What the data says: Across 238 operator reviews touching these SMS platforms — 209 Klaviyo, 22 Attentive, 7 Postscript — 71% rated their app "Very Satisfied" and 94% still actively use it. Here's how they compare for SMS specifically.

Short version: Attentive if SMS is a serious standalone channel and you want the category leader, Postscript if you want strong SMS with friendlier pricing, and Klaviyo SMS if you're already on Klaviyo for email and want texts in the same platform. Klaviyo wins on convenience, Attentive wins on SMS depth, and price runs through every decision.

SMS platforms at a glance

Should you just use Klaviyo for SMS?

If you already run Klaviyo for email, it's the convenient default — one platform, shared flows and segments. But operators are direct that SMS is the weaker half of the product.

"The SMS part of the app is still behind other services such as Attentive."

The SMS integration is "pretty average and unnecessarily expensive."

One flagged a real functional gap: no true two-way conversation when a customer replies. Run SMS through Klaviyo if texting is secondary and single-platform simplicity matters most. Full detail on our Klaviyo review page.

Is Attentive worth the premium for SMS?

If SMS is a serious channel, largely yes — operators are unusually direct that it's the leader. Of 22 reviews, 18 still use it.

"The leader in SMS but also the leader in customer service."

Conversions "are better with SMS than with Klaviyo."

The white-glove Customer Success service, 2-tap signup units, and AI send-time tools earn repeated praise. The complaints cluster on cost and contracts:

"Overpriced" with "a lot of line items" — and one operator "locked to a long-term contract" planning to switch.

Verdict: worth the premium when SMS revenue justifies it; painful if you're paying enterprise rates for light usage. Full detail on our Attentive review page.

When is Postscript the right call?

When you want strong SMS with friendlier pricing and less enterprise overhead. Smaller sample (7 reviews), but consistent — and operators compare it head-to-head with the others.

"I can get a message out in minutes, even on the phone."

It "converts better than Klaviyo SMS right now," with "aggressive pricing."

The honest caveats: a couple saw opens and conversions soften over the past year, and one called the UI "inferior to Attentive." Postscript fits a store that wants a capable, cost-conscious SMS tool without Attentive's service layer.

So which SMS app should you choose?

One rule for all three: check the attribution yourself. Every platform here was flagged by operators for generous, self-reported ROAS — they count a sale if a text was anywhere nearby. Trust your blended numbers and Shopify data over the app's dashboard.

SMS pairs with email — our Klaviyo vs Omnisend vs Mailchimp email comparison covers the other half.

Run SMS on one of these? Your channel numbers are worth money. This comparison came from operators sharing what actually converted — and where attribution was inflated. Shopify app teams pay $50 to $500 per call to hear it firsthand, and you get early access to the tools you help shape. Get paid for the opinion you already have. Join as a brand →

Operator statistics and quotes are from verified app reviews collected inside the app store research network, July 2026. Sample sizes vary and are noted where small. App pricing and features change; confirm current details on the Shopify App Store before purchasing.