What Are System Integration Services? Types, Examples and Costs

Most companies do not have a missing-system problem. They have a four-systems-that-do-not-talk problem, and a person in the middle copying data between them. System integration services exist to remove that person from the loop.

This guide covers what those services actually include, the four integration patterns you will be quoted for, what each costs, real examples, and how to tell a capable provider from an expensive one.

What Are System Integration Services?

System integration services connect separate software systems — ERP, CRM, e-commerce, warehouse, accounting, HR — so they exchange data automatically instead of through manual re-entry. The work covers designing how the systems will talk, building and securing the connections, mapping data between formats that were never meant to match, and monitoring the result once it is live.

The deliverable is not a piece of software. It is a working data flow with an owner, an error path and an audit trail. A connection that moves data correctly on a good day but fails silently on a bad one is not an integration; it is a liability with a nicer diagram.

Why Systems Stay Disconnected

Three reasons account for most of it.

The systems were bought at different times, by different departments, for different reasons. Finance chose the accounting package, operations chose the warehouse system, marketing chose the CRM. Nobody was asked whether they would need to share data, because at the time they did not.

The older system has no usable API. Plenty of business-critical software still exposes nothing but a database, a file drop or a screen. This is the single biggest driver of integration cost, and the one most often discovered after the estimate.

Someone built a workaround that works. A nightly export, a shared spreadsheet, a macro. It functions, so it never becomes a priority — until the person who maintains it leaves, or the volume outgrows it.

The Four Types of System Integration

Point-to-point integration

Each system connects directly to each other system that needs its data. Fast to build for the first two or three connections, and the reason most integration projects eventually need rescuing: with n systems you can end up maintaining up to n(n-1)/2 connections, each with its own error handling and its own way of breaking.

Sometimes called vertical integration when each connection is built as its own functional silo. Sensible for a small, stable landscape. Expensive as soon as the landscape grows.

Hub-and-spoke (star integration)

Every system connects to a central hub rather than to each other. The hub handles routing and translation, so adding a system means adding one connection instead of many.

This removes the combinatorial problem but introduces a single point of failure, so the hub needs the availability budget of the most critical system it serves.

Enterprise Service Bus (ESB)

A shared messaging backbone that systems publish to and subscribe from, with transformation, routing and protocol mediation built into the bus. Sometimes called horizontal integration.

Strong fit for large landscapes with many producers and consumers of the same data. Heavy for anything smaller — an ESB for four systems is an architecture looking for a problem.

API-led integration and iPaaS

The current default. Systems expose well-defined APIs; an integration platform (iPaaS) or a purpose-built service orchestrates calls between them, often with pre-built connectors for common software.

Fastest route when your systems are modern and API-capable. The caveat is that connector coverage is what you are really buying — a platform with a connector for three of your four systems means the fourth is still a custom build.

A note on terminology: common data format, or a canonical data model, is not a fifth pattern. It is a design choice you can apply inside any of the four — defining one shared representation so each system only has to translate to and from that, instead of to and from every other system.

System Integration Examples

Real examples from software landscapes rather than textbook ones:

• E-commerce to ERP. Orders placed on the storefront create sales orders in the ERP, stock levels flow back to the storefront, and a failed payment does not create a phantom order. The hard part is not the happy path — it is reconciliation when the two systems disagree.
• CRM to accounting. A closed deal creates an invoice without anyone retyping it, and payment status appears back on the account record so sales stops chasing customers who already paid.
• Field operations to payroll. Hours captured on a mobile app flow into payroll with approval steps intact and an audit trail that survives a labour inspection.
• Legacy system to cloud application. An on-premise system with no API gets a purpose-built service in front of it that exposes the operations the new system needs, without touching the legacy code.
• AI over existing systems. Increasingly, integration means giving a model governed read and write access to business systems — through a defined tool interface with permission scoping and per-call audit logging, not a database password.

How Much Does System Integration Cost?

The variables that actually move the number, in order:

1. Whether the older system has an API. Wrapping a system that does not can double a timeline on its own.
2. How much the two data models disagree. Two systems with different ideas of what a "customer" is will cost more than two with different field names.
3. What happens when it fails. Fire-and-forget is cheap. Guaranteed delivery, retry logic, reconciliation and alerting is where the engineering hours go, and where skipping costs more later.
4. Volume and latency. A nightly batch and a real-time flow are different projects.

