information on that.
Nofollowing links is still a good idea because it generally allows Google to not penalize you for something they might have penalized you for, had you left the links alone. It's not necessarily better than removing the links outright, and it won't protect you from link spam that affects your users, but those are special cases.
All of that is theory: how can you determine if your links are fine, if they're bad, or if they might become bad, and what can you do about it, in practice?
Determine if the link is essential. Some site-wide links are essential, in that they're legally mandated to be there. Usually, this is a "credits" link for a platform or designer. WordPress having the "powered by WordPress" link, a site theme mandating their credit like "powered by Elegant Themes", and occasionally links added by a web host or domain registrar all count for this. If you use the service you need to follow the service's rules, and if those rules say not to remove the link, don't remove the link.
Now, one thing to mention here is that links from web hosts or registrars are, usually, considered part of the "spammy free host" SEO attribute and can penalize your site. Free web hosts used to do this to get free advertising, but it's now penalized and it's rare to find a host that still does it.
If the link is essential, keep it there. Chances are it's nofollowed by default anyway, and it won't hurt you.
Determine if the link is valuable. The second judgment you need to make is whether or not the link is important enough to keep its position. Links to off-site CTAs, links to networked sites, and other links that are valuable for the business or for the user are often fine, though they might need to be nofollowed. Links to random "friends of the site" are much less valuable to both Google and the user, and should definitely be nofollowed, if not removed entirely. Remember: the more value it has to a user, the more likely it is to be safe.
Determine the relative quality of the destination site. Is the link pointing at a big site, a medium site, a small site, or a brand new site? The larger the site on the other end, the more likely it is that it's safe. Links to WordPress, to YouTube in general, to other site design companies, these tend to be fine. Links to your friend's site, much less so. In general, of course, those links should be nofollowed on principle regardless.
Consider setting open in new window functionality. One way that these site links can hurt you is through your increased bounce rate. If a user lands on your page and decides they want to click a link in your header, that link can lead them away and is basically a bounce for your site. By making it open in a new window or tab (using
target="_blank") can help with this problem by keeping the window with your site open.
Aggressively nofollow. When in doubt, nofollow the link. 90% of the problem can be alleviated by nofollowing any link you're even partially skeptical of. Google isn't going to penalize you unless you're being aggressively terrible anyways, so just nofollow links you aren't sure are fine and focus on user value. You'll be fine.