/\_/\ ( o.o ) > ^ < "In code we trust, in bugs we debug." /| |\ (_| |_) Senior Software Engineer @ Yubico | Open Source Maintainer | Certified Scrum Master Building secure systems, AI workflows, and the occasional decentralized dream
📍 Stockholm, Sweden | 🗣️ English, Swedish (native) | Spanish, Portuguese (elementary)
Full-stack dev (mostly backend) with 12 years building microservices, APIs, and fixing thread safety bugs. BSc in Computer Science from Stockholm University.
I like writing clean C#, test-driven development, and reducing technical debt. Currently working at the intersection of security, AI, and blockchain—turns out one rabbit hole wasn't enough.
Mission-driven projects that improve society + code that doesn't crash in production + learning new tech = what gets me up in the morning.
Expert (daily use, 5+ years): C#, .NET Core/.NET 5-10, Entity Framework Proficient: Python, TypeScript, JavaScript, SQL, REST APIs, gRPC, FIDO2/CTAP 2.2/2.3, CMake, Zig Familiar: Rust, C, OAuth, OIDC, GitHub Actions security hardening, Roslyn
Expert: Docker, Git, GitHub Actions Proficient: Kubernetes, Rancher, ArgoCD, Harbor, TeamCity, Octopus Deploy Familiar: Azure (Service Bus, EntraID, S3)
Expert: SQL Server, Elasticsearch Proficient: PostgreSQL, Kibana, Logstash Familiar: Redis
MCP (Model Context Protocol) and AI agent workflows • Claude Code and AI-assisted development • Bitcoin and decentralized exchanges • Hardware authentication protocols (CTAP 2.3, FIDO2) • Supply chain security and DevSecOps
Working on the Yubico.NET.SDK, a cross-platform SDK for YubiKey authentication targeting enterprise customers. Cryptographic signing, PKI, hardware security for .NET devs.
Day-to-day work:
- Authored 186+ PRs (66 in 2025 alone), reviewed 120+ PRs from contributors
- Shipped 6 SDK releases in 2025 (1.13.0, 1.13.1, 1.13.2, 1.14.0, 1.14.1, 1.15.0)
- Led CI/CD security hardening initiative (SHA-pinned 68 GitHub Actions)
- Mentoring on crypto correctness, backward compatibility, test quality
- Publishing signed libraries for Windows, macOS, Linux, Android
- Implementing FIDO2/CTAP 2.2 and CTAP 2.3 protocols in C# and C
- Filed and resolved 40+ issues (bug fixes, features, build stuff)
- Introduced Zig-based cross-compilation toolchain for Linux
- Performance improvements, logging, reducing tech debt
Notable work across 2024-2025:
PR #345 — CI/CD security hardening (Nov 2025)
Led comprehensive GitHub Actions security audit. SHA-pinned 68 actions across 12 workflows, eliminated credential leaks, added Dependabot for action updates, implemented security best practices throughout CI/CD pipeline.
Security leadership demonstrating deep understanding of supply chain attacks and DevSecOps.
PR #354 — CTAP 2.3 protocol support (Nov 2025)
Extended FIDO2 implementation to CTAP 2.3 spec. Added support for encrypted credential store state and forward-looking protocol features. Maintained backward compatibility with CTAP 2.2 and earlier.
PR #337 — Zig cross-compilation (Nov 2025)
Replaced GCC with Zig for Linux NativeShims compilation, targeting glibc 2.28 for broader compatibility. Unique build engineering approach enabling better cross-platform support without complex toolchain dependencies.
PR #328 — OTP serial number visibility (Oct-Dec 2025)
Implemented serial number visibility feature across 5 OTP configuration classes with comprehensive test coverage. Enhanced OTP configurability for enterprise customers.
PR #325 — Background thread crash safety (Oct 2024)
Fixed production crashes on macOS when people plugged in/removed YubiKeys. Turns out callbacks were firing on garbage-collected delegates. Implemented thread-safe disposal patterns across all platforms.
