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Square POS integration for ecommerce and retail operations

Sync branch, online and ERP in step reliably. Square POS connects your till, ecommerce, stock and customer data so branch transactions and online orders stay aligned. Stock, pricing, loyalty and refunds flow without silos. Works with Adobe Commerce, Magento Open Source, Shopify Plus, BigCommerce and other storefronts.

Also searched as: EPOS, till system, retail POS, branch system, trade counter system.

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Works with - Magento Open Source · Adobe Commerce · Shopify Plus · BigCommerce · Other storefronts
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01 · What you get

What a Square POS integration gives you.

Branch and online stock stays in step

Stock counts, reservations and adjustments flow between the till and ecommerce without double-selling across channels. Shoppers see true availability whether they shop online or in-store.

Pricing is consistent in-store and online

Promotions, local overrides and bulk discounts ring correctly at the till and display online. Branch pricing rules no longer conflict with ecommerce pricing feeds.

Click-and-collect works reliably

Online orders mark as ready to collect at the branch, staff pick them, and the shopper collects without confusion. Returns and uncollected orders automatically update stock and customer records.

Customer loyalty and credit work across channels

A loyalty member accumulates points in-store or online and redeems them either way. Trade account credit limits and status are visible to both till and ecommerce so staff can process accurately.

Finance reconciliation is trustworthy

Till transactions flow into ERP, matching bank deposits and revenue lines. Multi-location reconciliation no longer relies on manual spot-checks and end-of-period corrections.

02 · When it's worth it

Where a Square POS integration earns its place.

If two or more of these are true, the integration usually pays for itself quickly.

Branch stock visibility from till into ecommerce and central inventory
Sync customer accounts and loyalty across in-store and online
Click-and-collect order handoff from ecommerce to branch till
Branch pricing overrides and trade account rules in till reconciliation
In-store transactions feeding into central ERP and finance
Offline till operation with deferred sync to ecommerce and stock system
03 · The limits

Where off-the-shelf connectors fall short.

Vendor connectors are fine for simple cases. Here's where the real ones need more.

No native ecommerce-to-till bridge

Square POS does not natively sync click-and-collect orders, online pricing updates or real-time stock visibility from a separate ecommerce platform. Manual processes or third-party connectors are often needed.

Limited ERP and stock-system integration

Square can track till transactions but lacks deep integration with central ERP systems for GL posting, cost accounting, stock revaluation and multi-location allocation without custom work.

Customer and loyalty data silos

Customer records and loyalty balances live in Square's CRM or loyalty module. Syncing them reliably with ecommerce customer bases and CRM platforms requires manual exports or API work.

Offline till operation complexity

When internet connectivity drops, Square can take payments offline but reconciling transactions, stock movements and customer changes after reconnection is not automatic and can leave gaps.

Inventory visibility not real-time across channels

Stock held in Square reflects till activity but linking it to ecommerce inventory and preventing oversell across in-store and online requires a connecting layer to watch both systems continuously.

04 · The real work

Branch and online operations collide when stock, pricing and customer data are not kept in step; offline till operation and fast inventory changes can leave data in multiple places with no clear owner.

05 · Where it sits

Where this integration sits in your estate.

Square POS holds the commercial record. The iWeb integration layer manages the rules, mappings, monitoring and exceptions. The commerce platform presents the customer-facing experience. The estate map helps agree ownership before anything is built.

No platform lock-in. We integrate Square POS with the commerce core you already have, or the one you are moving to.

System of record
Source / owner
Square POS
Branch till and retail-operations system; feeds inventory, revenue, customer and loyalty data to central systems.
  • Till transactions and receipts
  • Branch-local stock movements and adjustments
  • In-store customer interactions and updates
  • Loyalty earn and redemption at till
  • Offline payment capture during connectivity loss
iWeb integration layer
Customer-facing commerce
Commerce platform
Magento Open SourceAdobe CommerceShopify PlusBigCommerceOther storefronts
  • Product catalogue and descriptions
  • Online pricing and promotions display
  • Ecommerce customer account records
  • Shopping cart and checkout
  • Click-and-collect order placement
Connected neighbours
Integration layer
ERP / Finance
Till transactions post to ERP for GL, cost accounting and stock revaluation. Multi-location allocation and month-end reconciliation happen in ERP.
Integration layer
Stock / Inventory System
Central system of record for stock across all locations and channels. Till and ecommerce both read and write stock via the connector.
Integration layer
Customer CRM / Loyalty
Customer accounts, credit limits, loyalty balances and preferences live here. Till and ecommerce sync customer events bidirectionally.
Integration layer
Order Management (OMS)
Handles click-and-collect order routing to the branch and fulfillment status back to ecommerce and customer service.
Integration layer
Payments and Bank
Authorises till transactions, handles captured payments and feeds reconciliation files to accounting for bank matching.
Two-way sync where relevant
06 · Surrounding systems

Systems this integration usually sits next to.

