Comparison
Klaviyo vs Postscript
Klaviyo SMS vs Postscript on the Shopify-first SMS channel — pricing verified 2026-05-30, Customer Agent vs Shopper, and verdict by store revenue and email maturity.
Klaviyo
"AI Email Marketing & SMS | B2C CRM" — the autonomous B2C CRM that unifies email, SMS, RCS, WhatsApp and push.
Postscript
"SMS Marketing and Sales for Shopify Brands" — Shopify-only SMS platform.
Affiliate link. Pricing and terms are set by the vendor. details
On this page
At a glance
Klaviyo and Postscript both sell SMS to Shopify operators, but they're solving different problems. Klaviyo bundles SMS into a multi-channel B2C CRM — email, SMS, RCS, WhatsApp, push, and a unified customer profile billed on active-profile count. Postscript is 100% Shopify-only SMS, billed on monthly platform fee plus per-message usage, with a stated 130M+ Onsite Opt-in Network and the Shopper AI shopping assistant. The decisive question is not "which is better at SMS" — both ship competent SMS engines. It's "do you already have email running well at $50K+/mo MRR, and do you want SMS managed alongside it (Klaviyo) or as a specialist channel (Postscript)." A close second: how do their AI agents — Klaviyo Customer Agent and Postscript Shopper — compare for autonomous shopper conversations.
Quick stats
Starting price
Klaviyo
$20/mo
Postscript
$49/mo
Rating
Klaviyo
8.4/10
Postscript
8.5/10
Integrations
Klaviyo
8
Postscript
5
Pricing model (verified 2026-05-30)
Klaviyo
Active profiles tiered, Email from $20/mo; SMS bundled in Email + SMS plans
Postscript
Usage-based: $25/mo Starter + $0.015/SMS, $0.045/MMS (US baseline)
Channel scope
Klaviyo
Email + SMS + WhatsApp + RCS + push + voice (multi-channel CRM)
Postscript
SMS / MMS / RCS only — no email channel
AI agent for shopper conversations
Klaviyo
Customer Agent — separate consumption-based helpdesk product
Postscript
Shopper — included in Postscript AI Plan; conversational commerce on SMS
Free tier
Klaviyo
Free $0: 250 active profiles, 500 emails/mo, 150 SMS credits
Postscript
None — Starter requires $25/mo platform fee + minimum spend
Pricing
Klaviyo
$20/mo
- up to
- —
- Model
- tiered
Tiers: Free $0 (250 active profiles, 500 emails/mo, 150 SMS credits); Email from $20/mo for 251-500 active profiles; scales with active-profile count up to ~$2,300/mo at 250K profiles Pricing gotchas: Billed on active profiles, not emails sent; Klaviyo One mandatory above ~$10K/mo (+20%). Free plan: Yes—250 profiles/500 emails/150 SMS credits Verified 2026-05-30
Postscript
$49/mo
- up to
- —
- Model
- usage-based
Tiers: Starter $0/mo + $49 minimum spend; Growth $100/mo; Professional $500/mo (most popular); Enterprise custom SMS rates (descending by tier): Starter $0.015 → $0.009/msg, Growth $0.01 → $0.008/msg, Professional $0.007/msg; MMS Starter $0.045, Growth $0.03, Professional $0.024 + carrier fees. Pricing gotchas: Shifted from pure usage-based to monthly platform fee + per-message in 2025-2026; Starter minimum raised from $25 to $49; free trial credit reduced from $1,000 to $100. Carrier fees passed through (US SMS avg $0.0040, MMS $0.0083). DSC $750/mo carrier passthrough. Free plan: No—30-day trial with $100 usage credit Verified 2026-06-03 against postscript.io/pricing
Klaviyo starts at $20/mo vs Postscript's $49/mo. Pricing models differ: Klaviyo is tiered, Postscript is usage-based.
Klaviyo: Free $0 (250 active profiles, 500 emails/mo, 150 SMS credits). Email tier from $20/mo at 251-500 active profiles, scales by active-profile count up to ~$2,300/mo at 250K profiles. Above ~$10K/mo total spend, Klaviyo One enterprise becomes mandatory and adds 20% to the bill (per Klaviyo Help Center). Billing changed February 18, 2025 from emails sent to ACTIVE PROFILES — surface this when modeling cost at higher tiers. Postscript: Starter from $25/mo (includes minimum spend); Growth from $100/mo; Professional ~$500/mo; Enterprise custom. SMS $0.015 / MMS $0.045 US baseline (decreases on higher tiers); international SMS $0.25/msg on Starter/Growth/Pro; carrier fees pass-through; dedicated short code +$750/mo. The new monthly platform fee + per-message usage model hit longtime users hard per recent Shopify App Store reviews ("I LOVED Postscript. And then this year they instituted a new monthly charge in ADDITION to charges per message sent" — Shopify App Store 2026).
