Osiris-Team

A. Ruben Kandel — Custom Software Development & Consulting
Software Development • Consulting

Custom Software Development from A to Z

I deliver tailored, maintainable software — from mobile apps to web panels, with a focus on Custom ERP / CRM Web Panels. Weekly milestone reviews and rapid iterations keep you in control.

Milestone-driven 4.8/5 client avg. Java • Vaadin • Spring Docker • SQL • APIs
I speak/write English, Deutsch and know the basics in Português, Türkçe, Français.
Get a quote — contact

Services

Software development, code reviews, maintenance, integrations and consulting. I handle full project lifecycle or join teams as needed.

Custom ERP & CRM

Design and implement extensible admin panels with complex business logic, tailored to your workflows.

Legacy Modernization

Migrate, extend or wrap legacy systems while keeping data integrity and uptime at the forefront.

API & Integrations

Payment systems, Twilio, Google Maps, Dropbox, webhooks and 3rd-party platform integrations.

Cross-platform Apps

Native application development for Windows, MacOS, Linux, Android and iOS.

Performance & Security

SQL design, secure deployments, Docker, cloud-ready architecture and automated backups.

Mentorship & Reviews

Detailed code reviews, mentorship sessions and knowledge transfer to help your team succeed.

Selected Projects

A curated selection of recent professional and personal projects — open-source and proprietary.

Custom ERP for HELMSINGER Transport GmbH
Jun - Aug 2025 — Logistics platform, automated CSV imports, email parsing, Dropbox auth
Java · SQL · Spring Boot
Legacy CRM extension for bvm GmbH
Nov 2024 - Apr 2025 — External panel sharing DB, Twilio validation, Google Maps enrichment
Java · Twilio · Google Maps
Airport camera control
Jul - Oct 2024 — Enables live video streaming from multiple airport cameras, with full control over their feeds
Java · AI · Streaming
View more professional projects
1JPM
Maven/Gradle alternative — single-file Java project setup
HBrowser
Headless Java browser with cookie & file handling
jSQL-Gen
Compile-safe SQL generator for JDBC
View more personal projects

Packages & Rates

Transparent hourly packages — exact rates tailored per project. All offers include a detailed project overview and estimate.

Basic

20€ – 40€/h

Small fixes, bug-fixes, short tasks and consultations.

Pro

40€ – 80€/h

Medium projects, integrations and feature development.

Expert

80€ – 380€/h

Complex projects, architecture & audits, performance & security.

Client Feedback

“Really enjoyed working with him, put a lot of effort into the work and solved all my issues. Really recommend working with him and would love to work with him again in the future!” — l_12346, Australia
“Great communication and fast replies, delivered what was asked for. Before any important decision, always asked which approach was in my best interest.” — mani_monti, Portugal
More reviews on Fiverr.

Contact

Write a message — no login required. Typical response time: within a few business days.

Milestone + Feedback based Development

Unlike the traditional software development approach, where requirements are defined up front, and you only see the finished product months later, I follow a more flexible, collaborative process. We have a weekly call to review and test the software together, so you can give direct feedback as the product evolves. This way, you’re not locked into early assumptions; instead, the software grows with your needs and I get a deeper understanding of your vision. In fact, the projects where I’ve applied this method have consistently led to the highest client satisfaction and best results. The details of how often and long these meetings are, is fully up to you and the complexity of your project.

Frequently used Technologies

IDEs: IntelliJ IDE, CLion, Eclipse, Visual Studio Code, Visual Studio, Android Studio, Unity, Unreal Engine.

Software: Windows, Linux, Ubuntu, CentOS, Office (Word, Excel, PowerPoint etc.), git, GitHub, GitHub Workflow/Action, GitLab, Docker, JIRA, Slack, MySQL, MariaDB, PostgreSQL.

Libraries & Frameworks: Vaadin, Hilla, Spring-Boot, Tomcat, React, Angular, Bootstrap, Vue.js, Node.js, Electron, Java AWT/Swing/FX, REST APIs, Swagger/OpenAPI, Webhooks, HTTP, Android API, LibGDX, Maven, Gradle, Blender Plugin API, Wix API, Twilio API, Google Maps API.

Languages: Java: Cross-platform server, desktop, mobile, and web development. C/C++: Native application development. SQL: Database design, development, and management. JavaScript, HTML, CSS: Static and dynamic website development. Python: AI and LLM-driven applications. Electron, TypeScript, Vue, React: Cross-platform desktop and web app development.