Data · Finance · Technology
Most of what's here started as something I couldn't settle by reading about it: how a cipher moves its bytes, how a sealed auction picks a winner, what an audit trail can actually prove. So each one is on the page as working code you can open.
No install, no sign-up, and most of it is open source.
Ciphertext
Key 2b7e151628aed2a6abf7158809cf4f3c
Choose a system, change an input, and follow it through. Each demo links to the repository it came from.
AES, written out by hand in plain JavaScript — every table, every round, no dependencies. I built it to see what actually happens between plaintext and ciphertext instead of trusting a black box, and kept the code readable so anyone else can follow along.
A working prototype of how modern blockchains settle: solvers compete for transactions in sealed-bid auctions and prove in zero knowledge that they played fair, with stake that gets slashed when they don’t.
However a decision was made — an ML model, a scorecard, a human rule — how do you prove later what it decided, why it was allowed, and that nobody rewrote the record? A small, dependency-free Python toolkit that checks every decision against a declarative policy, watches its inputs for drift, redacts the sensitive parts, and appends the outcome to a tamper-evident log.
Live boards for equities, ETFs, indices, FX, crypto, commodity futures and rate indices — several of them, each holding its own set. The browser talks only to this site’s API: provider access, identity resolution and credentials stay on the server.
There is always one more in progress.
Read how two of them workLonger pieces, kept here in full. Each one is the reasoning behind a project on this site.
Oct 7, 2025
9 min read
A credit application is refused, and six months later somebody asks why — that application, on that date, under the rules in force at the time. Most systems that decide at scale cannot answer, and the reason is duller than it sounds: nobody wrote the decision down in a form that stays honest.
Oct 25, 2024
12 min read
If you read “encrypted at rest” or “secure channel” in a spec, AES is usually the thing actually moving the bits. It hides under labels like disk encryption, token stores, TLS offload and “secure cookies”, quietly encrypting data even when you never call it directly.
I'm Mario. I work in structured finance and analytics in Italy. Code has run beside that for years — around a degree in finance first, then around the job — without ever being what I'm paid for. It kept going anyway.
I build a thing in order to understand it, and the part I keep coming back to is the moment it starts running on its own. The projects here are their own reason: some circle back to finance, the rest went where curiosity took them — cryptography, electronics, a few experiments with AI.
Work, ideas, or a question about any of this — the form lands straight in my inbox.