31 commits, 4,000+ tests, kept code coverage at 50%. Poll-based event detection on Linux, CFRunLoop timeouts on macOS, deterministic finalizer testing, resource leak detection via file descriptor monitoring.
PR #299 — CTAP 2.2 protocol implementation (Sep 2024)
First full CTAP 2.2 implementation with extension support, encrypted identifiers, FIDO2 capabilities for YubiKey firmware 5.4.3-5.8.3. Kept backward compatibility.
67 files modified, 40 commits, 3,964+ tests across Windows/Ubuntu/macOS. HKDF key derivation (RFC 5869), CBOR encoding, PIN/UV auth protocols, hmac-secret-mc extension.
CodeMapper (C#, Jan 2026)
Roslyn-based C# code structure analyzer that generates hierarchical maps optimized for AI/LLM agent context windows. Filters to public API surface (the Goldilocks zone for LLMs), extracts documentation, outputs line numbers for navigation.
Why it matters: AI agents need structured code understanding without bloating context. CodeMapper solves this with smart filtering and multiple output formats (text/JSON).
Features:
- Multi-project support with auto-detection
- Rich metadata (namespaces, base types, interfaces, attributes)
- Cross-platform install scripts (curl/wget for macOS/Linux, PowerShell for Windows)
- .NET 9 AOT-ready for fast startup
- Used in production for LLM-assisted code reviews
vslsp (TypeScript, Jan 2026)
LSP diagnostics tool for AI coding agents that interfaces with OmniSharp. Provides real-time C# compilation errors, warnings, and IntelliSense data to AI assistants through the Language Server Protocol.
Enables AI agents to understand type errors, missing references, and code issues before running builds—critical for autonomous coding workflows.
yubikit-mcp (Python, Oct 2025)
MCP server that lets AI assistants manage YubiKey operations. Instead of manual CLI commands, AI agents can discover devices, generate RSA keys on-hardware, configure touch policies, manage OATH/PIV/FIDO2 apps.
Built with FastMCP framework, translates JSON-RPC 2.0 MCP requests into ykman CLI operations. Supports Claude Code, VS Code, JetBrains IDEs.
fast-agent (Python, Mar 2025)
Framework for building AI agent workflows with full MCP support. Makes it easy to iterate on agent architectures without tons of boilerplate.
Features:
- 5 workflow patterns (Chain, Parallel, Evaluator-Optimizer, Router, Orchestrator)
- Interactive debugging
- Swap between Anthropic (Claude) and OpenAI (GPT-4o, o1/o3) via flags
- Config-driven MCP servers
- Multi-modal (images/PDFs)
wasm-game-of-life (Rust)
Conway's Game of Life in Rust compiled to WebAssembly. Sometimes you just need to watch patterns emerge at 60fps.
Personal blog and demo apps (Jekyll/HTML). Where I write about tech experiments and occasionally make things work in the browser.
Yubico.NET.SDK (C#)
Open source SDK with 117 stars, 59 forks. My day job, but also where I've contributed 186+ merged PRs and shipped 6 releases in 2025 alone. Enterprise authentication for .NET developers.
- Filed issues in Anthropic's claude-code and MCP python-sdk repos (protocol limitations, feature gaps)
- Active in discussions on MCP development
- Early adopter of Claude Code, Continue, and other agentic coding tools
- Built two production MCP servers (yubikit-mcp, fast-agent)
Blockchain infrastructure:
- bisq (Java) - Decentralized Bitcoin exchange, exploring P2P trading infrastructure
- Bitcoin Core - Following development
- Hyperliquid DEX SDK - Current DeFi stuff
Other interests:
- Bevy (Rust game engine)
- Anki (spaced repetition learning—yes I optimize how I learn)
- Open-WebUI, ChatterUI (LLM interfaces)
Sweden's public radio (think NPR meets Spotify's engineering culture). Started as a dev, became team lead/scrum master for a while, then senior dev. Managed editorial tools and infrastructure.
