Quiet Signals
Lab

Alexander Hepburn
ML & Privacy Engineer
Netherlands

Privacy engineering for machine learning systems

Quiet Signals Lab is an independent ML practice building software and publishing applied research. The focus is on systems where privacy and auditability are properties of the architecture.

About

Thanks for visiting my website!


My name is Alex. I am an engineer and applied researcher working on privacy, safety, and reliability in ML and AI systems. Through my client and open-source work, I program systems that are often hybrid-—making the best of what probabilistic models offer, combined with deterministic constraints. My background in both ML and business lets me act as a bridge between the two, with end-to-end ownership of what I build.


I hold a master's degree in data science from the University of Amsterdam. My thesis was on Evaluating multi-task learning as an inductive bias for improving NLP robustness under distribution shift.


Don't hesitate to drop me a message if you are interested in what I do.

Software

Solander

Document Redaction Verifiable Evidence macOS Offline

A macOS app for redacting PDFs and scans, built around the part most redaction tools leave out: checking that the redaction held. Pages are rewritten rather than covered over, the output is reopened and re-read for anything still legible, and text the OCR could not resolve is reported rather than counted as clean. Every export can carry a signed record of what was removed, what was verified, and what was never examined. Runs without the network entitlement, so the operating system — not a promise — keeps documents on the machine.

Learn more → Pricing →
ShadowClip app icon

ShadowClip

Computer Vision Privacy macOS & iOS

A macOS and iOS utility for redacting sensitive content from screenshots before they reach AI tools, colleagues, or support tickets. All detection runs on-device — Apple Vision for faces and text layout, Natural Language for named entities, and hand-authored patterns for API keys and structured credentials — with no network entitlement and no data in transit.

Download on the App Store Learn more →
RAG Assistant for Zotero icon

RAG Assistant for Zotero

Knowledge Discovery Local AI Provenance ★  … Apache 2.0

A desktop application for semantic search over Zotero research libraries. Designed for researchers who need to navigate large literature collections and get answers with clear source attribution — not summaries that obscure where the information came from. Supports local LLMs end-to-end, so libraries containing preprints, embargoed work, or sensitive material never leave the user's machine.

macOS · Apple Silicon · Homebrew brew tap Quiet-Signals-Lab/rag-assistant-for-zotero brew install --cask rag-assistant-for-zotero
Learn more → View on GitHub →

Contractex

Python Library Information Retrieval Provenance PyPI ··· ↓ ··· Apache 2.0

ContractEx is a Python library for legal document intelligence. Every operation is a composable LegalTask that takes a LegalDoc and returns a LegalDoc, making it trivial to build privacy-respecting extraction pipelines, RAG chatbots, and document-automation workflows over contracts, statutes, regulations, identity documents, and more. Privacy controls are a mandatory first-class stage in every pipeline.

pip · Python 3.9+ pip install contractex
View on GitHub → View on PyPI →

Blog

Four controlled ablations that isolate when multi-task learning helps, when it hurts, and why — including the data-duplication control that separates task interaction from raw data volume.

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