Your company probably already has too many systems and too little information. The CRM does not talk to the ERP, the e-commerce exports a spreadsheet to finance, and someone types the same order three times on three different screens. That is the classic symptom of data silos.
Each silo charges a silent price: manual rework, duplicated and conflicting information, and decisions made on data that was already outdated at birth. When the website stock does not match the ERP, the customer pays the bill -- and, right after, so does your reputation.
System integration exists to remove that friction. It makes your software exchange data automatically, instead of relying on manual exports and copy-paste. This guide explains, in decision-maker language, how it works -- API, webhooks, ERP, middleware -- and what to expect from a real integration project.
FWC Tecnologia has built custom apps and systems since 2020, and integration sits at the core of nearly every B2B project we deliver. We go from concept to cost, with concrete examples and the decisions that separate a robust integration from a hack that breaks at the first usage spike.
In This Article
- What system integration is and why it matters
- What a REST API is (explained to the decision-maker)
- Webhooks vs polling
- Integrating with ERP: Totvs, SAP and Protheus
- Middleware, iPaaS and data synchronization
- API security and authentication
- Risks, timelines and costs of an integration project
- How FWC runs integrations
- Frequently asked questions
- Need to integrate your systems?
What System Integration Is and Why It Matters
System integration is the set of techniques that makes two or more software applications exchange data and trigger actions on each other, without human intervention. In practice, it is what lets an order created in the e-commerce show up on its own in the ERP, generate the invoice and update stock.
The opposite is the data silo scenario: each system keeps its own version of the truth, and nobody knows which one is right. The result is the familiar "every report shows a different number", which erodes trust in your own operation.
There are three classic reasons to integrate. Ensuring data consistency (the same record across all systems), automating multistep processes (order, billing, logistics) and composing new services from existing systems -- like a WhatsApp chatbot that reads ERP stock in real time.
It is worth distinguishing the types of integration, because each has its own cost and complexity. The table below sums up the most common patterns in enterprise projects.
| Integration type | How it works | When to use |
|---|---|---|
| REST API (on demand) | One system requests data from another via HTTP | Real-time queries, fetching fresh data |
| Webhook (event-driven) | The system notifies another when something happens | Instant change notifications, no polling |
| Batch synchronization | Large volumes exchanged on a schedule | Nightly loads, ETL, reports, migrations |
| Middleware / iPaaS | A central layer orchestrates many connections | Many systems, transformation rules, scale |
| File exchange (legacy) | Import and export of CSV, XML, EDI | Old systems without APIs, external partners |
What a REST API Is (Explained to the Decision-Maker)
An API (application programming interface) is a contract: it defines how one system can request data or services from another. Think of it as a restaurant menu -- you do not enter the kitchen, you just order from what is listed, and the kitchen delivers.
Most modern APIs follow the REST style, which uses the web's own protocol (HTTP) to operate on "resources" like customers, orders or products. Each resource has an address (URL) and operations follow standard verbs: GET to read, POST to create, PUT to update, DELETE to remove.
The great value of REST is predictability. Since almost every serious system publishes a REST API -- from payment gateways to ERPs -- integrating becomes a matter of reading the documentation and honoring the contract, not reverse engineering.
A conceptual example makes it concrete. To fetch order number 1042, your app makes a simple call:
GET https://api.yourcompany.com/orders/1042
And the other system responds with that order's structured data, ready to use. No spreadsheet, no operator typing -- just two systems talking through the agreed contract.
Webhooks vs Polling: How Systems Notify Each Other
A REST API is great for asking, but it does not tell you when something changes. If you need to know the moment a payment is approved, you have two options: keep asking (polling) or ask to be notified (webhook).
Polling is your system asking "changed yet? changed yet?" every few seconds. It works, but wastes resources: most questions come back with nothing new. Zapier estimates that only about 1.5% of polling requests actually find an update.
A webhook flips the logic. Instead of asking, your system registers an address and the other system calls it as soon as the event happens -- payment approved, order shipped, document signed. It is the event-driven model, more efficient and closer to real time.
