FlashDrop

FlashDrop is a Shopify app for group-buy launches: a merchant creates a drop campaign on a product with a ladder of milestones, each a target number of units and the discount it unlocks. Shoppers "join" through a storefront widget showing how many have joined and the next milestone; joining places a real order but only authorizes payment rather than charging it up front. When the campaign ends, the backend works out the highest milestone the group reached, retroactively applies that discount to every joiner's order using Shopify's order-editing API, and only then captures the deferred payment for the discounted total.

The work is split across two codebases: a Remix admin plus Shopify extensions handle the merchant UI and live checkout mechanics, while an Elixir/Phoenix backend owns the settlement engine, campaign data, order-webhook intake, and the milestone-resolution job. The mechanic is purely participation-based, price moves with how many people join rather than with live inventory levels, and a separate live feature can add a free sample to a cart at checkout.

FlashDrop is live on the Shopify App Store, currently unlisted and reachable by direct link rather than public search. Its distinctive core is the deferred-settlement group-buy flow.