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Fastest Shopify email and SMS marketing apps, ranked on live stores

We ranked 6 email and SMS marketing apps by the processing time each added to the homepages of real Shopify ecommerce stores. The lightest are at the top.

What counts here: Sends marketing email or text messages, including the sign-up forms that collect subscribers.

The most recent check in the index ran on September 26, 2026.

All apps in the index · How we measure these numbers

ShopWeight isn't affiliated with Shopify or with any app maker listed here.

Popular apps and the processing time they add

Among this category's apps that are light or moderate on the typical store, Attentive is found on the most stores.

LightModerateHeavyVery heavy Fewer stores, lighterMore stores, lighterFewer stores, heavierMore stores, heavier Klaviyo: heavy on the typical store, found on 496 storesKlaviyoAttentive: light on the typical store, found on 139 storesAttentivePostscript: light on the typical store, found on 59 storesPostscriptAfterShip Email Marketing: light on the typical store, found on 25 storesAfterShip Email MarketingMailchimp: light on the typical store, found on 24 storesWunderkind: light on the typical store, found on 24 stores Typical processing time Stores measured

The vertical dashed line is at 42 stores: about half of this category's apps were found on more stores and half on fewer. The horizontal dashed line is where moderate ends and heavy begins.

RankAppTypical processing timeStores measured
1 Attentive Light (under 100 ms) 139
2 AfterShip Email Marketing Light (under 100 ms) 25
3 Mailchimp Light (under 100 ms) 24
4 Postscript Light (under 100 ms) 59
5 Wunderkind Light (under 100 ms) 24
6 Klaviyo Heavy (300 ms to 1 second) 496

Apps in the same band are close. Their order within a band can change as more stores are checked. The bar under each band shows how the app varied from store to store. Apps found on fewer than 20 stores aren't listed yet. The list grows as more stores are checked.

Compare two email and SMS marketing apps

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