Examples, not a closed list. iWeb is platform-agnostic on both sides: we wire this integration into whatever ecommerce platform and surrounding systems your estate already runs.

Ecommerce platforms (examples)
  • Magento Open Source
  • Adobe Commerce
  • Shopify Plus
  • BigCommerce
  • Other storefronts
Surrounding systems (examples)
  • ERP (SAP, Oracle, NetSuite)
  • Central stock and inventory system
  • OMS (order management and orchestration)
  • Customer CRM and loyalty platform
  • Accounting and finance ledger
  • Reporting and BI warehouse
  • Payment processor and bank reconciliation
Not sure?

Not sure if this works with your stack?

Tell us what you’re using and what needs to connect. We’ll give you a straight view on what’s possible, what might be awkward, and the safest way to approach it.

07 · Data flows

The data flows we wire.

Each flow has a direction and an owner. We agree both before a line of code is written.

→Into TILL
←From TILL
↔BOTH WAYS
Branch stock and transaction data: Till transactions, stock movements, refunds and voids flow out of Square into ERP, accounting and central stock systems
Branch stock counts need to reconcile with ecommerce availability to prevent oversell.
Pricing, promotions and product changes: Price changes, promotions, product updates and catalogues flow from ecommerce or ERP into Square so the till always rings the right total and customers see consistent offers in-store.
Customer account and loyalty data: Customer records, loyalty balances and account status sync between the till, ecommerce and CRM
A shopper who builds credit or earns points in-store should see the same balance online.
Click-and-collect order instructions: Online orders marked for in-store pickup route to the branch till as collect-ready notifications
Branch staff pick and hold stock, then notify the shopper and ring the sale when they arrive.
Branch and online returns and refunds: Returns initiated online or at the till need to reconcile across both channels, update stock and flow back to finance
A customer should be able to return an online purchase at the branch without a second receipt.
08 · How we build it

How iWeb configures the integration around your business.

Same method on every integration. The decisions come before the code.

  1. 01
    Design the integration ownership map

    iWeb names which system owns stock, pricing, customer records and loyalty state. This removes ambiguity so branch staff, ecommerce teams and finance all know where the truth lives and who updates it.

  2. 02
    Build the data-movement layer

    iWeb constructs the connectors, transforms and APIs so till transactions, pricing, stock and customer data flow into and out of Square with the right timing and accuracy. Offline till operation is handled with clear reconciliation rules.

  3. 03
    Set up monitoring and exception handling

    iWeb configures alerting so failed syncs, stale stock, pricing mismatches and unreconciled refunds are surfaced immediately. Exception queues are owned and cleared so problems do not hide in logs.

  4. 04
    Support click-and-collect workflows

    iWeb designs the order flow from ecommerce into the till, how stock is reserved and released, and what happens if a customer doesn't collect. Staff training and runbooks cover the exceptions.

  5. 05
    Own the go-live and rollback

    iWeb tests parity between till, ecommerce, ERP and stock systems before launch. A clear rollback path exists so a failed sync can be reverted without leaving customers or finance confused.

09 · Ownership

Who owns what.

The single most important table in any integration. One system owns each field; everything else reads it.

