Most rules apps make you publish first and discover mistakes later. Drydock simulates delivery, payment, and validation rules against carts you control, re-runs your saved tests on every publish, and restores any earlier version in one click.
No card. Nothing changes at your checkout until you publish — and you approve the install on Shopify's own screen.
One wrong rule can hide your best shipping rate
Express shows for a PO box your carrier won't deliver to
Cash on Delivery stays enabled on high-value orders
Wholesale-only rates leak to retail customers
A postcode rule quietly blocks legitimate buyers
Merchants usually find out from support tickets and abandoned carts. Drydock finds out in the simulator, before anything goes live.
Build → Simulate → Test → Publish → Restore
1 · Build in plain English
Conditions on address, cart, and customer; actions on shipping options, payment methods, or checkout itself. No code, no theme edits.
2 · Simulate any checkout
Run the draft against a synthetic checkout — any address, any cart, real products from your catalog. See exactly what the customer would see, and why: every condition, its actual value, pass or fail.
3 · Tests re-run on every publish
Save good scenarios as test cases. Every publish re-runs the whole suite first — a rule that changes an outcome you didn't expect gets flagged on the publish screen, not by customers.
4 · Publish as a version. Restore in one click.
Every publish is an immutable version with a readable diff. Restore any previous published version in one click — every version stays in your history.
Proof at a real checkout
Rules run natively inside Shopify checkout as WebAssembly — no storefront scripts, no rate delays. Same address, before and after the PO-box rule:
Straight answers
Same rule logic, twice-compiledThe simulator runs the same compiled rule engine we deploy to your checkout — one codebase, two builds.
What isn't simulatedLive carrier-calculated rates, other checkout apps, and data Shopify doesn't provide to Functions. Your saved tests cover the scenarios that matter.
No customer data storedRules evaluate inside Shopify's checkout runtime. Drydock's servers never see or store customer data. Privacy
Nothing live until you publishInstall, build, and simulate freely — your checkout doesn't change until you press Publish.
