About DupScan

Who Built DupScan?

DupScan is built by Marcel Iseli, an indie macOS developer who creates native utility apps focused on performance, privacy, and simplicity. Marcel also builds MoniThor, a macOS menu bar system monitor.
DupScan

Marcel Iseli

Indie macOS Developer

LinkedIn

Why Does DupScan Exist?

DupScan exists because existing duplicate file finders on Mac are either subscription-based, bloated with unnecessary features, or abandoned and broken on current macOS versions. DupScan is a focused, native alternative that does one thing well.

Most duplicate file finders on the Mac App Store fall into two categories: all-in-one "cleaning" suites that bundle duplicate detection with cache cleaners, RAM optimizers, and other questionable tools — or free apps that haven't been updated in years and crash on modern macOS.

DupScan takes a different approach. It is a single-purpose app built with SwiftUI and optimized for Apple Silicon. It uses SHA256 hashing via Apple's CryptoKit framework for hardware-accelerated, cryptographically accurate duplicate detection. It makes no network calls, collects no data, and requires no account.

What Principles Guide DupScan?

DupScan is built on three principles: accuracy over speed (SHA256 hashing guarantees zero false positives), safety over convenience (Trash-based deletion with protected system paths), and privacy by design (zero data collection, zero network calls).

Accuracy

DupScan uses SHA256 cryptographic hashing to identify duplicates. Every file is compared by its actual content, not just its name or size. The two-pass optimization (4KB partial hash, then full-file hash) maintains this accuracy while keeping scans fast.

Safety

DupScan never permanently deletes files. Every deletion moves files to macOS Trash, where they remain until you explicitly empty it. System directories, user libraries, and app bundles are automatically protected and cannot be selected for deletion under any circumstance.

Privacy

DupScan contains no analytics frameworks, no tracking pixels, no crash reporters, and no telemetry of any kind. The app makes zero network connections. It operates entirely offline. Your files never leave your Mac.

What Other Products Does Marcel Build?

Marcel builds a portfolio of macOS and developer tools including MoniThor (system monitor), Mouzz (cursor highlighter), and Vibe Owl (security plugin). Each product reflects the same principles: native performance, privacy by design, and fair pricing.
  • MoniThor — A lightweight macOS menu bar system monitor that displays real-time CPU, RAM, GPU, battery, network, and disk metrics with live sparkline graphs.
  • Mouzz — A macOS cursor highlighter that makes your pointer visible during presentations, screen recordings, and tutorials with spotlight and click effects.
  • Vibe Owl — A security plugin that helps developers identify and fix vulnerabilities in their codebase.

All of Marcel's products share the same philosophy: solve one problem well, respect user privacy, and never charge a subscription for something that should be a one-time purchase.