Features
Klaviyo
- Predictive Analytics (CLV / Churn Risk / Next Order Date) — Predicts customer lifetime value, churn probability, and expected next purchase date per profile
- Klaviyo AI (generative content) — Generates subject lines, email copy, SMS copy, and form copy in brand voice
- Klaviyo Data Platform (Advanced KDP) — Customer data platform layer with advanced data ingestion, identity resolution and segmentation
- Customer Hub — Branded self-service customer portal showing orders, loyalty, recommendations
- Marketing Analytics — Cross-channel attribution and advanced marketing reporting
- Helpdesk / Customer Agent — Native helpdesk product with AI Customer Agent for ticket resolution
Postscript
- Infinity Testing — Test hundreds of on-brand SMS variants automatically for campaigns and automations
- Shopper (1:1 AI shopping assistant) — AI-powered 1:1 SMS shopping assistant that answers questions and drives purchases
- Conversation Intelligence — Extracts insights from SMS conversations to inform marketing and product decisions
- CashBack (smart coupon alternative) — Pay incentives only when customers redeem them, protecting contribution margin
- Postscript Plus (managed service) — Done-for-you managed SMS marketing with expert strategists
- SMS Sales (human-agent SMS sales team) — Dedicated SMS sales agents that proactively engage subscribers via text
Shopify integration
Klaviyo
Deep native Shopify integration; Shopify App Store; Built-for-Shopify; near real-time sync of customers, products, orders and events; native Customer Hub for Shopify storefronts; Klaviyo SMS supported; embedded forms and popups
Postscript
Deep native Shopify integration; Shopify App Store; built specifically for Shopify and Shopify Plus; subscriber sync via Shopify customer data
Integrations
Only Klaviyo
- Google Ads
- Segment
- Snapchat
Both
- Meta
- TikTok
Only Postscript
- Shopify
Customer support
Support rating (aggregated from independent review platforms like G2, Capterra, Shopify App Store): Klaviyo 8.4/10, Postscript 9/10. This is an editorial composite of channel availability, response speed, and resolution quality — see the individual reviews below for specifics.
Pros & cons
Klaviyo
Pros
- Deep Shopify integration & flow builder
- Behavioral segmentation depth (9.0 G2 score)
- Predictive AI / CLV scoring
Cons
- Steep price scaling as contacts grow
- Support quality drops on lower tiers
- Reporting requires data exports for advanced analysis
Postscript
Pros
- Pure-play SMS focus + deep Shopify integration
- Strong segmentation (45+ Shopify-specific filters)
- Compliance engine reduces TCPA risk
Cons
- New monthly platform fee + per-message charges frustrate longtime users
- Slow human support replaced by AI bot
- Shopify-only — no WooCommerce or BigCommerce
When each one wins
Winner: Klaviyo
Email-first store under $50K/mo MRR, no SMS yet
Klaviyo's free tier (250 active profiles, 500 emails/mo, 150 SMS credits) is the entry point most stores already use for email; adding 150 SMS credits inside it is the cheapest possible way to test SMS without a second platform contract. Klaviyo SMS is competent enough for transactional and welcome flows. Migrate to specialist tooling later if SMS becomes a real revenue channel — the data from the Klaviyo SMS pilot helps justify the move.
Winner: Postscript
$50K+/mo MRR with serious SMS revenue ambitions
Postscript's 45+ Shopify-specific segmentation filters, compliance engine (reduces TCPA risk), and 4x ROI guarantee are things Klaviyo doesn't match — Klaviyo treats SMS as one channel of many; Postscript treats it as the only channel. If SMS will drive >15% of marketing revenue, the specialist gains compound. Caveat: recent Shopify App Store reviews flag the new monthly platform fee + per-message billing as the model that broke longtime user trust — verify the 4x ROI math on your own list before commitment.
Winner: Postscript
Need AI agent for shopper conversations (Customer Agent vs Shopper)
Postscript Shopper is a 1:1 AI shopping assistant on SMS — conversational commerce that answers product questions and drives purchases. It is part of the Postscript AI Plan and sits on the channel where shoppers actually respond in real time. Klaviyo Customer Agent is a separate helpdesk product priced by consumption — it resolves support tickets, not pre-purchase shopping. Different problems despite similar "AI agent" branding. For pre-purchase conversational AI on SMS, Postscript Shopper is the closer fit. For post-purchase support deflection across channels, Klaviyo Customer Agent (or a dedicated helpdesk like Gorgias) is the closer fit.
Our verdict
Klaviyo and Postscript split cleanly by store maturity and SMS ambition. Below $50K/mo MRR — Klaviyo's bundled SMS inside the free or Email tier is the cheapest, fastest way to test SMS without onboarding a second platform. Above $50K/mo MRR with SMS as a real revenue channel — Postscript's Shopify-only specialist depth (45+ Shopify-specific segmentation filters, compliance engine, 4x ROI guarantee) pays back faster than Klaviyo SMS. The Customer Agent vs Shopper question is misleading: they solve different jobs. Postscript Shopper is pre-purchase conversational AI on SMS; Klaviyo Customer Agent is post-purchase ticket resolution priced separately as a helpdesk product. Don't pick the tool to get the AI agent — pick the tool to get the channel strategy, and the agent fits the job naturally. For the full Postscript pricing breakdown ($49 Starter minimum + platform-fee shift), see /pricing/postscript. For the full Klaviyo pricing breakdown (active-profiles billing trap + Customer Agent $200/mo), see /pricing/klaviyo.
Similar tools worth comparing
Omnisend
"Email and SMS Marketing for Ecommerce Businesses" — ecommerce-focused email & SMS automation built on feedback of 150,000+ brands.
8.8/10Free · from $0/moRead reviewGorgias
"The Conversational AI platform for Ecommerce" — the #1 Helpdesk + AI Agent built to drive sales.
8.6/10from $10/moRead review
Klaviyo
"AI Email Marketing & SMS | B2C CRM" — the autonomous B2C CRM that unifies email, SMS, RCS, WhatsApp and push.
Postscript
"SMS Marketing and Sales for Shopify Brands" — Shopify-only SMS platform.
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