End-to-end product development
Your MVP or SaaS product from a single source: data model, API, interface, payments, and deployment. I built my own product PEX exactly this way — subscription billing and iOS app included.
- MVP
- SaaS
- Stripe
- CI/CD
Freelance fullstack development
One developer. The whole system.
I build web applications end to end: Laravel and Symfony APIs, Vue and Nuxt frontends, Stripe billing, tests, and deployment — from one pair of hands.
- Available for long-term projects
- Remote, based near Stuttgart
- Apps used by 1,000+ employees
Services
What I build for you
Three ways I support teams and companies — from first concept to running product.
APIs & backends
Reliable REST APIs with Laravel or Symfony: authentication, roles, background jobs, WebSockets, and solid test coverage. Documented and ready to hand over.
- Laravel
- Symfony
- REST
- PHPUnit/Pest
Web frontends & mobile
Fast, accessible interfaces with Vue, Nuxt, or React — as a web app or in the App Store via Capacitor. TypeScript and end-to-end tests included.
- Vue/Nuxt
- React
- TypeScript
- Capacitor
Deadlines
Two deadlines on 31 Dec 2026
At the end of 2026, security support for PHP 8.2 ends, and so does the general transition period for paper and PDF invoices between German businesses. Both can be planned calmly.
PHP 8.2
31 Dec 2026
Last security updates for PHP 8.2
Until this date, the PHP project releases security updates for PHP 8.2; after it, none. Your application keeps running, but newly discovered vulnerabilities in PHP 8.2 will no longer be fixed.
See the upgrade checkE-invoicing (B2B, Germany)
31 Dec 2026
End of the general transition period
Until then, every business in Germany may still invoice domestic business customers on paper or, with the recipient's consent, e.g. as a PDF. From 1 January 2027, businesses with a previous-year total turnover above €800,000 must issue e-invoices; from 1 January 2028, all businesses. Exceptions include small businesses under § 19 UStG and invoices up to €250 gross; invoices to consumers are not affected. Since 1 January 2025, businesses have had to be able to receive e-invoices.
See the e-invoicing packageA short summary based on § 27(38) of the German VAT Act (UStG) and the Federal Ministry of Finance FAQ (as of March 2026) — not tax or legal advice. Your tax adviser can confirm what applies to your business.
Sources: php.net: Supported Versions § 27 UStG (German) BMF e-invoicing FAQ (German)
Packages
Fixed price instead of guesswork
Four clearly scoped packages for the most common requests. Everything beyond that I quote after a short call — from €85 per hour or €750 per day, plus VAT.
Upgrade check
€750
PHP 8.2: end of life 31 Dec 2026
One day of taking stock of your PHP/Laravel application before you invest in an upgrade: where does it stand, what is risky, and what does the path to supported versions cost?
- Inventory of PHP and Laravel versions and all dependencies
- composer audit for known vulnerabilities
- Assessment of the risks
- Written upgrade plan with a quote — fixed price or time and materials
Laravel upgrade & security audit
€1,900
The step after the upgrade check: your Laravel application brought to the current version and PHP 8.3 or newer, dependencies reviewed, OWASP basics checked, tests green. With a written report.
- Upgrade path and migration
- Dependency and configuration audit
- Report with prioritised findings
- CI pipeline for future updates
E-invoicing from custom PHP/Laravel B2B software
€2,400
B2B e-invoicing mandate: 2027/2028
Your custom B2B software invoices business customers? I add XRechnung and ZUGFeRD output from your existing invoice data, validated with the KoSIT validator — the way I built it for PEX.
- XRechnung 3.0 and ZUGFeRD 2.x (EN 16931 profile)
- Validation against the KoSIT validator
- Integration with your existing invoicing logic
- Test coverage, documentation and handover
Not tax or legal advice: which invoices you must issue electronically, and from when, is for your tax adviser to confirm.
Request e-invoicingTrades website in 10 working days
€2,900
A fast, GDPR-clean one-page website for trades and service businesses: services, process, contact, legal pages — on your domain and live within ten working days of receiving your complete content.
- Custom design in your colours
- Contact form with spam protection
- Cookie-free setup, consent only where needed
- Lighthouse 95+ on mobile
- Google Business Profile set up
All prices net, plus 19% VAT. 50% at project start, 50% on acceptance. Hosting, domains and licences are not included.
Projects
Selected work
Real systems in production — not tutorial projects.
PEX — Invoicing & Time-Tracking SaaS
2025 – todayInvoicing SaaS, built solo: e-invoicing (XRechnung, ZUGFeRD), DATEV export, dunning, customer portal and iOS app. Laravel 13 + Nuxt, version 1.0 live since 2026.
- Laravel 13
- Nuxt
- Stripe Connect
- XRechnung / ZUGFeRD
- DATEV
- Capacitor iOS
- Pest
- Playwright
Read the case study
Decoupled REST API with SPA frontend: race-condition-free conflict checking, approval workflows, iCalendar export, and 42 PHPUnit tests.