Data
Source / owner
Maintained by
Notes
DataBranch stock levels and movements
Source / ownerERP or central stock system
Maintained bySquare till + stock system connector
NotesTill transactions adjust stock in real time; ecommerce reads central stock to prevent oversell; daily reconciliation feeds back to ERP.
DataLocal pricing and trade account overrides
Source / ownerERP or pricing engine
Maintained bySquare + ecommerce pricing sync
NotesBranch override rules are defined in ERP or Square, synced to ecommerce and till. Each channel rings the correct price; finance sees the cost basis.
DataCustomer accounts and credit limits
Source / ownerERP customer module or CRM
Maintained byTill + ecommerce + CRM sync
NotesCustomer master and credit status live in ERP or CRM. Till and ecommerce read customer and credit state; updates from either channel feed back to the source system.
DataLoyalty and points balance
Source / ownerSquare loyalty or CRM
Maintained byTill + ecommerce + CRM connector
NotesTill and ecommerce both record earn and redemption events. Balances sync back to Square loyalty or CRM so a customer sees the same points whether they transact in-store or online.
DataClick-and-collect order and pickup status
Source / ownerEcommerce OMS or order layer
Maintained byEcommerce + till + stock sync
NotesEcommerce creates the order; till receives pickup instruction; stock is reserved. Pickup or expiry events route back to ecommerce and trigger customer notifications.
DataTill transactions and refunds
Source / ownerSquare and ERP
Maintained bySquare + ERP accounting sync
NotesTill records the transaction; ERP journals the revenue and cost. Refunds and voids flow back into both systems. Reconciliation happens daily or batch-wise depending on ERP cycle.
DataIntegration transport and exception handling
Source / owneriWeb integration layer
Maintained byiWeb monitoring and alerting
NotesFailed syncs, stale stock, offline till reconciliation gaps and unmatched refunds are surfaced to named owners. Exception queues are cleared before closure.
10 · Experienced integrator

Built this integration pattern before

iWeb has integrated Square POS with ecommerce storefronts, central ERP systems and stock platforms on many occasions. We understand how till operation, offline resilience and multi-channel inventory challenges show up, and how to design integration ownership and exception handling so branch staff and finance teams trust the data.

Understands Square's offline-first architecture and how to reconcile till transactions, stock adjustments and refunds after reconnection without data loss.
Has designed click-and-collect workflows where ecommerce orders route cleanly to branch tills and stock is reserved, released and refunded on time.
Knows how to map branch pricing overrides, trade account discounts and local promotions so till rings correctly, ecommerce doesn't leak restricted pricing, and finance reconciles without confusion.
Can build reliable stock-parity and pricing-parity monitoring so oversell and pricing drift are caught and surfaced to named owners before they impact customers or revenue.
Has set up customer and loyalty data flows so account status, credit limits and loyalty points stay synchronized between till, ecommerce and CRM whether transactions happen in-store or online.
11 · Before launch

What we test before launch.

Every one of these is rehearsed before a customer ever sees the integration.

Test stock parity: sell an item at till and confirm ecommerce inventory decrements within SLA; repeat for ecommerce sale into till view.
Test click-and-collect end-to-end: order online, confirm order appears at branch till, pick and ring up, confirm ecommerce marked as collected.
Test offline till sync: disconnect internet, complete payments, verify transactions reconcile to ERP and stock systems after reconnection without duplication or gaps.
Test pricing and override: apply a branch-specific discount at till, confirm it rings correctly and does not leak to ecommerce; verify ERP sees correct revenue.
Test customer and loyalty: create account online, visit branch, confirm till recognizes customer and loyalty balance; earn points, check balance online.
Test refund and return flow: initiate return at till, confirm stock refunded, ecommerce order cancelled and refund posts to finance; repeat for online return at branch.
Test reconciliation reports: run daily or shift-end parity report comparing till, ecommerce and ERP; confirm any variance is flagged and owned within defined SLA.
12 · Failure points

Common risks and where they bite.

We name these on day one. A risk written down is a risk you can plan around.

Offline till transactions lost in reconciliation

When a branch goes offline and the till takes payments without internet, those transactions may not sync back cleanly. Stock, revenue, customer balance updates and refunds can end up in the wrong system or delayed.

Stock oversell across in-store and online

If till stock counts and ecommerce inventory do not sync frequently or continuously, an item can be sold twice - once at the till and once online for the same unit. Refunds and delivery failures follow.

Customer and loyalty data conflicts

A customer account created or updated in the till may not reconcile with the same customer in ecommerce or CRM. Loyalty balances can diverge, and credit limits become unreliable.

Pricing and promotion drift

Branch staff override prices at the till for trade account discounts or local promotions. If those overrides do not sync back to ecommerce or ERP, online customers see wrong prices and finance reconciliation fails.

Click-and-collect orders stuck between systems

An order marked for in-store pickup may not route cleanly to the till, or if it does, a customer who doesn't collect might not trigger an automatic stock release and refund. Manual intervention becomes the norm.

Finance reconciliation drift after peak trading

Multi-location till transactions, refunds, offline reversals and ERP accruals can diverge after a busy day. Month-end reconciliation becomes a painful manual review with no clear owner accountable for gaps.

