Connecting Island Solutions: When Excel, WhatsApp, and CRM Don't Talk to Each Other

Last week a client showed me his setup. Customer data in Excel, communication via WhatsApp, appointments in Google Calendar, invoices in sevDesk. Five tools. None of them connected.

He walked me through it the way someone does when they know things could be better but don't know where to start. And honestly: I see this exact setup in eight out of ten SMBs in the Eifel and Rhineland regions. It's not the exception. It's the default.

The thing is, none of these tools are bad. Excel is great for spreadsheets. WhatsApp is great for quick communication. sevDesk handles invoices reliably. Each tool works fine on its own. Just not together.

And that's where it gets expensive.

The Island Problem: Where Your Data Actually Lives

Think of your tools as islands. Each island has its own beach, its own language, its own rules. And in between? Water. No cable, no bridge, no ferry service. When data needs to get from one island to another, someone swims across. Manually. Copy and paste.

In practice, it looks like this:

• A customer calls. You enter their data in Excel
• Then you send them a WhatsApp message with a suggested appointment
• You add the appointment to Google Calendar
• After the appointment, you create the invoice in sevDesk. You look up the customer data in Excel again because sevDesk has no access to it
• The invoice goes out via email. Later you search Outlook for the correspondence because the customer has a question. The WhatsApp messages from back then are nowhere to be found because they're buried 200 messages deep

Sound exaggerated? It's not. I watched exactly this process at an electrician's shop with six employees. Three times a day. At Delivery Hero we had the same problem, just with 200 tools instead of 5. That's where I learned the solution isn't one mega-tool but connections between the existing tools.

What This Actually Costs

Let's do a conservative calculation. Just the manual data transfer, not the errors, not the lost messages, not the frustration:

• 5 minutes per customer interaction switching between tools
• At 15 customer interactions per day: 75 minutes
• Per week: over 6 hours
• Per month at 40 EUR employee cost: roughly 1,000 EUR

Then there are the errors. A wrong phone number, a forgotten appointment, an invoice with the wrong amount. In my article about the true cost of Excel I've done the detailed math. The hidden costs are often twice as high as the obvious ones.

Three Integration Tiers

There's no single solution for everyone. That's why I break integrations into three tiers. Depending on how many tools you want to connect and how complex your processes are, a different tier fits.

Tier 1: Quick Connections with Zapier or Make

Zapier and Make (formerly Integromat) are platforms that connect tools without requiring anyone to write code. They work on the principle: if X happens, then do Y.

A few examples I've set up for SMB clients:

• A new row is created in Google Sheets. Zapier automatically creates a contact in sevDesk
• Someone fills out the contact form on the website. Make sends a WhatsApp notification to the sales team and logs the lead in Google Sheets
• An appointment is created in Google Calendar. Zapier sends the customer an automatic reminder via email
• An invoice is marked as "paid" in sevDesk. Zapier updates the status in the customer spreadsheet

Setup takes between 30 minutes and 2 hours per connection. No developer needed. Zapier's interface is built so you can create connections yourself. Make is a bit more technical but more flexible.

The big advantage: you can start today. No project, no proposal, no waiting. Create an account, connect tools, done.

The downside: Zapier and Make work with simple rules. When your workflows have exceptions (and they always do), you'll eventually hit limits. On top of that, these tools depend on the APIs of the connected software. If sevDesk changes its API, the connection can break.

Typical costs: Zapier from 19 USD/month (Starter), Make from 9 EUR/month. With 3-5 active connections, you'll land at 50-100 EUR monthly.

Payback period: 1-2 months. Often even faster if you automate a particularly annoying manual task.

Tier 2: API Middleware for More Complex Workflows

When you're connecting more than 3-5 tools or your workflows need logic (if customer from region X, assign employee Y), Zapier won't cut it. Then you need an intermediate layer that I call API middleware.

In simple terms, it's a small program that sits between your tools and translates, filters, and routes the data. Like an interpreter who doesn't just speak the languages but also knows when to say what.

In concrete terms: instead of Zapier running a simple action on every trigger, middleware can merge data from multiple sources, apply rules, and send results to different destinations.

A real-world example: an installation company wanted new customer inquiries to automatically check whether the customer already exists (in lexoffice), whether an employee nearby is available (Google Calendar), and whether the required materials are in stock (their own Excel list). Only when all three conditions are verified should a quote be created and sent by email.

That's not possible with Zapier. With middleware, it is.

We use Node.js or Python for this, depending on the client's situation. The middleware runs on a server (usually in the cloud, often at Hetzner in Germany for data privacy reasons) and connects to the existing tools via APIs.

Typical costs: 500-2,000 EUR one-time setup, depending on complexity. Plus 100-300 EUR monthly for hosting, maintenance, and adjustments. At Plexito, this is included in the subscription model.

Payback period: 3-6 months. Worth it from the point where you spend more than 3 hours per week on manual data transfer.

Tier 3: Central Data Hub

The third tier is what I experienced at scale at Delivery Hero: a central system that serves as the single source of truth for all data. All other tools connect to it. The tools don't decide where data lives. The central system does.

In practice, this means: you have a CRM (or another central platform) where all customer data, orders, appointments, and communication come together. sevDesk pulls invoice data from there. Google Calendar gets appointments from there. WhatsApp messages are sent from there and replies flow back. Emails run through the system.

