How to make your JavaScript apps SEO-friendly

One of the challenges in moving your application logic from the backend (Rails, Django or whatsoever) to the new frontier of JS web frameworks like AngularJS and EmberJS is how you can make them SEO-friendly, as these JavaScript applications get sent to the browser by your webserver as a 200 OK, no matter if, once the app boots, the page that its being represented is not found, or has some specific metatags, like title and description.

This is, for example, how a tipical angular app’s HEAD section of the HTML looks like:

    <meta charset="utf-8">
      {{ pageTitle }}
    <meta name="keywords" content="{{ metaKeywords }}">
    <meta name="description" content="{{ metaDescription }}">
    <link type="image/x-icon" data-ng-href="" rel="shortcut icon">
    <link rel="stylesheet" href="">

As you see, the page title, which is what SE like Google use as main text in your indexed pages, is a mere placeholder for a variable that come after the JS framework has booted and executed its own logic, eventually leading to SERP results like this:

So, how will you make sure that search engines will actually see the post-processed HTML and not the very first one that gets sent from your server?

You have at least a couple different solutions that use the same underlying tecnique.

Once feared, Cloaking is your only way

The practice of cloaking has been penalized by search engines for years but turned out to be endorsed by Google when you have JS-based apps.

It basically consist in serving to the search engine a different version of the webpage, already rendered, instead of the one that you would serve to a normal visitor, which has to run the JS framework on the browser.

The workflow is very simple: instead of serving, from the webserver, your traditional app that you would serve to a normal user, in case of a bot you simply forward the request to another application, which will request the original page, wait for it to render through an headless browser like PhantomJS and then serve back the fully rendered content to the bot:

This is a very straightforward way to effectively implement SEO in JS apps, and it can be achieved with a couple tools instead of having to write the whole thing on your own.


BromBone is a service that crawls your sitemap, generates a snapshot of the rendered HTML, stores it on Amazon (presumably S3) and relieves you from the pain of setting up the middleware SEO app on your own.

It basically acts as the SEO app seen in the picture, but instead of rendering pages on the fly it does it by looking at your sitemap: once the bot hits the webserver, you can then proxy it to the BromBone page so that it gets the actual response from the server.

Even though the service is very affordable relying on the sitemap it’s a bit tricky, because, well…what happens if you have new pages that are not included in the sitemap?

After bumping into this requirement we, at Namshi, decided to opt for something else.


Prerender is both a SaaS and an open source library that prerendrs pages on the fly using PhantomJS and some other nice tricks to serve the correct status codes and HTTP headers.

The only disadvantage with rendering on the fly is that the bot will have to wait a bit longer in order to get the response, and this might result in a penalization from search engines: the solution is very simple, as you can simply warm up prerender’s cache on your own by hitting the URLs that you want to cache. In order to refresh the cache, Prerender lets you do POST requests, so that:

Prerender gives you a bit more freedom compared to Brombone but it requires you to do some manual work, at least if you want to run it on your own servers without using their solution as a SaaS; in any case, their pricing modes is very affordable as well.

What shall I use?

It really depends, as both are very interesting tools: given our confidence with NodeJS and the will of developing some of the SEO-related stuff in-house, so that we have a bit more control over these things, we opted to give Prerender a go, but if you feel the sitemap solution proposed by BromBone is good enough for you, I’d recommend you that service, as it’s easier to run and requires very less configuration / manual work.

All in all, the good thing is that, in 2014, we can finally say that making SEO-friendly JavaScript apps is not a hassle anymore!

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