Shopify → eBay DE → eBay US
Sell it once.
It’s gone everywhere.
WonderSync is Shopify eBay inventory sync for quantity-1 sellers. Cross-list your Shopify catalogue to eBay DE and eBay US — and the second something sells on any channel, every other listing comes down.
Free forever for 25 cross-listed products · no card required
| SKU | Channel | Status |
|---|---|---|
| JKT-041-de | eBay DE | SOLD |
| JKT-041 | Shopify | ENDED |
| JKT-041 | eBay US | ENDED |
10s
how often the delist queue drains — around the clock, every day, whether or not you are watching.
Syncs across
Shopify · eBay.de · eBay.com
01 — Import
Your Shopify catalogue, listed in two clicks
Pull your products in, tick the ones to cross-list, and WonderSync takes it from there. Condition is inferred from the tags you already use. Photos are never copied — eBay ingests them straight from the Shopify CDN, so your images live in exactly one place and never drift.
Refreshing re-syncs price, quantity and title for anything not yet listed, so edits in Shopify stay the source of truth.
- Vintage Levi’s 501 · straightJKT-041 · qty 1€89.00
- Wool overcoat · charcoalCOAT-112 · qty 1€140.00
- Silk scarf · botanical printSCF-903 · qty 1€35.00
- Leather satchel · tanBAG-220 · qty 1€120.00
- tag: RedFarbe: Rot
- option: Size MGröße: M
- vendor: Levi’sMarke: Levi’s
- type: Women’s JacketAbteilung: Damen
- 65% polyester, 35% cottonMaterial: Polyester
02 — Publish
How does WonderSync fill eBay Germany’s item specifics?
It fetches the live required aspects for the eBay category, then maps your English Shopify data onto the German field names — Marke, Größe, Farbe, Abteilung and around twenty more. Values are translated too, so a product tagged “Red” satisfies a Farbe field that only accepts “Rot”.
It never invents a value. Selection-only fields are filled only when your data genuinely matches one of eBay’s allowed options, and anything left unmatchable stops the publish and names the exact field to fill. That is the difference between a listing that goes live and one that gets pulled.
- Marketplaces
- 2
- from one Shopify product
- US price factor
- ×1.1
- default, configurable
03 — The cascade
What happens the moment something sells?
The sale is claimed by a single atomic database update, so exactly one channel can ever win it. Delist jobs for every other live listing are committed in that same transaction, then drained by a queue that runs every 10 seconds. In practice the other listings are gone in about two seconds.
14:02:11Sale detected
eBay.de · order 14-09832-771 · SKU JKT-041-de
14:02:11Claim won
one atomic update · exactly one winner, ever
14:02:12Shopify delisted
inventory set to 0 · product archived · 1.4s
14:02:13eBay US withdrawn
offer withdrawn · idempotent · 2.1s
14:02:13Product closed
0 channels live · oversells 0
two seconds, start to finish
04 — Failure
What happens when a delist fails?
It retries with exponential backoff — 2, 4, 8, 16, 32, 64, 120 seconds — for retryable errors only. If the marketplace still refuses, WonderSync raises its loudest alert and deliberately leaves the listing live in its records, so the sweep keeps re-detecting it until it is genuinely gone.
Most sync tools are built for the happy path. This one is built for the moment two buyers hit “buy” at once, and for the 3am eBay outage that nobody is awake to see. Nothing is marked done and forgotten.
- A failed poll never advances its cursor, so no sale window is silently skipped.
- Every poll re-scans a 10-minute overlap window behind its cursor.
- A genuine oversell raises a critical alert naming the exact order to cancel — never a silent drop.
- 012s
- 024s
- 038s
- 0416s
- 0532s
- 0664s
- 07120s
How it works
How does Shopify eBay inventory sync work?
Connect your Shopify store and eBay account, import the products you want cross-listed, and publish them to eBay DE and eBay US. WonderSync then watches all three channels. When an item sells on one, it claims the sale and removes the listing from the others automatically.
- 01
Connect Shopify and eBay
Paste a Shopify custom app token and sign in to eBay once. WonderSync verifies the shop, registers the order webhook, and encrypts both credential sets with AES-256-GCM.
- 02
Import the products you want listed
Pull your Shopify catalogue and tick the items to cross-list. Photos stay on the Shopify CDN and condition is inferred from your existing tags.
- 03
Publish to eBay DE and eBay US
WonderSync suggests the eBay category, fetches its live required aspects, and fills the German item specifics from your English data. One product becomes two listings, priced per marketplace.
- 04
Sell on any channel
A Shopify sale arrives by webhook in seconds; an eBay sale is caught by the 60-second poll. Both funnel into one atomic claim that decides the winner exactly once.
- 05
Every other listing comes down
Delist jobs are committed in the same transaction as the claim and drain on a 10-second queue. A 10-minute sweep independently re-checks every live listing against the marketplace itself.