The practical rule of mature integrations combines both: the webhook notifies that something changed, and the REST API is called to confirm and fetch the full record. That way you get the speed of the event and the reliability of the query.
| Criterion | REST API (polling) | Webhook |
|---|---|---|
| Initiative | Your system asks | The other system notifies |
| Model | Pull (you pull the data) | Push (the data comes to you) |
| Latency | Depends on query frequency | Near real time |
| Resource cost | High (many empty calls) | Low (only on events) |
| Best for | Querying state on demand | Reacting to events instantly |
| Watch out for | Waste and delay | Needs public endpoint and redelivery |
Integrating with ERP: Totvs, SAP and Protheus
The ERP is usually the company's data heart -- finance, inventory, tax, purchasing. That is why the most valuable (and most delicate) integration almost always involves connecting your app or web system to the ERP already in production.
In Brazil, the landscape is dominated by Totvs, owner of Protheus, Datasul and the RM line. Protheus exposes REST APIs for its data models and uses token authentication; Totvs itself maintains an official API implementation guide in its technical center.
In the global enterprise world, SAP leads. It publishes hundreds of APIs on the SAP Business Accelerator Hub, most in the OData standard (a REST variant), with an environment to test and generate code before you even write the integration.
The real challenge of integrating an ERP is rarely technical -- it is business. Mapping that your app's "customer" is the ERP's "business partner", respecting tax rules and not overloading a critical system takes care. When the ERP is too old to expose an API, the conversation shifts to legacy system modernization.
Middleware, iPaaS and Data Synchronization
Connecting two systems is simple. Connecting eight -- each speaking a different dialect -- becomes an unmaintainable tangle if every connection is point to point. This is where middleware comes in.
Middleware is a software layer in the middle that receives, translates and routes data between systems. Instead of N direct connections, everyone talks to the middleware, which centralizes transformation rules, queues and retry attempts.
The cloud, managed version of this is iPaaS (integration platform as a service). Gartner defines it as a cloud service that lets you implement integrations between applications and data sources, internal and external, without managing the infrastructure.
It is not a niche: the global iPaaS market grew to US$ 8.5 billion in 2024, according to Gartner. Tools like MuleSoft, Boomi, Workato and Totvs iPaaS compete in this space, and make sense when there are many systems and high volume.
Whatever the tool, the end goal is data synchronization: ensuring a change made in one system propagates reliably to all others. Reliable synchronization is also the foundation for process automation (RPA), and choosing between real-time and batch sync is one of the first architecture decisions in any integration project.
API Security and Authentication
Opening an API is opening a door to your data. If that door has no lock, it becomes the weakest point of your operation -- and poorly protected integrations are among the leading causes of data breaches today.
The first pillar is authentication: proving who is calling the API. The market standard is OAuth 2.0, defined in the IETF's RFC 6749, which issues temporary access tokens instead of sending passwords on every call.
For simpler server-to-server integrations, API keys are used, but they require periodic rotation and must never be hardcoded in the code. Short-lived, minimal-scope tokens reduce the damage if a credential leaks.
The second pillar is protecting the door against abuse. Rate limiting blocks brute-force attacks and prevents a client from overloading the API; the OWASP API Security Top 10 lists broken authentication as one of the most critical API risks.
No integration is complete without treating personal data with the care the law demands. Encryption in transit, data minimization and access control are mandatory -- a topic we go deeper into in the guide on app security and data privacy.
Risks, Timelines and Costs of an Integration Project
Integration is the part of the project that founders most underestimate -- and the one that most blows the budget. The screen quickly disappears from the cost; the integration does not, because half the work is invisible: handling errors, reprocessing failures and dealing with the system on the other side.
Market numbers confirm the weight. According to Itransition, a single integration with a legacy system can cost from US$ 15,000 to US$ 100,000, and the integration share usually represents a relevant portion of an ERP project's total budget.
