Frequently-Asked Questions

Prerendering is a complex subject, and it’s not always easy to understand its importance for an enterprise website or single-page application’s organic success. But after years of working with clients of every size—and in every industry—we’ve decided to compile the most common questions in one place. Pin this as your hub for all things dynamic rendering.

All Your FAQs Answered!

Find out more about Prerender, technical SEO, JavaScript, and more.

When you click on a website, your browser sends a request to the site’s server to retrieve (fetch) the necessary files (like HTML, CSS, JavaScript, images, etc.). This is used to build the final visual representation of the page (rendering), and it takes place every time you navigate to a page. Now, to speed up the process, we can render the page ahead of time. How, you might ask? We send a pre-rendered static HTML version of the page to the client, providing a faster and more seamless experience to the user or search engine.

We use a technique called dynamic rendering, which can be considered an advanced version of prerendering. Prerender fetches all the necessary resources to build your pages and caches a pre-rendered version of them.

When a new request is sent to your page, Prerender’s middleware will determine whether it’s a search bot or a human user asking for your page: if it’s a search crawler like Googlebot, it’ll send the cached version to make it easier for search engines to crawl and index its content. If it’s a human user, they will get redirected through your normal server routes solving all JavaScript-related SEO issues and allowing you to provide an immersive, JavaScript-rich experience to customers. Learn the full details of Prerender’s process.

There are three major reasons to optimize the rendering of your JS site:

1. Search engines can’t handle JavaScript content correctly – in most cases, search engines take 9x longer to crawl and index JS-based pages than regular HTML sites. This leads to a lot of issues like missing content, limited crawl budgets, and lower rankings. By prerendering your pages, you’ll solve all JS SEO issues from its root.

2. PageSpeed impacts your rankings – unresponsive, slow pages are frustrating for everyone, including search bots, and JavaScript has the biggest impact in loading times. To increase your site’s chances of getting into the first spots in search results, your pages need to load in 1 – 2 seconds or less. Prerender nails this by delivering your pages in 0,03 seconds on average.

3. Most rendering solutions are expensive, hard to implement, and have negative effects that are difficult to work around – traditional solutions like server-side rendering require a minimum of $100k in upfront investment to cover server equipment, software infrastructure, and engineering time, and still have a negative impact on your site’s time to first byte (TTFB) and first input delay (FID).

In contrast, Prerender takes just a couple of hours to install and test and will get you near-perfect SEO scores for a fraction of the cost and with none of the drawbacks.

The short answer is yes, but indirectly. Prerender is designed to help solve all JavaScript-related issues for enterprise and single-page application sites.

This means your pages will get higher performance scores (which is a confirmed ranking factor), increase crawl budget and speed up the indexing and re-indexing of your website. These benefits alone can take you further on your SEO journey than any manual workarounds.

However, your site’s rankings are determined by a plethora of factors like content and backlinks. Prerender will give you a solid foundation for your SEO campaign by handling the challenges of JavaScript optimization, allowing you to focus on other essential factors.

Usually, this question comes from developers and business owners worried about cloaking penalizations. Let us reassure you that there’s no risk at all. In fact, Prerender has been the recommended choice by Google to implement dynamic rendering since 2018.

Prerender does not change any content on your page. It just renders the HTML file and all resources and delivers the result to Google – users and Googlebot will receive the same content.

On the other hand, cloaking is about misleading Google to index a page for irrelevant keywords by serving crawlers one type of content and providing people with a totally different page when they click the link in search results.

By default, Prerender can recognize the following bots:

prerender.crawlerUserAgents = [
‘Yahoo! Slurp’,
‘quora link preview’,
‘Google Page Speed’,
‘Bitrix link preview’,

Learn how to add additional bots to the list.


No matter what JavaScript framework or technologies your backend was built with, Prerender integrates with any modern tech stack. You won’t have to rewrite your code or change anything from your setup.

For a full list of Prerender integrations, visit our documentation. 

To integrate Prerender with a Bubble.io app, you’ll need a custom plan that includes a dedicated server so you’re able to install our middleware.
Standard plans won’t be able to integrate with Prerender.

On average, Prerender takes 2 to 4 hours to install and test to ensure everything is working properly. It doesn’t require extensive knowledge, and our team will support you every step of the way if needed. Find the installation instructions based on your tech stack.

Unlike other JS solutions, Prerender doesn’t render your page – necessarily – every time a crawler requests it. Instead, it renders and stores your pages in its cache to be delivered at the moment the request comes in.

This process occurs in two scenarios:

1.) The first time Prerender finds a URL in your submitted sitemap or the first time a crawler requests a page that hasn’t been cached yet. 2.) After the time set expires, Prerender will recache your page to update the current version and pick on any changes and improvements made to it. Every caching task consumes one cache/recache included in your monthly plan.

Taking advantage of the rendering process, Prerender scores your page’s technical optimization and allows you to detect optimization opportunities or technical SEO issues that can affect your site’s SEO performance.

You’ll also be able to monitor metrics like Prerender’s time to fully load your pages, which can be a great benchmark to understand how the end user (aka your customers) will experience your site and optimize it accordingly.

The best part of using Prerender is that it is an automated process. Although you can submit a sitemap to speed up the rendering process of critical URLs, the Prerender’s middleware installed on your back will detect any request coming from a recognized crawler and generate a cached version for every URL requested without needing further configuration.

That way, the service will scale as your site scales automatically – which is ideal when, for example, you can’t predict all URLs in advance.

We count every time a page is rendered, and this happens every time you cache a new page (or recache) an existing one. We recache pages automatically, at the frequency set in your “Cache Manager” under “Cache Expiration.” You can also recache pages ad-hoc via our API.

Pages are rendered differently for desktop and mobile, so each version counts as a render. For example: if you have 1,000 URLs being rendered daily, we will count 60,000 renders per month: 30,000 for desktop and 30,000 for mobile.

Want to Learn More About JavaScript SEO?

Understanding how JS impacts your SEO is vital to start fixing issues holding your site back. Explore everything SEO in our blog and become the expert you’re meant to be. See you in the SERPs!

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Prerender currently serves 2.7 billion web pages to crawlers.
Trusted by 65K businesses across the globe.