Walmart Marketplace API integration: what we build and how it connects
Updated · By Ecomsellertool editorial team
A Walmart Marketplace API integration connects your Walmart seller account to Amazon, Shopify, a 3PL or an ERP. It moves items, prices, stock and orders through Walmart's APIs on 15-minute OAuth 2.0 access tokens, inside Walmart's per-seller rate limits. We build it as a direct integration on your own Walmart account and keys; our build notes come from IVCSR, a system we built across Amazon and Walmart.
- Walmart stopped the creation of new Delegated Access keys on July 30, 2026, and says existing keys work only until the end of September 2026 (Walmart Developer Portal, checked September 25, 2026).
- Walmart access tokens last 15 minutes. A refresh token from the OAuth 2.0 authorization code flow lasts one year; a seller's own client-credentials token comes with none.
- Walmart sets rate limits per seller, and separately per approved provider app: by default, single-item price updates allow 100 calls an hour, and order acknowledge, ship, cancel and refund calls allow 60 a minute each.
- One bulk item feed takes up to 10,000 items. Walmart suggests polling its status after 15 minutes, 1 hour and 2 hours, then every 4 hours.
- For IVCSR (Innovative Digital Sales) we built Walmart item setup and retirement, price and inventory updates, order acknowledgment and order-line updates, and Walmart Connect ad reporting next to Amazon.
- We are not on Walmart's list of approved Solution Providers. We build integrations that run on the brand's own Walmart account and API keys.
What syncs with Walmart Marketplace API
| What syncs | Direction | What starts it |
|---|---|---|
| Orders (the all-orders list) | Walmart to Growth OS | A scheduled pull that pages through Walmart's order list |
| Order acknowledgment, shipping and tracking | Growth OS to Walmart | When an order is accepted, then when the warehouse or 3PL confirms shipment |
| Order-line cancellations and refunds | Growth OS to Walmart | When a person on your team cancels or refunds a line |
| New items and item updates (bulk item feed) | Growth OS to Walmart | When a listing is approved to publish; the feed status is then polled until it is processed |
| Item retirement | Growth OS to Walmart | When a person retires a SKU |
| Prices | Growth OS to Walmart | An approved price change, batched to fit Walmart's hourly price limits |
| Inventory quantities | Growth OS to Walmart | A stock change, sent for changed SKUs only within Walmart's per-minute limit |
| Walmart Connect ad campaign reports | Walmart to Growth OS | A scheduled report pull |
Shipped in: IVCSR: Amazon and Walmart sales platform
This page is for brands and agencies that need Walmart connected to Amazon, Shopify, a 3PL or an ERP, and want to know what the build involves before they talk to anyone. It covers what the API can do, the API areas we have built against and what each one taught us, how authorization works now that Walmart has retired Delegated Access, the errors a broken connection shows, and what drives cost. Walmart facts link to Walmart's own documentation, checked September 25, 2026.
What can a Walmart Marketplace API integration do?
It takes over the routine catalog, stock, price and order work that otherwise happens by hand in Seller Center. Walmart groups its Marketplace APIs into OAuth scopes, and a seller reviews and approves a set of them when an App Store app connects. Walmart's list of API scopes tells approved Solution Providers to request only the minimum they need (checked September 25, 2026). The scopes that matter for most brands:
| Scope | What Walmart says it covers | What a brand usually uses it for |
|---|---|---|
| Items | Creating and managing items and lag time, including the bulk item, retire and delete feeds | Publishing the catalog from one product record |
| Inventory | Updating and querying inventory counts, by SKU and by ship node | Sending stock from one shared pool so Walmart does not sell what you do not have |
| Pricing and Promotions | Prices, promotions and repricing rules | Pushing prices set from cost, fees and your other channels |
| Orders | Order retrieval and acknowledgment on Walmart's orders resource | Getting orders to the warehouse or 3PL and tracking back to Walmart |
| Returns | Return requests, refunds and item-level return rule overrides | Closing returns in the same place as the order |
| WFS | For WFS sellers only: carrier and tracking information on Walmart's fulfillment resources | Shipments into Walmart's fulfillment centers |
| Analytics | Performance and listing reports, insights, and search engine marketing campaigns on Google Shopping | Sales, listing quality and seller performance next to Amazon |
Walmart also lists Account Profile and Shipping scopes, for store settings and shipping rules. Scopes limit App Store apps, not a seller's own keys: Walmart's OAuth FAQ says seller credentials grant full access to every API call (checked September 25, 2026). A direct integration therefore runs with more reach than any scoped app, and its keys deserve the care you give an admin password. The key-handling notes further down cover who stores and resets them.
