Connecting the Unconnected: Building Custom Integrations for Your Legacy Systems

In today's hyper-connected world, the smooth flow of data between systems is the lifeblood of business operations. We have powerful SaaS platforms for CRM, marketing, and finance, all speaking the common language of REST APIs. But what about the systems that don't? What about the on-premise ERP, the homegrown database, or the critical legacy application that's been running your core business logic for decades?

These systems often hold your most valuable data, yet they exist in silos, disconnected from your modern toolset. Integrating with them is notoriously difficult, leading to manual data entry, brittle scripts, and stalled automation projects.

But it doesn't have to be this way. With the right approach, you can bridge the gap between old and new, and unlock the full potential of your entire tech stack. This is where a Business-as-Code philosophy transforms the challenge of system integration.

The Old Ways of Integrating with Proprietary Systems

Traditionally, developers faced a few unappealing options when tasked with connecting to a legacy or custom system:

1. DIY Point-to-Point Scripts: Writing custom code from scratch for every connection. This approach is quick to start but rapidly becomes a maintenance nightmare. The code is often brittle, lacks centralized security, requires deep system-specific knowledge for every developer, and doesn't scale.
2. Traditional iPaaS Platforms: While powerful for common applications, many UI-based iPaaS (Integration Platform as a Service) solutions stumble with proprietary systems. You might find there's no pre-built connector, and creating a new one is either impossible, prohibitively expensive, or a "black box" process outside your team's control.

These methods force you to choose between unmanageable code and an inflexible platform. Neither fits the modern developer workflow.

A New Paradigm: Integrations-as-Code

What if you could treat every integration—whether to Salesforce or your 20-year-old inventory system—as a simple, reusable service defined in code?

This is the core principle behind Integrations.do. We believe in Business-as-Code: defining, versioning, and managing all your integrations as code artifacts. This developer-centric approach gives you the power and flexibility to connect to any system, no matter how old or obscure.

As our FAQ states, "While we offer a library of pre-built integrations, you can easily define your own using simple configuration files." Let's break down how that actually works.

Building a Custom Integration: From Legacy to Library

With an agentic workflow platform like Integrations.do, you're not limited to a catalog. You're given the tools to build your own catalog. Here's how you can wrap a proprietary system and make it available as a simple function call.

Step 1: Define the Contract in a Configuration File

You start by defining the "shape" of the API, even if it's not a standard REST API. In a simple configuration file (e.g., YAML or JSON), you specify the endpoints, the HTTP methods (GET, POST, etc.), and the parameters it accepts. This file becomes the source of truth for how to interact with your legacy system.

Step 2: Abstract Away Authentication

Does your system use Basic Auth? A custom header with a static key? A quirky, multi-step token exchange? No problem. You configure the authentication method once within our secure environment. Our platform securely manages the credentials and handles the entire authentication flow for every subsequent call, so your developers never have to worry about it.

Step 3: Provision as a Reusable Service

Once your configuration is complete, Integrations.do provisions it as a new, fully functional service in your private library. Your complex, proprietary system is now an object you can access just like any other pre-built integration.

What was once a mess of custom clients and complex protocols becomes a clean, simple function call in your code:

import { Client } from '@do-sdk/client';

// Initialize the .do client
const doClient = new Client({ apiKey: 'YOUR_API_KEY' });

// Access your custom-defined legacy integration
async function getInventoryLevel(productId) {
  try {
    // 'legacyERP' is the custom integration you defined
    const product = await doClient.integrations.legacyERP.getProductById({
      id: productId
    });
    console.log('Stock Level:', product.stock);
    return product.stock;
  } catch (error) {
    console.error('Failed to query inventory:', error);
  }
}

// Run the workflow
getInventoryLevel('SKU-12345');

The developer using this function doesn't need to know if the backend is a SOAP service, a direct database query, or a screen-scraping script. The complexity is completely abstracted away.

The Benefits of a Code-First Approach

This method of building custom integrations delivers profound benefits that go far beyond just making a connection:

• Version Control: Your integration logic lives in Git. You can review changes via pull requests, track history, and revert if something goes wrong.
• Reusability: A single developer can define the integration once, and your entire team can reuse it as a simple function. This dramatically accelerates workflow automation.
• Scalability & Maintainability: When the legacy system's API changes, you update a single configuration file. You don't have to hunt down and refactor dozens of brittle scripts across multiple codebases.
• Enhanced Security: Credentials are not scattered in code or config files. They are managed centrally and injected securely at runtime.

Stop Working Around Your Systems. Start Working With Them.

Your legacy systems are not a liability; they're an untapped resource. By treating API integration as a first-class citizen of your development lifecycle, you can bring these powerful systems into the modern era.

The Business-as-Code philosophy empowers you to connect the unconnected, turning your most complex integration challenges into simple, manageable, and reusable services.

Ready to unlock the data in your proprietary systems? Discover how Integrations.do can transform your workflow automation today.