Systems Integration
Connect the systems your organization already depends on.
Cass & York builds reliable integrations between CRM, ERP, accounting, payments, ecommerce, internal databases, customer applications, and third-party services.
We handle the business logic and operational controls that sit between the APIs.
The problem
Information moves between systems every day.
A customer enters information in one application. Someone copies it into another. A spreadsheet fills the gap. An employee checks whether the records match.
When something fails, nobody knows which system is correct.
We build integration layers that move data reliably and make those workflows easier to operate.
What we integrate
The systems behind the operation.
01
CRM
Salesforce, HubSpot, Zoho, GoHighLevel, and custom CRM systems.
- +Contacts
- +Accounts
- +Opportunities
- +Leads
- +Activities
- +Customer records
- +Lifecycle events
02
ERP & Accounting
- +Customers
- +Vendors
- +Orders
- +Invoices
- +Payments
- +Projects
- +Products
- +Inventory
- +Financial records
- +Operational transactions
03
Payments & Billing
- +Checkout
- +Subscriptions
- +Invoices
- +Payment status
- +Refunds
- +Customer billing
- +Payment reconciliation
- +Account provisioning
04
Ecommerce
- +Storefronts
- +Product systems
- +Inventory
- +CRM
- +Fulfillment
- +Payments
- +Customer records
- +Marketing platforms
05
Identity & Access
- +OAuth
- +SSO
- +External identity providers
- +User provisioning
- +Account synchronization
- +Role mapping
06
Data & Reporting Systems
- +Data warehouses
- +BI platforms
- +Reporting systems
- +Internal databases
- +Data feeds
- +File-based workflows
Reliability
The API call is the easy part.
Production integrations need operational behavior designed into them from the beginning.
- +Validation
- +Retries
- +Duplicate events
- +Failed records
- +Rate limits
- +Authentication
- +Partial updates
- +Conflicting data
- +Monitoring
- +Logging
- +Reconciliation
- +Source-of-truth decisions
- +Idempotency
- +Manual correction
We design those operational behaviors into the integration.
Selected work
Integration work in real operating environments
Vintel
Zoho CRM and Inventory integration.
A B2B platform connecting customer onboarding and account operations with Zoho CRM and Inventory. The system supported contacts, accounts, products, invoices, subscriptions, payments, sales orders, synchronization logs, webhook processing, and administrative tooling.
CRM integration · Inventory · Billing · Sync services · Webhooks · Monitoring
View Project →Shopify New York & Los Angeles
Enterprise application integrations.
Maintenance and extension of Shopify's New York and Los Angeles digital properties, including third-party integration work within established Next.js and Vercel applications.
Enterprise integrations · Production maintenance · Next.js · Vercel
View Project →Appreciation Financial
AI workflow connected to GoHighLevel.
An AI-powered financial intake workflow designed to collect structured client information and connect the resulting profile and appointment data to GoHighLevel.
CRM integration · Workflow automation · Structured data · AI agent
View Project →Integration patterns
The right delivery pattern for the workflow.
01
Real-Time APIs
For workflows that need immediate data exchange.
02
Webhooks & Events
For systems that need to react when something changes.
03
Scheduled Synchronization
For datasets that need periodic updates.
04
Batch & File Processing
For CSV, spreadsheet, SFTP, and high-volume import/export workflows.
05
Middleware
For workflows where a dedicated application should sit between multiple systems and own validation, business logic, and reconciliation.
How we work
Design the integration around ownership and failure.
01
Map the systems — identify what each system owns and how information moves today
02
Define the source of truth — decide which system controls each record and field
03
Design failure behavior — account for failed requests, conflicts, and incomplete data
04
Build and test — test normal, duplicate, delayed, and failed scenarios
05
Monitor — provide logs and operational controls for the integration
Start a conversation
Have two systems that should work together?
Tell us what needs to move, which platform should own the data, and what your team is doing manually today.
Discuss an Integration