Most car rental offices run on Excel. Rentlenz is what comes after that.
Rentlenz started with a simple observation: car rental businesses were managing fleets, bookings, and customers through spreadsheets. This is the story of what I built to replace that.
Software engineers love to build complicated things. The best problems to solve are often embarrassingly simple.
When I started looking at how car rental offices actually manage their operations day-to-day, I expected to find some outdated legacy software, maybe a clunky desktop app from the early 2000s. What I found instead was a lot of spreadsheets.
The spreadsheet as a business system
Picture a car rental office managing 100+ vehicles across multiple locations. They need to know which cars are available, which are rented out, which are in maintenance, and which have upcoming bookings. They need customer records. They need to track transactions. They need their staff to be able to do their jobs without calling the manager for every question.
For many offices, all of this lives in Excel.
And to be fair — Excel works. Until it doesn't. Until someone overwrites a cell. Until two agents are updating the same file simultaneously and one version wins and the other is lost. Until the manager needs a real-time view of their fleet and instead has to ask someone to "update the sheet." Until the business grows and the spreadsheet becomes a fragile, unmaintainable source of partial truth.
The problem isn't that these businesses don't deserve better software. It's that the software that exists is either too expensive, too complex, or built for enterprise fleets that look nothing like a 100-car local operation.
What I built
Rentlenz is a back-office platform built specifically for car rental businesses at that scale — serious enough to need a real system, practical enough to not need a software consultant to operate it.
The platform is built around two roles, because that's how these businesses actually work:
Admin — full control over the operation. Admins can add and manage cars, register customers, onboard team members, and see analytics across the entire business: rental volume, revenue trends, fleet utilization, and more. This is the owner or manager's view.
Agent — the day-to-day operator. Agents can see the full car catalog and each vehicle's current status (available, rented, in maintenance), access the customer database, and handle the core transaction: creating a rental. Everything they need to do their job, nothing they don't need to touch.
The separation matters. When an agent can do their job confidently without admin-level access, you remove a whole class of mistakes. And when the admin can see everything in one place instead of across five spreadsheets, decisions get faster.
What the platform solves in practice
The Excel problem isn't just about data storage — it's about availability and trust. When your data lives in a spreadsheet:
- You can't know the real-time status of a car without asking someone
- You can't track a customer's rental history reliably
- You can't onboard a new agent and trust they won't break something
- You can't get any business insight without building a pivot table
Rentlenz replaces all of that with a single web platform. A car's status updates when a rental transaction is created. Customer records are tied to their rental history. New team members get an account with the right access level from day one. And the analytics are just there — no manual calculation required.
Where Rentlenz is going
The current platform solves the core problem: get car rental offices off spreadsheets and into a real system. But there's more on the roadmap that isn't shipped yet.
The next phase is customer-facing: a booking flow where customers can browse available vehicles, make reservations, and get confirmations — without calling the office. After that, there's a case for deeper fleet management: maintenance tracking, document expiry alerts for vehicle registrations and insurance, and multi-branch reporting.
The foundation is built for it. The features come when the business needs them.
The pattern I keep seeing
Dlvago and Rentlenz were built to solve the same category of problem from different angles. In both cases, the root issue was a manual process — copy-pasting into Excel, managing operations in a spreadsheet — that had become the default because no targeted software existed for that specific use case.
These gaps exist everywhere. The businesses inside them aren't waiting for enterprise software. They're waiting for something practical, affordable, and built for exactly what they do.
That's what I build.
Rentlenz is live. If you're running a car rental operation and want to see what it looks like — the platform is here.
Questions or thoughts? I'm always happy to talk through this stuff.
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