Three factors define the cost of integrating. The maturity of the API on the other side (documented and stable, or legacy and closed), the volume and frequency of the data, and the criticality (a financial integration demands far more testing than a simple record).
The biggest technical risk is fragile coupling: when the partner's system changes without notice and your integration breaks silently. That is why monitoring, logs and alerts are not a luxury -- they are what separates a professional integration from one that only finds the problem when the customer complains.
Since integration directly impacts the project's price, it deserves attention right at the quote stage. We break down that math in the guide on how much custom software costs, where integration appears as one of the main price factors.
How FWC Runs Integrations (B2B Cases)
At FWC, every integration starts with a map: which systems, which data, how often and who is the source of truth for each piece of information. Without that design, integration becomes a hack -- it works in the demo and breaks in production.
Solvace is a B2B service management platform, where data integration across modules and operational profiles is what sustains the operation. It is the kind of custom management system that only delivers value because data flows without rework.
3A Digitall is an electronic document management (EDM) solution. Projects like this live on integration: documents must come in, be indexed and stay available to other systems, with strict access control at every step.
Sudati App is a B2B industrial system connected to the factory-floor routine. Here, integrating means talking to the physical world and to corporate systems at the same time -- the classic case where integration, not the interface, defines the project.
Wehandle handles document checking in the field (field service), synchronizing data collected outside the office with central systems. It is the perfect example of resilient data synchronization: capture offline and reconcile when the connection returns.
The common thread across all four is the same: a well-built integration is invisible to the user and decisive for the business. When it works, nobody notices; when it fails, everything stops. That is why we treat integration as a first-class citizen, not an end-of-project detail.
Frequently Asked Questions
What is system integration?
System integration is the set of techniques that makes two or more software applications exchange data and trigger actions on each other automatically. It replaces manual exports and copy-paste with reliable, automated communication, eliminating data silos so the same information stays consistent across your CRM, ERP, e-commerce and every other system.
What is the difference between a REST API and a webhook?
A REST API works by pulling: your system asks for data when it needs it. A webhook works by pushing: the other system notifies yours the moment an event happens. Use REST to query state on demand and webhooks to react to events in real time; mature integrations combine both.
How do I integrate an app with an ERP like Totvs or SAP?
Modern ERPs expose REST or OData APIs with token authentication. Protheus (Totvs) and SAP both publish official developer documentation for this. The real work is mapping business concepts between systems, respecting tax rules and not overloading the ERP. When the ERP is too old for APIs, a middleware layer bridges the gap.
Is system integration secure?
It is when done right. Use OAuth 2.0 or rotated API keys for authentication, short-lived and minimal-scope tokens, rate limiting against abuse, and encryption in transit. Follow the OWASP API Security Top 10 and treat personal data under privacy law. Poorly protected integrations, not the concept itself, are what cause breaches.
How much does a system integration project cost?
It varies with the maturity of the API on the other side, the data volume and the criticality. A single legacy integration can range from US$ 15,000 to US$ 100,000, and integration is often one of the biggest cost drivers of an enterprise project. A simple, well-documented API is far cheaper.
What is middleware and when do I need one?
Middleware is a central layer that receives, translates and routes data between systems, replacing tangled point-to-point connections. Its managed cloud form is iPaaS. You need one when several systems must talk, when data needs transformation rules, or when volume and reliability demands outgrow a couple of direct connections.
Need to Integrate Your Systems?
If you made it this far, you probably already have systems that should talk and do not. The good news is that integration rarely requires throwing away what you have -- in most cases, it connects and amplifies what is already running.
FWC Tecnologia designs and builds integrations between apps, web systems and ERPs like Totvs, Protheus and SAP, always with security, monitoring and a clear data map. From the simplest webhook to the middleware that orchestrates dozens of systems.
Start by estimating your project with the price calculator and, when you want to design your integration architecture, request a personalized quote. We will map your systems and propose the safest, most economical path to eliminate data silos for good.