Journalist and publisher

About

I'm Emin Mahrt, a product engineer and founder from Berlin, the publisher of proud magazine, and I'm building nuri.com. This site is where all of it gets written down properly, at a length that fits the subject.

Portrait of Emin Mahrt

Since 1999

German-Turkish IT guy since 1999, Berlin. I'm a product engineer and founder, shipping software since 1999. My work spans consumer apps, ad-tech, blockchain infrastructure and fintech.

In Berlin, I founded proud magazine, an independent socio-political publication recognized by the DFJV and archived in the German National Library. I co-founded abend.net, an ML-driven ad optimization platform, and abend.com, a Facebook Events discovery app, together serving thousands of paying clients monthly.

After passing the technical engineering interview from Facebook I decided to pass on that and became COO and CPO of the newly founded æternity Blockchain in 2017. I led product and operations, scaled the team to over 100 people, and contributed to Liechtenstein's Blockchain Act. In 2022 I served as Chief Product Officer at Börse Stuttgart Digital Exchange, leading product for one of Europe's first regulated crypto trading platforms.

I've been in Bitcoin since 2012: early mining, visiting Room 77, and contributing to different open source projects.

Now I'm building nuri.com. We acquired the Nuri brand after its insolvency, rebuilt the product from scratch, and launched the first and only passkey-derived and owned self-custodial Bitcoin wallet with non-custodial Visa card and integrated banking, live on iOS and Android across Europe, expanding to 100+ countries with a stablecoin Visa/Mastercard, onchain Euro IBAN and USD ACH account.

Journalist and publisher

The core rule of this site comes from proud magazine: free speech. Nothing here is censored.

Saying you do not care about privacy because you have "nothing to hide" is like saying you do not care about free speech because you have "nothing to say".

The details are on the principles page.

Contact

emin@emin.de · X · LinkedIn · Signal

What I work on

Wallets where the company holding the keys is not a dependency: passkeys carrying their own secret through the WebAuthn PRF extension, MuSig2 co-signing that decays to a single key on a Bitcoin timelock, and the recovery tooling that has to work when the provider is gone.

Alongside that, the agent side: x402 payments so software can pay for access without a signup flow, MCP servers so a model can call a system instead of scraping it, and the unglamorous work of making a website legible to both a search crawler and an agent.

What I write about here

How these articles get written

Long-form, one subject per piece, and only about things I actually built or measured. Every article opens with a TL;DR so you can leave early, carries a standalone takeaway per section, and ends with its real sources. If a number is in here, it came from a run I can point at.

Each article is also published as clean Markdown at its own URL, included in a public JSON API, and exposed through an MCP server. That is deliberate: the writing should be as easy for a model to quote correctly as it is for a person to read.

Who else writes here

Some short posts may come from the AI desk: an openly named AI writing desk, not a person. Its posts carry the AI-written badge on the page, in the Markdown mirror and in the structured data. It has no invented biography and no photo.

Elsewhere

Contact if you are working on something adjacent.