An integration does not change what Walmart asks of a seller. If you are still deciding whether to sell there at all, our guide to selling on Walmart as an Amazon brand covers fees, WFS versus a 3PL or MCF, listing rules and how long onboarding takes. This page is about the connection itself: what moves, in which direction, what starts each sync and which limits it runs under.
Which Walmart APIs have we built against?
Our Walmart build notes come from IVCSR (Innovative Digital Sales), a system we built for a company that connects manufacturers with major US retail and ecommerce accounts. It brings Amazon and Walmart sales, orders, catalog and advertising data into one interface for several users, with rule management on top. The case study says Walmart's specific modules posed the main challenges. The table lists only the API areas that build used, with Walmart's default limit for each from its rate limiting page (updated August 31, 2026; checked September 25, 2026), and the note we would pass to anyone building the same thing.
| API area | What we built for IVCSR | Walmart's default limit | Build note |
|---|---|---|---|
| Items | New items through the bulk item setup feed (MP_ITEM) and updates to existing items, including variants, swatches and SKU or product ID overrides | MP_ITEM feeds: 10 an hour, up to 25 MB and 10,000 items each | A feed returns a feed ID, not a result. Poll it and send each item's errors to a fix queue |
| Item retirement | Retiring an item by SKU | 900 calls a minute | Walmart can take up to 48 hours to update the catalog. URL-encode SKUs that contain characters such as /, # or % |
| Feed status | All feed statuses and feed item status | 5,000 calls a minute, shared between the two | "Processed" means the feed finished, not that every item passed. Read each item's status: an item in GTIN exemption review can stay in progress after its feed is processed |
| Prices | Single-item price updates | 100 calls an hour; bulk price feeds 10 an hour, shared with promotional prices | At 100 calls an hour, 5,000 single-item changes take 50 hours. Batch large changes into feeds |
| Inventory | Quantity updates alongside item changes | 200 calls a minute; the inventory feed 10 an hour | Send only the SKUs that changed, and hold a buffer so a late update does not become a cancellation |
| Orders | The all-orders list | 5,000 calls a minute; released orders 60 a minute | By default, released orders are seller-fulfilled orders in Created status: at most 10,000 at a time, from the last 180 days |
| Order updates | Acknowledging orders, then shipping, canceling and refunding order lines | 60 calls a minute for each | Track status per line, because one purchase order can hold shipped, canceled and refunded lines at once |
| Advertising | Walmart Connect campaigns and reports: ad group, ad item, keyword, placement, search impression, out-of-budget recommendations and video | A separate API with separate access | Confirm the access route before scoping: see the note below |
Several of those notes come straight from Walmart's own guides. The bulk item setup guide caps a feed at 10,000 items, and the feeds overview suggests polling an item feed after 15 minutes, 1 hour and 2 hours, then every 4 hours. Walmart's Retire an item guide puts the catalog update at up to 48 hours. The released orders guide says WFS orders move to Acknowledged automatically and never appear in that list, so an integration that reads only released orders misses them (all checked September 25, 2026).
The advertising note matters before anyone quotes you a price. Walmart says its Walmart Connect ads APIs are available exclusively to Walmart Connect Partner Network partners (checked September 25, 2026). Whether a new build can read or change your Walmart campaigns depends on whose access it runs under: yours, your ad agency's or a partner tool's. We settle that in scoping, not after the build has started.
Some areas are not in a published build of ours: Walmart's separate Returns API for return orders, refunds and return rule overrides; WFS inbound shipments and WFS stock; stock by ship node from the Inventory API; offers matched to existing catalog items (MP_ITEM_MATCH); and webhook notifications (checked September 25, 2026). They rely on the same token handling, error queues and rate-limit discipline as the table above. We scope them per project and will not call them shipped until a case study shows them.
How does OAuth 2.0 authorization work after the Delegated Access retirement?
