Crosswind ApS · Denmark
Software built close to the problem it solves.
Aviation tools, self-hosted AI systems, e-commerce platforms and real-time graphics engines — built by an engineer who flies the aircraft the flight-planning software is for.
- Products shipped
- 2
- Consulting
- 8 years
- Deployment
- Self‑hosted
- Based in
- Denmark
Selected work
Products across aviation, AI infrastructure, games and commerce. Each one solves a problem that existing tools handled badly or not at all.
Fuel Planner
Aviation app
Cross-country fuel planning that answers the question EFBs can't.
Genus
Game
Puzzles you solve by reasoning, not by memorising — where the surface itself is the problem.
Crosswind AI
AI platform
Run your own models, on your own hardware, with no data leaving the building.
Warp Engine
Game engine
Drop-in 3D rendering for teams who need the pipeline open, not hidden.
Crosswind Webshop
E-commerce platform
A shop that stocks itself — new products arrive with copy in every language you sell in.
What Crosswind does
The same engineering applied to your problem — from domain modelling through to the infrastructure it runs on.
Aviation software
Flight planning, performance and operations tools built by someone who flies. Domain logic that survives contact with a real cockpit.
AI systems you own
Fine-tuned, domain-specialised models running on your hardware. Compiled, dependency-light, and no customer data leaving your building.
Web platforms
Elixir and Phoenix applications built to stay up — real-time interfaces, payments, i18n, and the infrastructure to run them.
Graphics and simulation
Vulkan rendering, engine work and interactive 3D, from the low-level pipeline up to the tools your team uses.
Consulting
Independent advisory work, separate from the products above — for the decisions where being wrong is expensive.
Technical due diligence
Code and architecture assessment ahead of an acquisition, an investment or a major build-vs-buy decision. What you are actually buying, what it will cost to keep running, and which risks are real.
- Codebase and architecture review
- Maintainability and key-person risk
- Security and compliance exposure
- Findings written for both engineers and the board
Independent investigation
An impartial technical assessment where the answer has consequences — a failure nobody can explain, a disputed delivery, a claim that needs testing against the evidence rather than against opinion.
- Root-cause analysis after an incident or failure
- Contract and delivery disputes
- Assessment of whether work meets its specification
- Conclusions stated plainly, with the reasoning shown
Security and standards
Gap assessment and audit preparation against the framework you actually have to satisfy, from someone who has built compliant systems rather than only reviewed them.
- Gap analysis and audit support
- Security architecture review
- Penetration testing
- Compliance processes built from scratch where none exist
Mathematics and computation
Problems where the hard part is the mathematics: optimisation, numerical methods, cryptography, or verifying that an algorithm does what it is claimed to do.
- Optimisation — linear and mixed-integer programming
- Numerical methods and high-performance computing
- Cryptography review — HMAC, AES, RSA, elliptic curves
- Algorithm correctness and complexity assessment
Standards worked with directly
- NIS2
- EU network and information security
- ISO 27001
- Information security management
- ISO 20022
- Financial messaging
- EU AI Act
- AI system compliance
- DO-178C
- Airborne software certification
- GDPR
- Data protection
- PSD2
- Payment services
- ETSI EN 303 645
- Consumer IoT security
Where the work has been
- Technical due diligence and code analysis for an international software-quality consultancy
- Payments infrastructure and cryptography in banking
- Safety-critical avionics software under DO-178C
- AI and security research at a Danish research institute
About Crosswind
Crosswind ApS is a Danish software company building tools where the domain knowledge matters as much as the code. The flight-planning software comes from actually flying cross-country; the AI platform comes from wanting models that run on hardware you control.
The work spans low-level graphics in C++ and Vulkan, machine learning in Rust without a Python runtime, cross-platform apps in Flutter, and real-time web platforms in Elixir and Phoenix — this site included.
Everything shown here is built and maintained in-house. Where a project is still in development, it says so.
Technologies in regular use
- Elixir
- Phoenix LiveView
- Rust
- C++17
- Vulkan
- Flutter / Dart
- Godot
- PostgreSQL
- Docker
- Terraform
- Ansible
- ggml
Who's behind it
Andreas Aabrandt Founder and Managing Director
Applied scientist and engineer, and the person behind everything shown here. Eight years as an independent consultant building systems across payments, gaming, research and aviation — with a research background in pure mathematics and high-performance computing behind it.
Education
-
PhD, arithmetic algebraic geometry
Technical University of Denmark 2017
-
Postdoc — high-performance computing (CUDA/GPU), computational number theory
University of Copenhagen 2017–2018
-
MSc in Engineering (Civilingeniør)
Technical University of Denmark 2012
Before Crosswind
- Four years on payments infrastructure and cryptography at Klarna, including incident command for major payment incidents and management of multiple teams.
- AAA game development in C++, plus experimentation frameworks and ML models for player behaviour.
- Compliance and machine learning for international banking, and AI/security research at a Danish research institute.
Licences
- Private Pilot License — Federal Aviation Administration 2025
- Private Pilot License — Swedish Transport Agency 2023
Have something to build?
Whether it's aviation software, an AI system you need to keep on your own hardware, or a platform that has to stay up — send a line describing the problem.
sales@xwind.org