Vault: A Shopify Promotions Engine With a Pre-Launch Risk Audit

Discount apps fail quietly. The bad ones are easy to spot — the campaign never goes live, or it goes live with an obvious bug the merchant catches in the first five minutes. The dangerous ones run clean for four days and silently cost the store its entire Black Friday margin on a gift-card stacking chain nobody caught.

Most discount apps on the Shopify App Store are good at the first four days. Very few are honest about the fifth.

Vault is the promotions and sales system we wished every one of our Shopify clients had when we were still doing consulting. It handles the long tail of discount rules behind a wizard with live previews, and it runs a pre-launch risk audit against the failure modes that actually matter. A promotion without an end date is a liability disguised as a campaign.

The twenty-two discount types

Vault supports every discount shape we have seen ship in production across two decades of Shopify work. They are not all equally used; they are all there because at some point a merchant needed one and had to bolt three apps together to get it.

1. Percentage off — the baseline. Vault scopes it by product, collection, customer segment, or cart composition.
2. Fixed amount off — scoped the same as percentage.
3. BOGO (buy-one-get-one) — with explicit rules for whether the gift repeats, whether it stacks with other discounts, and what happens at the cart level when the gift is removed.
4. Tiered volume discount — 5% at 3 units, 10% at 6, 15% at 10. Caps optional.
5. Product bundles — fixed price, percentage off the bundle total, or margin-floor-protected.
6. Mix-and-match bundles — bundle composition across collections with minimum-quantity rules per category.
7. Customer-tag gating — discount available only to customers carrying a specified tag (VIP, wholesale, staff, NDA).
8. Customer-segment gating — the same, but computed from Shopify’s segments rather than static tags.
9. Location-scoped POS — discount valid only at specified POS locations, or only online.
10. Device-scoped POS — finer-grained than location; a specific POS device can honour a staff-only discount without exposing it to the storefront.
11. Time-window discounts — start and end datetimes with timezone awareness.
12. Recurring time-window (Happy Hour) — e.g. weekdays 4–6pm only, or every Friday, with DST handling.
13. Velocity escalation — the discount depth increases when sell-through crosses a threshold within a window (hour-bucketed or rolling).
14. Velocity clamping — the opposite: depth decreases or promo pauses when inventory burns too fast.
15. Cart-value threshold — percentage or fixed off above a cart total.
16. Cart-composition requirements — must include SKU A and (SKU B or SKU C).
17. Quantity-gated BOGO — buy three, get one free; buy five, get two.
18. Free shipping — conditional or unconditional, with zone-aware fallbacks.
19. Free-gift unlock — a specific SKU added to the cart at zero cost when conditions are met.
20. Referral-code chains — tracked codes with downstream attribution.
21. One-time-use vs reusable — all of the above in single-use or repeatable variants.

Twenty-two types is an inventory, not a boast. A well-run promotions programme uses a small handful of them well.

The risk audit

The audit is the product. Every promotion Vault is about to ship gets scored against a catalogue of known failure modes. Some are mundane; some have cost real merchants real money.

Missing end dates. The most common, and the most expensive. A flash sale was supposed to end at midnight Sunday. It did not. By Tuesday morning the merchant has either shipped three days of over-discounted orders, or customer-support has a queue of people asking why the code stopped working at 11:59.

Stackable gift chains. BOGO + percentage off + free-gift-unlock, combined, means a buyer can end up paying less than the cost of the free gift for a cart. The audit traces every combinable path at a range of cart sizes and flags the negative-margin corners.

Negative-margin pairs. Two discounts, neither problematic alone, together push the blended margin below the floor. Vault knows your margin floor because you set it, and refuses to ship the pair without an explicit override.

POS/online price drift. The most insidious. A discount ships online but is not propagated to POS, so customers pay one price in the store and another on the site. This is a support nightmare after it hits a regional chain’s Instagram.

Cart-recovery drift. A cart-recovery email references a code that has since expired. The audit tracks which codes are referenced in active flows and warns when one is about to expire.

Tag-scope drift. A customer tag moves out of eligibility during a subscription billing cycle. Vault’s audit flags promotions where the tag-eligibility window does not align with the billing window.

A campaign that passes the audit is not guaranteed to succeed. A campaign that fails the audit is guaranteed to leak.

The wizard and live previews

Every promotion is composed in a single wizard, with a live preview of what the cart will look like at representative cart sizes. The preview is what actually prevents the stacking chains — you can see, before the campaign ships, that a hypothetical cart of (1 bundle + 1 BOGO unit + a free-gift unlock) pays $4.18 when the math says it should pay $38.

The preview is not a simulation. It runs the same engine that will run in production, against the same rules you just composed. If the preview shows the right number, the cart will show the right number.

One workflow sketch: Black Friday prep

A merchant running a brand storefront at eight-figure GMV typically ships thirty to fifty promotions in the BFCM window. Vault’s workflow for that looks like:

1. The ops lead composes each promotion in the wizard. Each one gets a draft name, a rules-block, a time window, and margin guardrails.
2. The audit runs automatically on save. Issues surface as warnings (soft) or blocks (hard). Blocks require an explicit override with a reason, logged.
3. A dry-run across representative carts runs before any promotion goes live. The preview cart matrix flags any gift-stacking chain the auditor did not catch structurally.
4. Campaigns ship with staggered go-live times so the POS and online stores synchronise before peak traffic.
5. Post-window, the audit runs backwards — any promotion where the actual discount depth diverged from the intended depth surfaces for a post-mortem.

Thirty-five promotions, one wizard, one audit pass. This is what we mean by a promotions system operators can bet on.

What Vault is not

Vault is not a loyalty platform. It does not manage customer points, tiers, or referral rewards beyond the tracked-code level. It is not an email marketing platform — when you need discount codes for email broadcast, the email tool (Klaviyo, Omnisend, Mailchimp) generates the codes and Vault enforces the logic at the Shopify layer. It is not a subscription-billing tool.

Vault does one thing. That thing is often the thing ops teams spend the most time in during a peak season. If you need a promotions system that outlives the vendor-of-the-year cycle, Vault is on the Shopify App Store.

Related reading:

• How to Stack Shopify Discounts Without Breaking Margin — five real stacking patterns and their guardrails.
• Shopify Discount Apps Compared: Vault vs Discounty vs Bold vs BOGOS — a side-by-side feature matrix.