Walmart's Delegated Access notice says approved Solution Providers could no longer create new Delegated Access keys from July 30, 2026, and that existing keys work only until the end of September 2026 (checked September 25, 2026). Two routes remain. Walmart's guide for sellers offers a direct API integration with the seller's own keys, or a connection to an approved Solution Provider through the App Store in Seller Center. Walmart's Token API guide sets the token rules for both (checked September 25, 2026).
| Route | Who uses it | How it gets a token | What it can reach | Token lifetime |
|---|---|---|---|---|
| Direct API integration | The seller's own integration, including one we build to run on your account | Client credentials: the seller's Client ID and Client Secret | Every API: Walmart says seller credentials grant full access | Access token 15 minutes; no refresh token, so request a new one |
| App Store app (OAuth 2.0) | Companies Walmart has approved as Solution Providers, publishing one app for many sellers | Authorization code, exchanged for tokens | The scopes the seller approved | Access token 15 minutes; refresh token one year |
| Delegated Access key | Older provider connections | A separate Client ID and Secret per provider | The permissions the seller set for that provider | Stops working after September 2026 |
For an App Store app, Walmart's OAuth 2.0 authorization guide describes this flow (checked September 25, 2026):
- The seller selects Connect on the app in Seller Center, and Walmart opens the app's login URL with a
walmartCallbackUriparameter. - The app sends the seller to
login.account.wal-mart.com/authorizewithresponseType=code, itsclientId, itsredirectUri,clientType=sellerfor the US, a one-timenonceand astatevalue. - The seller signs in to Seller Center, reviews the permissions and selects Authorize.
- Walmart redirects to the app's callback with a
code, thesellerIdand the samestate. The app checks thatstatematches and stores thesellerId. - The app exchanges the code at
marketplace.walmartapis.com/v3/tokenfor a 15-minute access token and a refresh token that lasts one year. - Every API call carries the access token in the
WM_SEC.ACCESS_TOKENheader, and the app refreshes the token before it expires.
What a sound App Store build adds around that flow: refresh tokens stored per sellerId and kept out of logs; an access-token refresh well inside the 15 minutes, so a burst of calls never runs on an expired token; an alert weeks before a one-year refresh token runs out; and the smallest set of scopes that covers the job. Rate limits follow the route. Walmart's rate limiting page says a seller's direct calls do not count against an approved provider's allowance, and each provider app gets its own, so a direct integration does not eat into the allowance of apps you already connected. For the seller's side of reconnecting existing apps, see our Walmart OAuth migration checklist.
What errors show up when a Walmart connection breaks?
Walmart does not say which error a retired Delegated Access key returns. Its authentication FAQ, its rate limiting page and its feeds overview explain the codes a sync log shows when access, permissions or volume go wrong (checked September 25, 2026). Our reading, not Walmart's: if a connection that was never moved to OAuth starts logging 401 or 403 errors from October 1, 2026, the retired key is the likely cause.
| What the log shows | What Walmart says it means | What to check first |
|---|---|---|
| 401 Unauthorized | The access token is missing, malformed, expired or from the other environment | Is the token refreshed before 15 minutes? Is a sandbox token hitting production? Is this connection still on a Delegated Access key? |
| 403 Forbidden | The token is valid but lacks permission for that call | Does the authorization include the scope, such as Items, Orders or Inventory? |
| 429 Too Many Requests | The rate limit for that API is used up | Read x-current-token-count and X-Next-Replenishment-Time, then retry with exponential backoff and jitter |
| 413 Payload Too Large | The feed file is over the size limit for its type | Split the file into smaller feeds |
| Feed status ERROR | The whole feed failed and no items were processed | The feed type and file format |
| Item DATA_ERROR | The item's data is invalid or required data is missing | Fix the record and resubmit that item |
| Item SYSTEM_ERROR or TIMEOUT_ERROR | A downstream Walmart system returned an error or was unavailable | Wait at least an hour, retry, then contact Walmart Partner Support |
The costliest failure has no error code at all: a scheduled job that stops running while Walmart keeps taking orders. Walmart's OAuth FAQ says seller credentials are shared by all users on the account and tells sellers who see "unauthorized" errors to make sure another user has not reset the keys (checked September 25, 2026). A reset cuts off every integration still using the old pair. A sound build alerts on silence as well as on errors: Walmart items still published, but no orders imported for longer than your slowest selling hours.
