Senior Backend Developer & Tech Lead: White-Label for Agencies & IT Partner for SMEs

Senior Backend & Tech Lead

Senior Backend Developer & Tech Lead

White-label capacity for IT agencies and a holistic IT partner for SMEs. ERP/CRM modernization, API integrations, and architecture guidance.

Milestone & Feedback-driven German & English Weekly review calls

For agencies: Backend capacity For companies: Modernize IT & processes

Industries & Business Domains

Medical Logistics

Custom ERP and logistics infrastructure for medical transport operations, focused on reducing manual coordination and automating shipment workflows.

Transport ERP Shipment Management Email Parsing Excel Reporting CSV Imports Live Collaboration

Enterprise ERP & Business Central

Full-lifecycle ERP modernization and custom development. Legacy Navision to modern Business Central upgrades and tailored integrations.

Business Central (BC 28) NAV 2009 to BC Upgrade AL Extension Dev C/AL to AL Migration Custom ERP Workflows

Funeral Services

Internal ERP systems for funeral homes with document automation, realtime collaboration and customer management tooling.

PDF Automation Realtime Chat Inventory Systems Google Calendar

Aviation & Surveillance

AVIATION

Realtime airport camera infrastructure with AI-assisted aircraft tracking and low-latency video streaming systems.

Camera Control AI Detection Live Streaming Realtime Processing

CRM & Lead Generation

SALES

CRM augmentation systems for customer acquisition, enrichment and automated validation workflows.

Lead Enrichment Google Maps APIs Twilio Validation Web Scraping

SaaS Infrastructure

PLATFORM

Large-scale admin platforms with authentication, collaboration tooling, permissions and remote infrastructure management.

AutoPlug Permissions Terminal Access SSL

Fintech & Payments

FINTECH

Payment infrastructure and unified APIs handling subscriptions, webhooks and transaction automation.

Stripe PayPal Webhooks Subscriptions

I would like to expressly thank you for your commitment. The software has decisively and sustainably simplified our daily work. We have become much more efficient and therefore more effective, thorough, transparent, and accurate. Thank you very, very much for that. - Dorina, Germany

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! - Jack, Australia

ABOUT ME

A senior developer, directly on your project

The work stays personal and straightforward. Questions are answered directly, decisions stay clear, and the project moves without unnecessary layers.

Book a meeting

Direct collaboration with a single developer

Direct contact

Communication stays direct, with clear answers and fewer handoffs along the way.

Thoughtful, accountable execution from a personal partner

Clear ownership

The work stays focused on the actual need, with steady attention and clear ownership throughout.

A steadier, more practical working rhythm

Practical delivery

Projects move with less friction, clearer decisions, and a more straightforward path from idea to launch.

Contact

Ways to work with me

Two clear models: white-label delivery for agencies, end-to-end modernization for companies.

White-Label

For Agencies

Backend capacity as your subcontracted senior developer and tech lead.

Flexible weekly capacity, hours or days
Java, Spring Boot, APIs and cloud
Silent delivery under your brand
Senior code reviews on request

Build & Run

For Companies

Modernize IT and processes end to end, from architecture to operation.

Legacy ERP/CRM modernization
API and third-party integration
Architecture and CTO consulting
Monthly cloud and maintenance flat rate

Book a free meeting osiris_support@pm.me

About Me

My name is A. Ruben Kandel, and I develop custom software solutions for businesses that need more than generic off-the-shelf tools. Since 2023, I have been working with clients internationally on ERP/CRM systems, business automation, backend infrastructure, and legacy modernization projects. My software development background started in 2019 through extensive open-source and independent work.

My primary focus is building scalable web platforms with complex business logic, from internal management systems and logistics software to SaaS infrastructure, API integrations, and workflow automation. I work closely with clients throughout development using a milestone- and feedback-driven process, allowing systems to evolve alongside real business requirements instead of rigid early specifications.

By handling architecture, development, deployment, and maintenance independently, I can provide direct communication, rapid iteration, and cost-efficient development without unnecessary overhead. For larger or ongoing projects, collaborative and team-based development can also be integrated when needed.

I work with clients across multiple industries including logistics, medical transport, fintech, lead generation, and operational management systems.

I communicate fluently in English, German, Portuguese, and Turkish, with basic proficiency in French.

Services & Process

What I focus on

Milestone- and feedback-driven, with a weekly review call as the product evolves.

Legacy Modernization & ERP/CRM

Replace aging systems safely, from NAV to Business Central, without disrupting operations.

API & Third-Party Integration

Connect Stripe, Twilio and ERPs into one workflow via REST APIs and webhooks.

Architecture & CTO Consulting

Code reviews, system design and reducing technical debt, with senior guidance.

Core stack Java Spring Boot REST APIs Webhooks SQL Docker Cloud Business Central (AL) Vue React

Frequently Asked Questions

Do you work white-label for agencies?

Yes. I work as a subcontracted senior backend developer & tech lead under your brand, on a flexible availability retainer (fixed hours or days per week).

How is pricing structured?

Agencies book a weekly retainer. Companies get a “Build & Run” model: a fixed price for architecture & development plus a monthly flat rate for cloud hosting & maintenance.

How does the process work?

Milestone- and feedback-driven: we hold weekly review calls so the software evolves with your real requirements instead of rigid early specifications.

Which languages do you speak?

I communicate fluently in German and English (plus Portuguese and Turkish).

Read the full contract FAQ →