From the build
“Overselling isn’t prevented by trying harder. It’s prevented by making it impossible for two sales to both win — one conditional update, one winner, decided by the database rather than by hope.”
process_sale_eventPricing
How much does WonderSync cost?
Basic is free forever and covers 25 cross-listed products with no card. Premium is €29 a month for 250 products, Enterprise is €99 a month for unlimited. Every plan gets the full sync engine — the tiers only change how many products you can cross-list at once.
Basic
Freeforever
For testing the sync on a real rack.
- 25 cross-listed products
- eBay DE + eBay US from one Shopify catalogue
- All 3 sale-detection layers
- Oversell checklist and critical alerts
Premium
€29per month
For sellers running a full rack across both marketplaces.
- 250 cross-listed products
- Everything in Basic
- Team members with roles
- Per-marketplace business policies
Enterprise
€99per month
For catalogues that outgrew a number.
- Unlimited cross-listed products
- Everything in Premium
- Priority on publish and delist queues
- Direct line for marketplace edge cases
Free forever for 25 cross-listed products · no card required. Prices exclude VAT, which is calculated at checkout for your country. Paid plans are month-to-month — cancel in the billing portal any time and drop back to Basic without losing your data.
Guides
Learn the workflow first
- How to sync Shopify inventory to eBayA step-by-step guide to syncing Shopify inventory with eBay DE and eBay US, including how to keep stock levels accurate and stop overselling one-off items.6 min read
- How to avoid overselling across marketplacesWhy overselling happens when you sell the same stock on Shopify and eBay, what it costs you, and the four mechanisms that actually prevent it.5 min read
- How to list Shopify products on eBay.deWhat eBay Germany requires that eBay US does not — German item specifics, EUR pricing, business policies — and how to fill them from English Shopify data.6 min read
FAQ
Questions resellers actually ask
What is WonderSync?
WonderSync is Shopify-to-eBay inventory sync software for quantity-1 sellers: it cross-lists your Shopify catalogue to eBay DE and eBay US, and the moment an item sells on any channel it delists the item everywhere else. It is built for quantity-1 sellers — vintage, secondhand and one-off stock — where a single oversell means cancelling on a real buyer.
How much does WonderSync cost?
Basic is free forever and covers 25 cross-listed products with no card required. Premium is €29 per month for 250 products, and Enterprise is €99 per month for unlimited products. Prices are shown excluding VAT, which is added at checkout based on your country.
How fast does WonderSync delist a sold item?
A sale on Shopify arrives by webhook and the other listings come down within seconds. A sale on eBay DE or eBay US is caught by a poll that runs every 60 seconds, so worst case is under a minute. The delist queue itself runs every 10 seconds around the clock, and the detecting request also kicks the queue immediately.
Can I still oversell with WonderSync?
If two buyers genuinely pay at the same instant on two marketplaces, no software can un-take their money. What WonderSync guarantees is that it never happens silently: exactly one channel wins the item in a single atomic database update, and the losing order lands on a red oversell checklist naming the exact order to cancel. It stays there until you resolve it.
Which marketplaces does WonderSync support?
Shopify as the source of truth, cross-listing to eBay Germany (ebay.de) and eBay US (ebay.com). Those three channels are what the product supports today. The channel model is built so more marketplaces can be added.
How does WonderSync fill eBay Germany’s required item specifics?
WonderSync fetches the live required aspects for the target eBay category and maps your English Shopify data onto them, including the German field names — Marke, Größe, Farbe, Abteilung and around twenty more. Values are translated too, so a product tagged “Red” satisfies eBay.de’s “Farbe: Rot”. It never invents a value: anything genuinely unmatchable is surfaced as a missing required field before publish, naming the exact eBay field to fill.
Do I need to re-upload my product photos to eBay?
No. eBay ingests images directly from the Shopify CDN, so your photos live in exactly one place and never drift out of date. There is no image storage bill and no re-upload step when you edit a product in Shopify.
What access does WonderSync need, and how are my credentials stored?
A Shopify custom app token with product, inventory and order scopes, plus an eBay sign-in covering ebay.de and ebay.com. Credentials are encrypted at rest with AES-256-GCM and are never displayed again after saving. Data lives in a Supabase Postgres project in the EU (Frankfurt) with row-level security isolating every account.
What happens if a delist fails while I am asleep?
It retries with exponential backoff — 2, 4, 8, 16, 32, 64, 120 seconds — and if the marketplace keeps refusing, WonderSync raises a critical alert telling you to end the listing manually. The listing is deliberately left live in our records so the 10-minute reconciliation sweep keeps re-detecting it and re-queuing the delist until it is genuinely gone.
Can I cancel anytime?
Yes. Paid plans are month-to-month through Stripe, and you can cancel or change plan yourself in the billing portal at any time. Cancelling drops you back to the free Basic tier rather than locking you out of your data.
Your inventory, everywhere.
Your oversells, nowhere.
Connect Shopify and eBay, import your rack, and let the sync engine watch every channel — around the clock, on a 10-second beat.
Start syncing freeFree forever for 25 cross-listed products · no card required