Jakob Papaj, Full-Stack Developer, AI Engineer & Technical Builder in Germany

Jakob Papaj / Germany

Most systems are invisible.

I build the instruments that show them.

Software. AI. Security. Hardware. Markets.

Eight languages. Fourteen systems in public. Six products live.

The code is never the hard part.

Deciding what the system should reveal is.

Jakob Papaj

Full-stack development, AI systems, cybersecurity, automation and high-end digital products.

See the work Start a project

Jakob Papaj / Germany

I build instruments for invisible systems.

Full-stack development, AI systems, cybersecurity, automation and high-end digital products.

See the work Start a project

01 — About

I build systems, products and digital experiences.

Full-stack development, AI systems, cybersecurity, automation and high-end digital products. Five years building, more than two hundred projects, and fourteen systems standing in public where anyone can read the code.

I work across the whole stack and below it. Frontend and backend, LLM applications and agents, defensive security tooling, embedded hardware, and the market systems I run for myself. Based in Germany.

More about how I work

VerifiedGitHub API

14public repositories→ 14languages shipped→ 13.0 Mbytes of code in public→ 6products live in production→

Counts read from the GitHub REST API for github.com/jakobxtb. Byte totals include vendored dependencies in forked work, which is called out where it applies.

02 — The instrument

This is the whole job.

Take something unreadable and make it legible. Hold the control.

14public repositories
14languages shipped
6products in production
6domains of practice

Press and hold. Let go and it falls back.

03 — Domains

Six domains. One way of working.

Cybersecurity & OSINT

    04 — Case studies

    Built. Shipped. In production.

    Six of fourteen, each with the problem, the system and a link to the code so you can check every word.

    01Systems

    JP Browser

    Native macOS application

    A macOS browser built on the real Chromium engine, with an AppKit shell and a translucent interface.

    Objective-C++Objective-CC++CMake
    Read the case study
    02Security

    JP God Eye

    Real-time intelligence console

    A live intelligence console for the planet, running entirely on free and open data.

    JavaScriptTypeScriptCesiumJSMapLibre GL
    Read the case study
    03Security

    AtlasVault

    Local-first encrypted desktop app

    An encrypted vault for secrets that never leaves the machine it runs on.

    RustTypeScriptTauriReact
    Read the case study
    04Security

    SentinelForge

    Defensive security platform

    Attack-surface discovery and security posture analysis, with the guard rails built in.

    PythonTypeScriptRESTJWT
    Read the case study
    05Markets

    Aurelius

    Quantitative risk and backtesting

    Portfolio risk analytics and strategy backtesting, open and inspectable.

    PythonFastAPINext.jsTypeScript
    Read the case study
    06Systems

    NexusTrace

    Distributed observability platform

    Tracing and service health for architectures where failure has nowhere obvious to point.

    Go 1.22TypeScriptNext.js 14PostgreSQL
    Read the case study

    All eighteen projects

    05 — Products

    Six things people can use today.

    Every one of these is live. Open them and judge for yourself.

    JP God Eye

    Intelligence console

    A 3D globe and a 2D intelligence board in one console. Live aircraft, ships, satellites, earthquakes, wildfires, traffic and public cameras, all on free and open data.

    €0 running cost16 open data sources19,400+ camerasMIT, self-hostable
    jpgodeye.notw.space

    JP Marketing

    Agency

    A web, SEO and AI agency built around one scrolling monitor metaphor. Four service tracks: SEO, web design, marketing and an AI assistant.

    SEOWeb designAI assistantGerman market
    jpmarketing.space

    Veltrix

    SaaS product

    A 24/7 AI receptionist that answers calls, qualifies leads, books appointments and follows up on missed calls. Self-serve setup, no onboarding call.

    €99 to €399 / monthSix industriesSelf-serve setupLead qualification
    veltrixbot.netlify.app

    Velore Studio

    Engineering studio

    A full-stack engineering studio positioned on performance: React and Vite frontends, cloud backends, and automated deployment pipelines.

    React + ViteFirestore / PostgreSQLCI/CDSeven cases
    veloredesign.netlify.app

    JP Holding

    Platform interface

    The interface and product design for a multi-asset investment platform: three mandate profiles, a risk questionnaire, a four-step onboarding flow and a brand collection.

    Onboarding flowRisk profilingMulti-asset UIBrand system
    jpholdingsgmbh.netlify.app

    The Vault

    Community product

    A crypto community and trading-systems product: member desk, position tracking interface and a tiered fee structure.

    Member deskPosition UICommunity tiersBrand
    jointhevault.netlify.app

    06 — System map

    The stack, weighted by what I actually ship.

    Node size is real: bytes of each language across every public repository, straight from the GitHub API. Hover any node.

    Languages

    • JavaScript8.77 M
    • TypeScript2.45 M
    • Objective-C++401 K
    • Python366 K
    • Swift192 K
    • Go54 K
    • Rust53 K
    • C++51 K

    Web

    • Reactfrontend
    • Next.jsapp framework
    • Tailwind CSSstyling
    • Node.jsruntime
    • Fastify / ExpressAPIs
    • PostgreSQL / Redisdata
    • Canvas / SVGrendering

    AI

    • LLM applicationsproducts
    • AI agentstool loops
    • Model provider APIsthirteen
    • RAGretrieval
    • Prompt engineeringpractice
    • Automationworkflows

    Security

    • OSINTinvestigation
    • Linuxenvironments
    • DNS / TLS / HTTPanalysis
    • Attack surfacediscovery
    • Endpoint securityhardening
    • SSRF defenceshipped

    Systems

    • Dockercontainers
    • CMake / Ninjanative builds
    • Tauridesktop
    • WebSocketrealtime
    • OpenTelemetrytracing
    • SQLitelocal-first

    Creative

    • 3D / WebGLexperiences
    • Three.jsscenes
    • CesiumJSglobe
    • MapLibre GLmaps
    • Motion designinteraction
    • Volumetric renderingthis site

    07 — Markets

    Markets are systems too.

    I trade Forex, crypto and digital assets, and I build the tooling around it: market analysis, risk models, automation and data pipelines. The same instinct as everything else here. Something is moving, and I want to see the shape of it.

    Aurelius is the public version of that thinking. Value at Risk, conditional VaR, Sharpe and Sortino, maximum drawdown, correlation matrices with eigenvalue decomposition, and an event-driven backtester that models commission and slippage instead of pretending they do not exist.

    Read this part carefully. This is personal practice and personal research. It is not advice, it is not a service, and no returns are claimed anywhere on this site. Aurelius does not predict markets. Trading carries real risk of loss.

    Read the risk engine
    • VaRhistorical and parametric
    • CVaRexpected shortfall
    • Drawdowndepth and duration
    • Correlationeigenvalue decomposition
    • HHIconcentration
    • Backtestcommission and slippage

    Build. Ship. Repeat.

    Jakob Papaj

    Start a project