As shape rather than quotation: a straightforward integration between two modern, API-capable systems typically runs 4-8 weeks including testing. Add a legacy system without an API and 8-16 weeks is more realistic. iPaaS platforms are usually sold as a monthly subscription scaled to connection and volume tiers; a project-based integrator is usually quoted by the engagement or by the hour.

The cost people forget is the ongoing one. Integrations break when either side changes — an API version, a field, a business rule. Ask who owns that, and what the response time is, before you sign.

Types of System Integration Provider

Providers fall into four groups, and the right one depends less on size than on where your difficulty sits.

Global systems integrators. The large consultancies and IT services firms. Appropriate for enterprise-wide transformation programmes with many systems and many stakeholders. Priced accordingly, and usually structured so the people in the pitch are not the people on the project.

iPaaS vendors and their partners. Platform-first. Excellent when your systems are mainstream and well covered by existing connectors. Less good when a critical part of your landscape is custom or legacy.

Specialist software firms. Build the integration as software, including the parts no connector covers. The right fit when a legacy system, a custom application or an unusual data model is the hard part. This is where we sit.

Your own team. Frequently the correct answer for the second and third integration, once someone has established the patterns. Rarely the fastest answer for the first one.

How to Choose a Provider: Six Questions

1. What happens when the integration fails at 3am? The answer tells you whether they have run integrations in production or only built them.
2. Show me an integration you built against a system with no API. This separates connector configuration from engineering.
3. Who owns the data mapping decisions? Mapping is a business question wearing a technical costume. If the provider expects to decide alone, the result will encode their assumptions.
4. What does monitoring look like, and who watches it? An integration nobody watches is discovered broken by a customer.
5. What is the cost when the other side changes? Version upgrades and field changes are certainties, not risks.
6. What do we own at the end? Source code, documentation, credentials and the ability to run it without you.

Frequently Asked Questions

What are system integration services?

System integration services connect separate business systems so they share data automatically rather than through manual entry. The work includes designing the data flow, building and securing the connections, mapping data between formats, and monitoring the result in production. The deliverable is a working, owned and audited data flow, not a piece of software.

What are the four types of system integration?

Point-to-point, where systems connect directly to each other; hub-and-spoke, where all systems connect to a central hub that routes and translates; enterprise service bus, a shared messaging backbone for large landscapes; and API-led integration or iPaaS, where systems expose APIs that a platform orchestrates. A common data format is a design choice applied within any of these, not a separate type.

What is the difference between system integration and API integration?

API integration is one method of system integration — connecting systems through their application programming interfaces. System integration is the broader discipline, and includes cases where no API exists and the connection has to be made through files, databases or a purpose-built service in front of a legacy system.

How long does a system integration project take?

A straightforward integration between two modern, API-capable systems typically runs 4-8 weeks including testing. If one side is a legacy system without a usable API, 8-16 weeks is more realistic. The discovery step that determines which of those you are in is worth doing before the estimate rather than after.

Who are the biggest system integrators?

The largest global systems integrators are the major IT services and consulting firms — Accenture, Capgemini, CGI, HCLTech, Infosys, TCS and similar. They are built for enterprise-wide programmes. For a single integration, or where a legacy or custom system is the difficult part, a specialist software firm is usually a better match on both cost and depth.

Can you integrate a system that has no API?

Yes, and it is a common case. The usual approach is building a service that sits in front of the legacy system and exposes the operations the other side needs, reading and writing through whatever the system does support — a database, file exchange, or a scripted interface. It costs more than an API integration and it is the variable most likely to move a timeline.

Where to Start

Before approaching a provider, write down the specific flow you want to stop doing by hand, with a number attached: how many records a day, how many people touch it, how long it takes. That one sentence produces a far more accurate proposal than a description of the systems involved.

We build integrations as software, including the cases where one side is legacy, custom or missing an API. If you want a second opinion on a proposal you have received, or help scoping one, we are happy to look.

More on our approach: System Integration Services and Enterprise IT Integration.

Related reading: What Are IT Solutions? and AI Integration Services: How to Add AI to Your Existing Software.