Senior developer (2022-2024):
- Built microservices pipeline from .NET 5 → .NET 8
- Deployed to Kubernetes (Rancher) via ArgoCD + Harbor
- Created health monitoring dashboard (Vue 3 + .NET)
- Modularized GitHub Actions for build processes
- Stack: Aurelia, TypeScript, Vue 3, .NET 8, Azure Service Bus, RabbitMQ, SQL Server, Elasticsearch, Kubernetes
Scrum master/team lead (2017-2022):
- Led team managing 30 legacy applications with different tech stacks
- Implemented CI/CD for all systems (TeamCity → Octopus Deploy → GitHub Actions)
- Set up monitoring, logging, health checks everywhere
- Ran agile ceremonies while shipping code
- Transformed legacy chaos into manageable systems
Full-stack developer (2014-2017):
- Built CMS from scratch (.NET Core, Knockout.js, Entity Framework, Elasticsearch)
- Architected logging solution (shared library + cluster provisioning)
- Migrated entire user base from legacy to new platform
- Interim Tech Lead for 5 months
- Zero-downtime migration for public-facing infrastructure
Founded and chair Sweden's largest flow arts community, a non-profit spreading poi, staff, and fire spinning. Turns out coordinating flaming objects and developers need similar risk management skills.
BSc Computer Science & Software Engineering Stockholm University (2011-2014)
- Certified Scrum Master (2016)
- Kubernetes App Developer (2023)
- Elasticsearch Core Developer & Operations (2017)
28 repositories | 52 starred repos | 186+ PRs merged in Yubico.NET.SDK | 120+ PR reviews | 40+ issues filed
Interested in companies pushing AI integration, blockchain infrastructure, and developer tooling.
Anthropic: Already engaged—filed issues in your repos, built two MCP servers, using Claude Code daily. Integrated Claude Code into Yubico.NET.SDK workflow with custom agent instructions (claude.yml). Built CodeMapper and vslsp specifically for AI agent workflows. I get MCP architecture (sampling, tools, resources) and bring security consciousness from hardware auth work and CI/CD security audits.
Block: Blockchain isn't just buzzwords for me. Forked Bisq, track Bitcoin Core, follow DEX infrastructure. Your mission around economic empowerment and open financial systems aligns with what I care about.
Similar companies: Already using AI agents for code reviews, docs, workflow automation. I understand what developers need because I am one.
What I'm looking for:
- Building dev tools that don't suck
- Making security accessible
- Open source communities solving real problems
- Mission-driven work
- Remote-friendly (occasional work from abroad would be nice)
What I bring:
- 12 years shipping systems that work
- Open source experience (186+ PRs authored, 120+ reviewed)
- Release management (shipped 6 SDK releases in 2025)
- Security leadership (led CI/CD security audit, SHA-pinned 68 GitHub Actions)
- AI tooling development (CodeMapper, vslsp, two MCP servers)
- Mentorship (code reviews on security, architecture, knowledge sharing)
- Cross-platform dev (Windows/macOS/Linux/Android)
- Build engineering (Zig cross-compilation, CMake, native library integration)
- Protocol implementation (FIDO2/CTAP 2.2/2.3, crypto signing, hardware tokens)
- AI-assisted development (Claude Code integration, automated code audits)
- Agile delivery (Scrum Master, led teams through migrations)
- Communication (technical writing, stakeholder management)
Reach out:
- Signal: @moonkin88.88
- LinkedIn: in/dennis-dyallo
- Linktree: linktr.ee/dyallo (all my links)
- Portfolio: dennisdyallo.github.io
- GitHub: You're already here
"Debugging is like being a detective in a crime movie where you're also the murderer." — Filipe Fortes I write tests so my future self doesn't hunt down my past self.