Comparison
InstantPWA vs Postscript
Shopify SMS, or a free installed-app channel?
Postscript is built specifically for Shopify SMS marketing and list growth. InstantPWA is stack-agnostic and adds a different acquisition surface — an installable PWA with push — that carries no per-message sending cost once a visitor installs.
Works on any e-commerce stack
InstantPWA
Yes
Postscript
No
SMS marketing & automations
InstantPWA
No
Postscript
Yes
Home-screen install popup
InstantPWA
Yes
Postscript
No
Per-message sending cost
InstantPWA
None
Postscript
Per SMS
Free plan
InstantPWA
Generous
Postscript
Trial only
When to pick which
Use Postscript if you are Shopify-only and SMS list growth and automation are your priority. Use InstantPWA when you want a complementary, cost-free channel via installs and push, or run on a non-Shopify stack.