13 · Where it applies

Relevant services and sectors.

14 · Questions

Common questions about Square POS integrations.

How do we prevent stock from being sold twice, once in-store and once online?

iWeb designs a reservation and sync pattern where stock is held in a central system (usually ERP or a dedicated stock engine). The till and ecommerce both read the same inventory in near real time. When either channel sells a unit, the others see the change immediately. Regular heartbeat syncs and exception alerts catch any drift.

What happens to till transactions if the branch goes offline?

Square POS can continue taking payments offline. Once the till reconnects, transactions sync back to Square's cloud and then to ERP and ecommerce. iWeb sets up reconciliation rules so stock, revenue, customer balance and refund records flow to the right systems in the right order without duplication.

How do click-and-collect orders flow from ecommerce to the branch till?

eCommerce marks an order as 'collect in store' and sends it to the till system, usually via Square's APIs or a middleware layer. The till receives a pickup notification, staff pick the order and place it in a collection area. When the customer arrives, staff scan or look up the order and ring it up, triggering a final ecommerce status update.

How do we keep customer accounts and loyalty points in sync across channels?

Customer records and loyalty balances live in Square, ecommerce or a shared CRM. iWeb sets up real-time or daily syncs so earn and redemption events from the till are reflected online and vice versa. If a customer creates an account online and visits the branch, the till recognizes them immediately.

Can the branch apply local pricing overrides at the till without breaking ecommerce?

Yes. iWeb maps branch override rules (e.g. trade-account discounts) to the ERP or Square. The till applies the override locally; the ecommerce storefront does not show a discounted price (unless the customer is logged into their account and entitled to it). Finance sees the correct revenue line and cost basis.

How does finance reconcile till transactions with online orders and ERP?

iWeb designs the journal flow so till transactions, refunds and online orders all post to ERP with the same account coding. A daily or shift-end reconciliation report shows what landed in Square, what posted to ERP and what is in flight. Named owners investigate any variance before month-end close.

What if a customer orders online for collection but never shows up?

iWeb sets an expiry rule: after a defined hold period (e.g. 5 days), the order automatically releases the reserved stock, cancels the ecommerce order, and initiates a refund. The till sees the collection order expire and removes it from the pickup list.

Can a customer return an online purchase at the branch till without a receipt?

If the customer account is linked across ecommerce and till, the till can look up the online order and process the return. The till records the refund, stock is credited back, and the customer's ecommerce account is updated. Finance sees the return in ERP.

How do we monitor if stock or pricing gets out of sync?

iWeb sets up scheduled reconciliation checks: e.g. every hour, compare till stock with ecommerce stock and flag any difference above a threshold. Daily price audits check if till and ecommerce are ringing the same cost. Alerts go to stock owners and merchandisers so they can investigate.

What happens if Square's API goes down during a busy trading day?

The till can continue taking payments offline. When connectivity returns, Square resyncs. iWeb sets up a clear protocol: once synced back to Square, transactions route to ERP and stock in the correct order. If any transaction failed to reconcile, an alert fires so operations can investigate before it impacts finance or stock.

Do we need a separate inventory system, or can Square be our stock engine?

Square can track till transactions and adjust inventory, but for a multi-location, multi-channel estate, a central ERP or stock system usually acts as system of record. Square feeds it. iWeb sets up the sync so ecommerce, till and ERP all read the same stock number, and updates cascade back reliably.

How do we handle branch-specific promotions that should not appear online?

iWeb maps promotion governance: branch promotions are defined in Square or ERP with a 'till only' flag. Ecommerce does not ingest them. Store staff communicate the in-store-only offer to shoppers. Finance sees all revenue and cost properly attributed.

What integration testing do we need before launch?

Test stock parity between till and ecommerce after a simulated sale. Test a click-and-collect order from ecommerce appearing at the till. Test an offline till transaction syncing back and appearing in ERP. Test a refund at the till appearing in ecommerce and finance. Test a new customer created at the till appearing online. Test pricing overrides ringing correctly and not showing online.

Who is accountable if a stock number or price diverges?

iWeb defines the ownership map before build starts. Usually: ERP owns stock and list price; till and ecommerce read it. If they diverge, the integration layer alerts the stock owner and merchandiser. A clear escalation path and SLA exist so problems do not hide between teams.

Next step

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