What is Postscript?
Postscript is an SMS marketing and retention platform built for Shopify brands that want to sell more to existing customers through text messages, RCS and email. It installs as a Shopify app, pulls in store and customer data, and uses it to send campaigns and automated flows. The company has rebuilt the product around AI, with agents that act on context about each brand and each subscriber.
Key parts of Postscript include onsite opt-in tools for list growth, Shopper for AI-driven one-to-one shopping conversations, and Infinity Testing for fast message experiments. A Brand Center keeps AI messages on-brand, and compliance guardrails are built in. Email is rolling out in phases. Brands that want outside help can add Postscript Plus, a team of in-house SMS strategists.
Postscript at a glance
How does Postscript work?
- Install the Shopify app
Add Postscript from the Shopify App Store and start a 30-day free trial.
- Grow your list
Use onsite opt-in tools and keywords to collect SMS subscribers with consent.
- Set brand and customer context
Define brand guidelines so AI-generated messages match your voice and use store data.
- Launch campaigns and flows
Send campaigns and automated flows, or let Shopper hold one-to-one conversations.
- Test and optimize
Run Infinity Testing to compare message versions and improve revenue per subscriber.
Postscript key features
Onsite opt-in
Website sign-up experiences for capturing SMS subscribers.
Shopper
AI-powered one-to-one journeys that recommend products and answer questions by text.
Infinity Testing
Runs many message variations at once to find what performs best.
Brand Center
A control panel that keeps AI-written messages consistent with your brand.
Agentic Context Platform
Stores brand and customer context for AI agents, included on every plan.
RCS and email
Branded rich messages and email alongside SMS, with email in phased rollout.
Postscript Plus
An optional managed service where strategists run your SMS program.
Why use Postscript?
- Turn Shopify customer data into targeted text campaigns and flows.
- Start with no monthly fee on the Starter plan and pay per message sent.
- Test message ideas faster with automated experimentation.
- Use AI for one-to-one shopping conversations at scale.
- Avoid prepaid credits and overage charges, since you pay after you send.
Who is Postscript best for?
A good fit for
- Shopify and Shopify Plus ecommerce brands
- Direct-to-consumer brands focused on repeat purchases
- Growing stores that want transparent per-message pricing
- Brands that want optional managed SMS strategy
Less suited to
- Stores not running on Shopify
- Service businesses that mainly need appointment reminders or two-way support texting
Postscript pricing
| Pricing model | Usage-based |
|---|---|
| Free plan | No |
| Free trial | 30 days |
| Starting price | Starter: $0/month plus per-message fees ($49 monthly minimum spend) |
Growth costs $100 per month and Professional $500 per month, each with lower per-message rates and more features. Carrier fees are extra, and a separate AI plan and custom Enterprise pricing are available.
Prices checked October 2026. Vendors change plans often, so confirm on the official Postscript pricing page before you buy.
Postscript pros and cons
Pros
- Deep Shopify integration
- Published per-message pricing
- AI tools for testing and one-to-one selling
- No prepaid credits or overages
Cons
- Limited to Shopify stores
- Carrier fees add to the listed per-message rates
- Email is still in phased rollout
Postscript integrations and platforms
Works with
Available on
Postscript alternatives
See the full shortlist in Best SMS Marketing Platforms.
Postscript FAQ
How much does Postscript cost?
Postscript's Starter plan has no monthly fee, but it carries a $49 monthly minimum spend and charges per SMS and MMS. The Growth plan costs $100 per month and Professional costs $500 per month, each with lower message rates. Carrier fees are added on top, and every plan starts with a 30-day free trial.
What is Postscript used for?
Postscript is used by Shopify brands to grow SMS subscriber lists and send marketing texts that drive repeat purchases. Stores run promotional campaigns, automated flows such as abandoned cart reminders, and AI-led one-to-one conversations through Shopper. It also supports RCS, and email is being added in phases.
Does Postscript work without Shopify?
Postscript is designed for Shopify brands and installs as a Shopify app. Its store data connection, flows and customer context all depend on Shopify. If your store runs on another ecommerce platform, a multi-platform SMS tool is likely a better fit than Postscript.
Postscript vs Attentive: what's the difference?
Postscript focuses on Shopify stores and publishes its plan fees and per-message rates. Attentive supports more commerce platforms and channels, including email, RCS and push, but uses custom quotes. Smaller and mid-size Shopify brands often prefer Postscript's clear pricing, while larger multichannel retailers may lean toward Attentive.
Does Postscript integrate with Klaviyo?
Yes. Postscript's Shopify App Store listing names Klaviyo among the apps it works with, along with Gorgias, Privy and Zapier. Many brands use Klaviyo for email and Postscript for SMS, sharing subscriber data between them. An API is also available on higher plans for custom connections.
Sources
This overview is based on Postscript's official website and documentation, checked October 2026.