API & System Integration
Make Your Systems Talk to Each Other
Every business runs on a handful of systems that refuse to share: the CRM does not know what accounting invoiced, the order system does not know what the warehouse shipped, and somebody retypes all of it - daily, with errors.
Green Line Solutions builds the connective tissue: custom APIs and reliable data synchronization that turn disconnected platforms into one coherent system with a single source of truth. It is some of the most valuable software a business can buy, because it pays for itself in hours nobody spends copying and pasting.
Systems We Connect
- ■ CRM platforms: HubSpot and others - deep, two-way syncs we have built and rebuilt for years, not just a Zapier recipe.
- ■ Accounting & billing: invoices, payments, and revenue data flowing automatically between operations and the ledger.
- ■ Order management & fulfillment: orders, inventory, and shipping status unified from storefront to warehouse.
- ■ Point-of-sale & retail systems: we integrate directly with POS databases to unlock customer, sales, and inventory data the vendor UI keeps buried.
- ■ Phone systems & VoIP: click-to-dial, screen pops, automatic call logging, and call analytics wired between your business phone system and your CRM.
- ■ Microsoft 365 & SharePoint: documents, lists, and identity connected to your line-of-business tools - see our SharePoint consulting.
- ■ E-commerce & payments: storefronts, Stripe, and payment workflows reconciled against real inventory and accounting.
Custom APIs, Done Right
When two systems have no bridge, we build one - and we build it like infrastructure, because that is what it becomes:
- ■ Documented and versioned: the next developer (yours or ours) can pick it up without archaeology.
- ■ Secured properly: scoped tokens, rate limiting, and audit logs on every endpoint.
- ■ Built for the real world: retries, idempotency, and queue-backed processing, so a network blip never becomes a duplicate invoice.
- ■ Monitored around the clock: when a sync fails, our systems alert us - not your month-end close.
Our Integration Playbook
Before any code, we chart where every field lives, which system owns it, and what "the same customer" means in each platform. Most integration failures are mapping failures - we prevent them on paper, where they are cheap.
Explore More Custom Development Services
Integration work sits at the center of our custom application development practice - and it usually unlocks the rest:
- ■ Custom Dashboards & Reporting - once systems are connected, report across all of them.
- ■ Business Process Automation - connected systems can hand work to each other automatically.
- ■ AI Development & Integration - give AI assistants live access to your business data.
- ■ Legacy Software Modernization - wrap aging systems in modern APIs instead of replacing them outright.