Inventory across channels. Consignors across locations. One AI-native system.
StackKnack prices items at intake, flags aging stock before consignors call, syncs every channel in real time, and calculates payouts automatically.
When you sell on three channels and run consignment, spreadsheets stop working.
A Shopify store, an eBay storefront, a Clover POS at the counter, and dozens of consignors with different splits — generic inventory tools weren’t built for this combination. StackKnack was.
Item sells on eBay. Shopify listing is still live. A second buyer checks out. Manual delisting doesn’t scale — one mistake destroys customer trust.
50+ consignors, each on different splits, tracked in a spreadsheet. One wrong payout and a consignor loses trust — and tells others.
A customer asks about an item at your other location. Staff have to text to find out. No single view means slow answers and lost sales.
From intake to payout — one workflow
Four steps to give your operation complete visibility from the moment an item arrives to the moment your consignor gets paid.
Item arrives. Assign a unique SKU, capture condition, set the consignor split, and specify the location. Every item is trackable from the moment it comes in.
Push inventory to Shopify, eBay, and Clover POS. When something sells anywhere, it’s marked sold everywhere — automatically.
Ring up in-store sales through kiosk mode. Log what customers ask about — and follow up with a targeted email when the right item arrives.
Item sells → payout calculated from split agreement → consignor record updated. No manual math, no reconciliation, no disputes.
Not a chatbot. Proactive intelligence built into every step.
StackKnack doesn’t wait for you to ask. It surfaces pricing recommendations at intake, flags aging inventory before consignors call, reads demand signals from your floor, and writes optimized listings for every channel automatically.
Item comes in — StackKnack instantly pulls comps and suggests a price. No manual research, no guesswork, no leaving money on the table.
Before a consignor calls about their item, StackKnack already flagged it — with the exact markdown needed to move it and the payout impact before you decide.
Every customer interest logged in-store becomes a buying signal. StackKnack tracks what’s being asked for, matches it against comp trends, and tells you what’s worth sourcing.
StackKnack writes the listing title and description for you — optimized for eBay search ranking, Shopify SEO, and channel-specific buyer language. One intake, every channel ready.
Two ways your systems can plug in
StackKnack exposes its full resale platform via MCP server and GraphQL API. Connect AI agents, integrate with your Shopify app or POS system, or build custom internal tooling — all against the same production data your operations team uses.
AI agent integration
Connect any AI agent and let it run resale workflows autonomously in natural language.
- Price items at intake from real-time comps
- Generate SEO-optimized eBay and Shopify listings
- Sync inventory across all channels instantly
- Calculate and generate consignor payout reports
Platform integration
Connect StackKnack to your existing Shopify apps, POS setup, or internal tooling via a flexible GraphQL API.
- Create and update inventory items programmatically
- Query consignor records and payout status
- Retrieve sold comps for any brand, model, and condition
- Trigger channel sync events from external systems
Everything a resale operation actually needs
Built specifically for multi-channel resale and consignment — not adapted from generic inventory software.
- Unique SKUs per item — resale-native
- Real-time stock across all locations
- Full inventory change history & audit trail
- Inventory audits & reconciliation tools
- Smart collections + dynamic price rules
- Track consignor-owned vs store-owned separately
- Per-consignor commission rules & splits
- Automatic payout calculation on sale
- Transparent payout history per consignor
- Vendor purchase tracking alongside consignment
- Shopify, eBay & Clover POS sync
- In-store kiosk + Stripe payments
- Customer interest & browsing tracking
- Targeted follow-up emails from interest data
- Role-based staff access & permissions
What changes when inventory is actually under control
Real-time sync across Shopify, eBay, and in-store means when an item sells anywhere, it’s gone everywhere. No more manual delisting, no more angry customers.
Payout calculations are automatic and based on agreed splits. Every consignor has a clear record. No manual math means no mistakes — and no disputes.
Real-time visibility across all your stores and warehouses. Staff answer stock questions instantly. You see the full picture without calling around.
Track what customers browse and ask about in-store — even if they leave empty-handed. Use that data to follow up when the right item comes in.
Purpose-built for specialty resale and consignment shops
High-volume SKUs · Shopify + eBay multi-channel · consignment + outright buy
2–10 locations · centralized inventory view · unified consignor management
Consignor-heavy model · payout accuracy · multi-channel listings
Ready to add channels · replacing spreadsheets · building operational structure
We don’t just hand you software — we make sure it actually runs your operation
Every customer gets hands-on onboarding. We configure your consignor commission structures, connect your channels, verify inventory accuracy, and stay with you until things run correctly.
For multi-location operations, we go location by location — no store goes live until it’s working right.
See StackKnack in action for your resale operation
Book a 30-minute walkthrough built around your operation — your channels, your consignor model, your locations. We’ll show you exactly what it looks like when it’s running correctly.
- See live inventory sync across Shopify, eBay, and in-store
- Walk through consignor payout calculation with real data
- Get honest feedback on fit — including if we’re not the right tool
Common questions, answered directly.
Spreadsheets break at scale — they can’t sync across Shopify and eBay in real time, can’t track which items belong to which consignor, and have no audit trail when something goes missing. StackKnack replaces that patchwork with a single system that tracks every item from intake to sale, across every channel you sell on — and surfaces pricing recommendations, aging alerts, and demand signals automatically as you go.
StackKnack syncs inventory with Shopify, eBay, and Clover POS. When an item sells on any channel — or in-store — it’s updated across all of them. No manual delisting, no double-sells from mismatched counts.
Each consignor has their own commission structure configured in StackKnack. When an item sells, payout is calculated automatically based on the agreed split — no manual math, no spreadsheet reconciliation. You get a clear record of what each consignor is owed and what’s been paid out.
When an item comes in, StackKnack pulls recent sold comps and suggests a price range — right at intake. You see the data behind the recommendation and can override it at any time. For aging inventory, StackKnack flags items that are sitting too long and shows the exact markdown needed to move them, including the payout impact on the consignor before you decide. Nothing is auto-applied without your approval.
Yes. StackKnack tracks inventory across multiple physical locations in one view. Staff at each location see what’s at their store; you see everything. No more texting between locations to confirm stock.
When a customer browses and leaves without buying, your staff logs what they were interested in — size, brand, specific item. StackKnack aggregates that data across your floor, matches it against comp trends, and surfaces what’s worth sourcing. You can also send targeted follow-up emails automatically when a matching item comes in. It turns foot traffic into a buying signal, not just lost sales.
Most operations are up and running in under an hour. We help you configure consignor commission structures, connect your sales channels, and verify inventory accuracy before you go live. Hands-on from day one.
Pricing is scoped to your operation — number of locations, consignors, and active SKUs all factor in. Book a 30-minute call and we’ll give you a specific number based on how you actually run. Most operations have a clear fit within the first conversation.
Yes. You can assign roles so floor staff can view and sell inventory while managers retain full edit and reporting access. Every change is logged with a full audit trail, so you always know who did what.
See what proactive intelligence looks like for your operation.
In 30 minutes we’ll show you pricing at intake, aging alerts in action, and automated consignor payouts — walked through your specific operation, not a generic demo.
30-min walkthrough · Pricing at intake · Aging alerts · Live in under an hour