- Symfony 7
- Doctrine
- JWT
- Nuxt 4
- TypeScript
- Docker
- PHPUnit
Read the case study
Concept studies
Three landing pages, three industries
Fictional brands, built for real: what your website could look like. Each study is live to try, with a guide price for a comparable project.
Concept study
Döner Noir — a restaurant website
Website for a fictional Ocakbaşı restaurant in Stuttgart. Atmospheric images, a menu with a photo for every dish, opening hours and a table request — warm, dark and without third-party requests.
Comparable project: €2,900 – €4,500
About the project View the live demo (German)
Concept study
Wavelune — landing page for a music streaming service
Product landing page for a fictional streaming app. A moving opening, a waveform horizon, working app views, plan comparison and FAQ — dark, fast and without third-party requests.
Comparable project: €3,500 – €6,000
About the project View the live demo (German)
Concept study
Erlebnisburg Falkenwacht — a 3D fly-in for a theme park
Landing page for a fictional castle theme park. Scrolling flies you out of the clouds into the castle courtyard — built with three.js, plus height scales, a ticket calculator and directions.
Comparable project: €7,000 – €12,000
About the project View the live demo (German)
Guide prices, net, plus 19% VAT. You get a binding quote after a short call about scope and content.
Tech stack
One stack, every layer
From the interface down to the infrastructure — the tools I work with daily.
Frontend
- Vue.js
- Nuxt
- React
- Next.js
- TypeScript
- Tailwind CSS
Backend
- PHP
- Laravel
- Symfony
- MySQL
- SQLite
- Stripe
Infrastructure & quality
- Docker
- Nginx
- GitHub Actions
- Playwright
- PHPUnit & Pest
- Capacitor
Background
From banking to software development
A career with a detour — which is exactly why I understand processes, numbers, and users.
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since 2025
Freelance fullstack developer
Self-employed
My own SaaS product (PEX) and client projects — from the API to the iOS app.
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2022 – 2025
Software developer
Bechtle Managed Services GmbH
Fullstack development with Laravel and Vue.js: enterprise apps for training, travel requests, and inventory — used by over 1,000 employees. 2023: UI/UX design certification.
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2019 – 2022
IT specialist training (system integration)
Berufliches Schulzentrum Bietigheim-Bissingen
IT systems, networking — and the switch into development.
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2018 – 2019
Securities specialist
Wüstenrot Bank, Ludwigsburg
Order handling and client support in securities trading.
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2015 – 2018
Banking specialist training
Erich-Bracher-Schule, Pattonville
Focused on securities and accounting.
FAQ
Common questions
Which technologies do you work with?
Backend: PHP with Laravel or Symfony. Frontend: Vue.js, Nuxt, and React with TypeScript. Plus Stripe for payments, Docker and GitHub Actions for deployment, and Playwright and PHPUnit/Pest for testing.
Do you work remotely?
Yes, remote-first. For workshops or kickoffs I am also available on site in the Stuttgart/Ludwigsburg region of Germany.
Do you take over existing projects?
Yes. I join existing codebases, modernize legacy applications, and take on maintenance or feature work — starting with a short code audit as a shared baseline.
What does working together look like?
A free intro call, then a concrete estimate with effort and timeline. Development is iterative with regular demos. Handover includes documentation and tests.
What does it cost?
Ongoing support from €85 per hour or €750 per day, plus VAT. Clearly scoped work is offered at a fixed price — see packages. You receive a written quote after the intro call.
Who has to issue e-invoices from 2027?
From 1 January 2027, businesses in Germany whose total turnover in the previous year exceeded €800,000 must issue e-invoices for invoices to other domestic businesses (B2B). From 1 January 2028, this applies to all businesses. Exceptions include small businesses under § 19 UStG and invoices up to €250 gross; invoices to consumers (B2C) are not affected. Since 1 January 2025, businesses have had to be able to receive e-invoices. The basis is § 27(38) of the German VAT Act (UStG) and the Federal Ministry of Finance FAQ. This is a summary, not tax or legal advice — your tax adviser can confirm what applies to your business.
What happens when PHP 8.2 stops getting security updates?
After 31 December 2026, the PHP project no longer releases security updates for PHP 8.2. Your application keeps running, but newly discovered vulnerabilities in PHP 8.2 will not be fixed. Some Linux distributions keep their own PHP packages patched for longer — that depends on your hosting. Laravel 13 also requires at least PHP 8.3. The upgrade check shows how big the step is for your application.
What does the upgrade check cost?
€750 net plus 19% VAT, for one day of work. You get an inventory of the PHP and Laravel versions and dependencies, the results of composer audit, an assessment of the risks, and a written upgrade plan with a quote — fixed price or time and materials.
Are you available for long-term projects?
Yes. I support teams over months — embedded in your team or owning modules independently.
Contact
Let's talk about your project
Tell me briefly what you want to build — you'll get an honest assessment within 48 hours of whether and how I can help.
Or write directly to me@marten-ackermann.com