Inline ‑ Critical CSS

Speed up your online store by generating critical css

by Speed Boostr · Launched: March 2021

2.4 (5) on Shopify Built for Shopify

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Inline your Critical CSS to eliminate render-blocking resources. This will speed up your store.

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About Inline ‑ Critical CSS

With Critical CSS, the visitor gets the base styling as quickly as possible; because it’s right there in a <style> element in the document’s <head>, there’s: no extra request to the server for the stylesheet & no waiting for the requested styles to load in and render.The below-the-fold, or non-critical, styling is then loaded in the background to avoid render-blocking. Your website will load faster, especially for first time users. A faster load time will increase your conversation rate. Rank higher in Google with a faster loading site.

Last verified: July 17, 2026 · Fresh

App details

Developer: Speed Boostr
Category: Store design
Pricing: Paid
Launched: March 2021
Rating: 2.4 (5) on Shopify

Key features

Inline your Critical CSS to eliminate render-blocking resources
This will speed up your store

1 plan · 10-day free trial

One-time charge

$10 one-time

Plans and prices as listed on the Shopify App Store.

Ratings & reviews

based on 15 Shopify App Store reviews

Use the arrows to read individual reviews

Great app. Simple to use and seems to be effective.

— Home Team Heroes

KRAZY! That's all I can say. What a totally brilliant app. For a measly $10 our Pagespeed score went up >25%. How can you beat that? Try the app – you'll see. And then once you experience what we've experienced – continue to periodically rerun the app from time to time, to sort out changes that you make to your store. Possibly the best $10 investment ever!

— ExcellentSupply.com

The app does a more measurable progress on mobile download speed increasing First Contentful Paint which was around 3.4 s on a collection page, now app installed it is about 1.3 s. Overall our Google Pagespeed score increased around 5 - 8 points for the same collection page.

— Cymbal House

A quick and easy way that made our site snappier with first visits and slower connections where the browser needs to initial cache. This did not make lighthouse faster for us, perhaps a misconception of what critical CSS does, but it does make real world load time faster and lowered our blocking time.

— CARZILLA

Eine App mit gutem Kundenservice, also null Risiko. Ich kann daher diese App mit gutem Gefühl weiter empfehlen.

— majorcom-fachhandel

This has to to the best app in the shopify apps store to help you be successful. I will admit I am using FLEX so I had really good page load but with Critical CSS 1.32 sec loading time. Never been able to achieve that with many attempts with other themes. I think I have the right combo now. Thank you!

— Coastal Gifts Inc

"Instant pagespeed increase for $10... yeah right?!" That's exactly what I said when I saw this app but thought I'd give it a go anyway, SO GLAD I DID! Having spent a few days trying to boost the speed of our store and only getting marginal gains my research lead me to this app. The install was super easy and instantly flagged up some unseen errors in my CSS (blame my template creators for that!),...

— Skatewarehouse.co.uk

One day since install opinion: This helps us stream line our CSS and in conjunction with some other fixes we were able to get our page speed score up from a 28 to a 90(at its peak on mobile)! Great customer service, alex responding quickly and was ready to help however we needed. This is a one man team and he's doing great job!

— NatureCity

I've run all possible tests while trying to change everything manually to get the site to run smoother and the changes were minor. After installing the app the performance scores went up by a LOT. Especially mobile scores. Thank you for the great app.

— Crescent Chalice

Installation nicht möglich. Man installiert, zahlt und die App verlangt erneut die Gebühr - VORSICHT. 2 Mal die Gebühr bezahlt und geht immer noch nicht. Habe dem Support beide Rechnungen geschickt, die behaupten, ich hätte nicht bezahlt. shopify bestätigt die beiden Zahlungen, doch den Betreiber interessiert es nicht wirklich anstatt die App frei zu schalten, wurde ein Shopzugriff verlangt nur...

— BLOODY-STREETS.DE

Não funciona … Fiquei semanas esperando correção pelo suporte e sem retorno agradável .. Não indicado

— Bs Multimarcas

I wouldn't say I like leaving negative reviews, but what can you do if support doesn't reply and the app that I had to pay for to try it out does not work and simply breaks the template? The support started ok, with about a 3-day wait, but they did fix one issue after reporting that the app was still not working and had removed the cart buttons. No replies from my support ticket at all. I chased...

— The Fashion Gift Shop