API Integration Services

Integrations that
don't break quietly.

Shopify to WMS. WMS to ERP. ERP to carriers. We build API integrations for 3PLs and fulfillment centers that handle real production volume — with error handling, retry logic, and monitoring built in from day one.

< 1 hr
critical response
1–2 wks
typical build time
Free
integration audit
Sound familiar?

How integrations actually fail

Orders disappeared between Shopify and your WMS.

Webhook fires. Shopify marks it sent. Your WMS never received it. No error. No alert. The order sat until a client emailed asking where their shipment was. This is what happens when an integration has no delivery confirmation, no retry queue, and no monitoring.

Every system shows a different inventory number.

Shopify says 200 units. Your WMS says 183. NetSuite says 211. None of them are wrong — they're just never in sync. Batch syncs that run every hour miss transactions in between. Conflict resolution was never designed in. Now you're manually reconciling three systems every morning.

It worked in testing. It breaks in production.

The API key expires after 90 days and no one rotates it. Rate limits kick in at peak volume and requests start dropping silently. A field that was always a string is suddenly an integer and the mapping throws an exception. Integrations that aren't built for edge cases accumulate failures over time — quietly.

What we build

Full-stack integration work

From a single broken webhook to a complete multi-system data architecture — we cover every layer.

eCommerce

eCommerce → WMS Integrations

Order ingestion, inventory sync, and shipment confirmation between your storefront and WMS. Built to handle order volume spikes, webhook failures, duplicate detection, and real-time inventory updates.

  • Shopify, WooCommerce, Amazon, eBay
  • Order create / update / cancel flows
  • Real-time inventory push
  • Shipment tracking callback
ERP ↔ WMS

ERP ↔ WMS Integration

Bidirectional sync between your WMS and ERP so inventory, orders, receipts, and billing stay consistent across systems. We handle field mapping, conflict resolution, and the edge cases that break most ERP syncs.

  • NetSuite, QuickBooks, Sage
  • Inventory & order sync
  • Receipt and PO matching
  • Billing data flow
Carriers

Carrier API Integrations

Rate shopping, label generation, tracking updates, and shipment event callbacks connected directly to your WMS or fulfillment workflow. Built for the carrier APIs as they actually work, not the documentation version.

  • UPS, FedEx, DHL, USPS
  • Rate shop + label generation
  • Tracking event webhooks
  • EasyPost / Shippo support
Webhooks

Webhook Architecture & Reliability

Most webhook implementations have no retry logic, no delivery confirmation, and no alerting. We build webhook infrastructure with queuing, idempotency keys, exponential backoff, and failure detection from day one.

  • Delivery confirmation + retries
  • Idempotency & deduplication
  • Failure alerting
  • Dead letter queue handling
Data

Data Mapping & Transformation

Systems rarely speak the same language. SKU formats, address structures, weight units, carrier codes — all need consistent transformation logic that handles missing fields, unexpected types, and format changes over time.

  • Field mapping & normalization
  • Format conversion logic
  • Missing / null field handling
  • Schema change resilience
Reliability

Error Handling & Retry Logic

An integration that fails silently is worse than no integration. We implement structured error handling, retry strategies with backoff, dead letter queues, and alerting so failures are visible and recoverable.

  • Structured error logging
  • Retry with exponential backoff
  • Rate limit handling
  • Partial failure recovery
Debugging

Integration Audits & Debugging

Inherited a broken integration or one that partially works? We audit the existing build, identify failure modes, and fix what's causing data loss — without rewriting everything unless that's actually necessary.

  • Failure mode analysis
  • Log review & root cause
  • Targeted fixes first
  • Rebuild only when needed
Monitoring

Monitoring & Alerting

After an integration goes live, the work isn't done. We set up monitoring for sync latency, error rates, and API health so you know about a failure before your clients do.

  • Sync health dashboards
  • Error rate alerts
  • API availability checks
  • Volume anomaly detection
Coverage

What we integrate

These are the systems we work in daily. Not documentation-level familiarity — actual production integration experience.

eCommerce → WMS
Systems
Shopify
WooCommerce
Amazon
eBay
TikTok Shop
BigCommerce
Use cases
Infoplus WMS
Extensiv 3PL WMS
Logiwa
ShipHero
Custom WMS
WMS ↔ ERP
Systems
NetSuite
QuickBooks
Sage Intacct
Microsoft Dynamics
Acumatica
Use cases
Inventory sync
Order records
PO & receipts
Billing & invoicing
WMS ↔ Carriers
Systems
UPS API
FedEx API
DHL API
USPS API
EasyPost
Shippo
Use cases
Rate shopping
Label generation
Tracking updates
Carrier selection rules
Custom & Internal
Systems
Internal databases
3rd-party tools
Reporting systems
Client portals
Use cases
Custom API builds
Middleware layers
Data pipelines
Legacy system bridges
Real results

What reliable
integrations actually change

These are outcomes from production integration work — not demo environments. Each one came from diagnosing what was actually breaking and fixing it at the root, not patching around it.