The advantage is clear: you have exactly one place where all information about a customer lives. No searching across five different apps. No "hang on, let me check my WhatsApp messages." Everything in one place.

This is exactly what large companies do, by the way. At New Relic, we used Salesforce as the central hub with over 50 other tools connected to it. At Delivery Hero, it was a custom system. The principle is the same, only the scale is different.

For an SMB with 5-20 employees, such a central hub can be built on HubSpot, Pipedrive, or a custom solution. Which system fits best depends on your processes.

Typical costs: From 2,000 EUR for initial setup. Ongoing from 249 EUR/month at Plexito (including maintenance, support, adjustments). A HubSpot setup can start cheaper but gets expensive fast as requirements grow.

Payback period: 6-12 months. Sounds long, but consider: this isn't just about saved hours. It's about better data quality, fewer errors, faster response times to customer inquiries, and an overview you'll never get with island solutions.

The Three Tiers Compared

Important: the tiers are not mutually exclusive. Many of my clients start with Tier 1, realize after a few months that they're hitting the limits, and then move to Tier 2 or 3. The Zapier connections they set up in the meantime were still worthwhile because they saved time immediately.

ROI: What Does an Integration Actually Deliver?

Numbers. I'm a numbers person. At DHL, Instacart, and Delivery Hero, every investment was evaluated by ROI. I do the same for SMB projects.

Let's take the electrician's shop from earlier. Six employees, 15 customer interactions per day, five isolated tools.

Tier 1: Zapier connects Google Sheets with sevDesk and Google Calendar

Time saved: roughly 3 hours per week. These are the simple, repetitive transfers that disappear immediately. Contact data flows automatically. Appointments sync.

Cost: 80 EUR/month (Zapier Pro).

Savings: 3 hours x 40 EUR = 120 EUR per week = roughly 480 EUR per month.

Net after tool costs: 400 EUR per month saved. In the black from month one.

Tier 2: Middleware for the quoting process

Additional time saved: roughly 4 hours per week. Creating quotes, checking availability, planning materials now run semi-automated. The employee only reviews and confirms instead of manually piecing everything together.

Cost: 1,500 EUR one-time + 200 EUR/month.

Savings: 4 hours x 40 EUR = 160 EUR per week = roughly 640 EUR per month.

One-time cost payback: after roughly 3.5 months. After that, net 440 EUR per month saved.

Tier 3: Central hub with CRM

Total time saved vs. the old setup: 8-10 hours per week. Nearly all manual transfers gone. On top of that come benefits that are harder to quantify: fewer errors, faster response to inquiries, better visibility for management.

Cost: 3,000 EUR one-time + 249 EUR/month (Plexito subscription).

Savings: conservatively 8 hours x 40 EUR = 320 EUR per week = roughly 1,280 EUR per month.

Payback: after roughly 3 months. After that, net savings of over 1,000 EUR per month. Plus the non-monetary benefits.

The math shows: even the most comprehensive integration tier pays for itself within a year. In most cases, much faster.

How to Find the Right Starting Point

I always recommend three steps to my clients before we talk about specific solutions.

Step 1: Count your tools. Write down which software and apps you and your employees use in daily operations. Not just the official ones. Also the private WhatsApp groups, the Excel file on the desktop, the notes app on the phone. Most business owners land at 7-12 tools when they're honest.

Step 2: Draw the connections. Take a piece of paper and draw arrows between the tools. Everywhere data is transferred manually. Each arrow is a potential automation. Count the arrows. If there are more than five, Tier 2 or 3 is probably the right choice.

Step 3: Measure the time. For one week. Every time someone manually transfers data from one tool to another, start a stopwatch. At the end of the week, you'll have a reliable number.

After that, you're in a good position to make an informed decision. Maybe two Zapier connections are enough and you're done. Maybe you need middleware. Maybe a central system. That depends on your situation.

What I Learned About Integrations at Delivery Hero

A brief detour, because I think the experience is relevant.

At Delivery Hero, we had a team dedicated exclusively to integrations. Dozens of developers whose sole job was connecting internal systems. Why? Because Delivery Hero grew through acquisitions. Every acquired company brought its own tools. The result: a patchwork of 200+ systems that somehow had to work together.

What I learned there:

1. Start small. The temptation to solve everything at once is strong. It never works. Take the one connection that hurts the most and automate that first
2. Data quality matters more than data volume. There's no point in connecting 10 systems if the data in the source spreadsheet is already wrong. Clean your core data before you automate
3. Every integration needs an owner. Not technical, organizational. Someone needs to regularly check whether the connection still works. With Zapier, that's a glance at the dashboard once a week
4. The best integration is one nobody notices. When employees no longer even realize that data flows between systems in the background, you've done everything right

These principles apply to a 200-person tech team just as much as to a 5-person trades business. The scale is different, but the underlying logic is the same.

What Happens Next

If you've read this far, you now know three things: your island solutions probably cost more than you think. There are three clearly tiered ways to solve the problem. And getting started is easier than most people assume.

My advice: start this week with Step 1. Count your tools. It takes ten minutes. If the number is above five, a conversation about which connections would have the biggest impact is worthwhile.

If you'd like, I'll take a look at your setup and tell you where I see the biggest lever. The initial consultation is free and takes about 30 minutes. Just drop me a message.