Tweakify

Tweakify adds unlimited custom product options to Shopify stores without touching Shopify's variant system, which normally caps a product at three options and a hundred variants. A merchant builds "option sets" in an embedded admin builder from a catalogue of 80 field types, text, uploads, dates, dimensions, choices and more (72 are fully built), and assigns them to products. On the storefront, fields can show, hide or become required based on other answers, and a running price updates live as a shopper fills the form in.

When a shopper adds to cart, their choices attach to the line as properties rather than a fake variant, and a compiled Shopify Function, a Cart Transform running as WebAssembly at checkout, independently re-derives the add-on price from the merchant's saved configuration before checkout, so the browser total is display-only and cannot be tampered with. The storefront engine and the checkout Function run in different runtimes and cannot share code, so the pricing logic is hand-ported between them and covered by a parity test suite that guarantees byte-identical results. The builder and storefront are localized across eight languages.

Tweakify's development is complete and localized, awaiting Shopify App Store review. Server-side charging is unit- and parity-tested and validated on a Shopify development store.