Review your integration setup
0
missing orders

After rebuilding a Shopify → WMS webhook flow with delivery confirmation and retry queue.

99.7%
inventory accuracy

After switching from hourly batch sync to event-driven real-time sync with conflict resolution.

6 hrs/day
manual work eliminated

Cross-system reconciliation removed after building a proper bidirectional ERP ↔ WMS sync.

< 2 min
order sync latency

Down from 3+ hour batch delays after migrating to event-driven order ingestion.

Our approach

Built for production,
not just demos.

01

Map the workflow before writing code

We document what data moves between which systems, in what sequence, and under what conditions. Every edge case — cancellations, partial shipments, returns, duplicate submissions — is accounted for before anything is built.

02

Design for failure, not just the happy path

We define how every error case is handled before writing a line of code. What happens when the API is down? When a rate limit hits? When a required field is missing? Reliability is architecture, not an afterthought.

03

Build, validate, then go live

Integration is built against test data, validated against real data in a staging environment, then launched to production in a controlled way — with rollback procedures and initial close monitoring.

04

Monitor and respond post-launch

We set up alerting and stay on through the first production cycle. If something surfaces in live conditions that wasn't in testing, we're on it — same day.

Why us

We've seen every way an integration can fail.

We've inherited broken Shopify webhooks with no retry logic, ERP syncs that only worked in UTC, carrier integrations built against test APIs that behaved differently in production. We debug these the same day.

Logistics-native, not just developer

We understand the warehouse and fulfillment workflows behind the API calls. An order isn't just a JSON payload — it's pick, pack, ship, bill. We build integrations that match how operations actually run.

We fix what's already broken

A large part of our work is inheriting integrations that partially work and finding what's failing. We've seen enough broken builds to diagnose fast — and we don't just patch symptoms.

Reliability is non-negotiable

We don't ship integrations that work in demo conditions. Every build includes error handling, retry logic, monitoring, and documentation. If something fails after launch, we're on it.

Direct access, fast response

No ticketing system, no first-response templates. When an integration breaks in production, you reach someone who knows the build and can respond under 1 hour on critical issues.

FAQ

Common questions

What systems do you integrate with?

Our primary focus is 3PL and warehouse tech stacks: Infoplus, Extensiv (3PL Central / Integration Manager), WooCommerce, Shopify, Amazon, NetSuite, QuickBooks, and major carrier APIs (UPS, FedEx, DHL, USPS, EasyPost). If it has an API, we can integrate it.

Can you fix an integration that was built by someone else?

Yes. We start with an audit — reviewing what was built, how it fails, and what the actual root causes are. Most of the time we can fix specific failure modes without a full rebuild. If a rebuild is the right answer, we'll tell you clearly and scope it.

How do you handle API rate limits and throttling?

Rate limit handling is part of how we build from day one: request queuing, exponential backoff on 429 responses, burst buffering, and alerting before limits become a problem. We also optimize API call patterns to reduce volume where possible.

Do you build real-time or batch integrations?

Depends on the use case. Order creation and inventory updates typically need real-time or near-real-time event-driven sync. Reporting and reconciliation tasks can be batch. We recommend the right architecture for each data flow, not a one-size-fits-all approach.

What happens if the integration breaks after go-live?

We set up monitoring and alerting as part of the build. For ongoing support clients, we respond to critical integration failures under 1 hour. For project-based work, we offer a post-launch support window and optional ongoing retainer.

How long does a typical integration take to build?

A straightforward eCommerce → WMS order sync takes 1–2 weeks from scoping to tested production launch. A full ERP ↔ WMS bidirectional sync with custom field mapping typically runs 3–6 weeks. We give fixed-scope estimates before work begins.

Get in touch

Let's talk about your Extensiv setup

Tell us what you're running and where the pain is. We'll respond within 30 minutes.

Response within 30 minutes
🔍Free integration audit included
💸No minimum invoices, no long-term commitment