How does Walmart connect to Amazon, Shopify and your 3PL?
Through one product record and one stock pool, with Walmart as one more channel rather than a separate operation. Each step below maps to a row of the What syncs table above and to the Walmart call behind it, and each has a person on your team who owns its exceptions. In the builds we deploy on Ecomsellertool Growth OS, the flow runs like this:
- One SKU map. Each product has one record that maps its Amazon ASIN, Shopify variant, 3PL item code and Walmart SKU, so a change is made once. You set the Walmart SKU, and it sits in the URL of calls such as item retirement, so a SKU containing
/,#or%has to be URL-encoded every time. - Items out. Walmart content is mapped to Walmart's product types and attributes, then sent in bulk item feeds, with each item's errors routed to a person.
- Stock out. Available stock from your warehouse, your 3PL and, if Walmart orders may ship through MCF, FBA is pooled. A buffer is held back, and only changed quantities go to Walmart.
- Orders in. Seller-fulfilled Walmart orders join Amazon and Shopify orders in one queue and are routed to the node that can ship them on time at the lowest cost. WFS orders need no routing and are read for reporting.
- Tracking back. When the warehouse or 3PL ships, the carrier and tracking number go back to Walmart on each order line.
- Reporting. Walmart sales, fees and ad spend sit next to Amazon's, per SKU.
If Walmart orders ship from FBA stock through Multi-Channel Fulfillment, the routing rule has to follow Amazon's guide to MCF for Walmart orders: blank packaging and Amazon Logistics blocked as a carrier. Amazon normally charges a 5% surcharge for blocking Amazon Logistics and has waived it until January 14, 2027 (checked September 25, 2026), which changes the cost comparison your routing rule makes. The Amazon half of the system runs on the Selling Partner API, and our Amazon SP-API development page covers that side.
Order dashboard across every connected marketplace
Read the Seller7 case study ↗The screen above is the order dashboard we built for Seller7, a multi-marketplace seller OS, across every connected marketplace, Walmart included. It shows the shape of the order side, not a result: each order keeps its marketplace, its status and the action waiting on it, whichever channel it came from.
A custom build is not always the right call. Shopify Marketplace Connect syncs listings, orders and inventory between Shopify and Amazon, Target Plus, eBay and Walmart; it lists the first 50 synced orders a month as free, then a 1% fee per synced order, capped at $99 a month (checked September 25, 2026). Amazon's new multichannel tools in Seller Central connect Walmart accounts, import listings and show orders, rolling out gradually to US sellers at no added cost (checked September 25, 2026). Walmart's Solution Provider Hub lists solution providers and agencies that work with Walmart sellers.
If one of them covers your flows, use it: an app you can switch on this week usually costs less than a build. Check three things first: whether it sends stock from every location you ship from, whether it follows your order routing rules, and whether its data reaches your reporting. A custom integration makes sense when your stock sits in several places, your rules differ by channel or SKU, or Walmart has to talk to an ERP, 3PL or reporting stack an app does not reach.
What does a Walmart integration cost and take?
It depends on how many API areas you need, and whether the integration only reads data or also writes prices, stock, items and order updates back to Walmart. We do not publish a price list. Our SP-API development cost guide describes what drives cost on Amazon builds; it is our experience, not a price list, and most of those drivers apply to Walmart too. Custom modules and AI agents are scoped in an architecture doc with a fixed price and go-live date, which you approve before work starts.
| What you need | What it adds to the build |
|---|---|
| Reporting only: orders, items and ad reports into your dashboards | Scheduled pulls, pagination and storage. The smallest scope |
| Prices and stock written back to Walmart | Queues and batching inside Walmart's hourly and per-minute limits, buffers, and a change log |
| New items and content updates | Mapping your catalog to Walmart's product types and attributes, which is usually the largest single task, plus a feed error queue |
| Order acknowledgment, shipping, cancellations and refunds | Line-level order states, carrier names Walmart accepts, and routing to your 3PL or MCF |
| WFS | WFS orders read from the all-orders list, plus separate endpoints for WFS stock and inbound shipments |
| Walmart Connect advertising | An access route through the Walmart Connect Partner Network, settled before the build |
| An App Store app for many sellers | Walmart's approval, the OAuth 2.0 code flow and a demo to Walmart |
Walmart's approval steps add time only on the App Store route: its guide for Solution Providers says approval and publication can take three to five weeks, with a demo before an app is published (checked September 25, 2026). A direct integration on your own account skips that. Either way, a new build should prove its order and stock flows in Walmart's dynamic sandbox, a US-only test environment with its own base URL and credentials where you can place, ship and return test orders without touching Seller Center or live orders (checked September 25, 2026).
