Custom extensions, API integrations, and seamless embedding into your system landscape.
Standard software often covers 90% – we close the last gap. We develop Modules, connect InvoiceNinja with your tools, and automate workflows.
From API integration to complete custom solutions – we cover the entire spectrum.
We make your systems talk to each other. Whether REST, GraphQL, or webhooks – we connect software with your CRM, ERP, or identity provider.
Often data formats from System A don't match System B. We develop middleware that sits in between, transforms data, and controls processes.
Want to use software features in your own intranet or customer portal? We embed software headlessly and build custom UIs around it.
Save manual work through intelligent automation. We develop bots and scripts that handle tasks automatically.
InvoiceNinja is powerful, but German requirements (ZUGFeRD, special layouts) are often tricky. We use the Laravel foundation for customizations beyond the UI.
We integrate invoicing completely invisibly into your app. Your system fires an API call, InvoiceNinja creates, sends, and reminds the invoice fully automatically.
Invoice paid? We use webhooks to unlock the service in your system, trigger shipping, or send a 'Thank You' SMS to the customer.
The standard editor has limits. We code PDF templates directly in HTML/CSS/Blade. Pixel-perfect implementation of your stationery, conditional texts (EU Reverse Charge), and dynamic QR codes.
How we implement InvoiceNinja development in practice.
The tax advisor needs data in a specific CSV/XML format that InvoiceNinja does not natively export.
An external script that pulls all new invoices monthly via API, maps account assignment information, and generates a DATEV-compliant export file.
Billing is based on usage, not fixed prices. Standard recurring invoices cannot handle this.
A cronjob service that aggregates usage data from your app at month-end and generates an invoice with dynamic line items in InvoiceNinja via API.
Customers should not be redirected to an external URL (invoice.domain.com) for invoices and payments.
Integration of the client portal via IFrame or API into your own login area. Seamless UX without media breaks.
Update-safe, scalable, and secure – why you should trust us with your development.
We don't modify the open-source software's source code. Instead, we use official APIs and plugin architectures. Your installation remains updatable and maintainable.
We understand not just the code, but the infrastructure beneath it. Our developers know how queries affect database performance and how to build scalable APIs.
We use modern, type-safe technologies: React, TypeScript, Node.js, Python, Go. Plus PostgreSQL, Redis, and Docker/Kubernetes for infrastructure.
Every line of code is written with security in mind. Input sanitization, secure authentication (OAuth2/OIDC), and compliance with data protection regulations are standard.
Our Tech Stack
From requirements to go-live – transparent and structured.
We review API documentation, analyze your requirements, and identify optimal integration points.
We design the solution: middleware, plugin, or script. Data flows, interfaces, and security concept are defined.
Agile implementation with code reviews, automated tests, and continuous coordination. You see progress in real-time.
Integration into your CI/CD pipeline or hosting on our infrastructure. Documentation and training included.
Let's get technical. We'll assess feasibility and effort.
Discover all InvoiceNinja services from WZ-IT.
Whether a specific IT challenge or just an idea – we look forward to the exchange. In a brief conversation, we'll evaluate together if and how your project fits with WZ-IT.
Trusted by leading companies
Timo Wevelsiep & Robin Zins
CEOs of WZ-IT