What to have ready before a scoping call
- The person with admin access to your Walmart Developer Portal keys, and a list of every tool that uses them today
- Your SKU list with the matching Amazon ASINs and Shopify variants, flagging SKUs that contain
/,#or% - Every location that ships Walmart orders: your warehouse, each 3PL, FBA through MCF, and WFS
- Which flows must write back to Walmart (prices, stock, items, order updates) and which only feed reporting
- Whether you or your ad agency already has Walmart Connect API access through the Partner Network
Who builds custom Walmart Marketplace API integrations?
Ecomsellertool is a tech agency that builds marketplace integrations and operations software on brands' own accounts. We have built on Amazon's seller APIs since 2017 and shipped integrations for 20+ marketplaces, Walmart among them. For a Walmart integration, we map your catalog, wire items, prices, stock and orders to Amazon, Shopify and your 3PL, and hand your team the queues for the exceptions.
We are not on Walmart's list of approved Solution Providers and have no App Store app of our own. What we build runs as a direct integration on your Walmart account, deployed with Growth OS on your own accounts. Because your seller keys grant full API access, we agree with your admin during scoping where they are stored and who may reset them. You keep your accounts, your data and the custom code we build; the Growth OS base is licensed to you. If you stop working with us, your accounts, data and custom code stay with you; the Growth OS base continues under its license terms.
Walmart is usually one part of a wider marketplace expansion, and the other integrations we have shipped are on the integrations hub. If you want to talk through your Walmart flows with the engineers who would build them, schedule a call from the card below. If Amazon is your main channel, the free 24-hour diagnostic connects through Login with Amazon, with no password shared, and reports within 24 hours of connecting, on business days. We only read data; we never change listings, prices, stock or ads.
Frequently asked questions
Does the company building our Walmart integration need to be an approved Solution Provider?
No, not for an integration that serves only your own account. Walmart's getting-started guide for sellers offers a direct API integration that runs on your own Client ID and Client Secret. The approved Solution Provider route is for companies that publish one app for many sellers in the Walmart App Store, and Walmart says approval and publication can take three to five weeks, with a demo before the app goes live.
Can one integration handle both seller-fulfilled and WFS items?
Yes, but the two behave differently. Walmart acknowledges WFS orders automatically, so they never appear in the released-orders list that seller-fulfilled orders come from; Walmart says to read them from the all-orders or single-order endpoint instead. WFS stock and inbound shipments use their own endpoints, which we scope separately because they are not in a published build of ours.
How do you test a Walmart integration without touching live orders?
Walmart runs a dynamic sandbox for the US marketplace, with its own credentials, its own base URL (sandbox.walmartapis.com) and a WM_SANDBOX: v2 header. It lets you create test items and inventory, place a test order, then acknowledge, ship and deliver it, and start a return and a refund, without affecting Seller Center or Walmart.com. That is where a new build should prove its order and inventory flows before it runs on production keys.
What happens if someone resets our Walmart API keys?
Every integration that uses that key pair stops until it gets the new credentials. Walmart's FAQ says seller credentials are shared by all users on the account and that resetting them needs admin access. Agree on who may reset keys, and tell your integrator before you do it, so the new pair goes in before the next scheduled order pull.
What happens to the integration if we stop working with you?
You keep your accounts, your data and the custom code we build; the Growth OS base is licensed to you. The integration runs on your Walmart account and your API keys, so the connection and its data stay on your side. If you stop working with us, your accounts, data and custom code stay with you; the Growth OS base continues under its license terms.
Can Walmart send us events instead of us polling for changes?
For some events, yes. Walmart's notifications send a webhook to a URL you choose when, for example, a new order is created, an item is unpublished or stock runs out, and Walmart describes them as a way to poll less within the rate limits. We treat a webhook as a prompt to check, keep a scheduled pull as the backstop, and decide per flow during scoping which events to subscribe to.
