Services · Custom Software Development
Software for the work
your tools do not cover.
Internal tools, customer portals, integration layers and modernized legacy systems, built by one senior engineer in Next.js, TypeScript and Postgres. You talk to the person writing the code, and the code is in your repository from the first commit.
What I build
Internal tools
The operations tool your team currently runs out of a spreadsheet: forms, validation, roles, an audit log, and an export for the people who still want Excel.
Customer and partner portals
Logins per customer company, their own orders, documents and invoices from your ERP, and an assistant that answers only from their data.
Integration layers
The piece between systems that do not talk to each other, with idempotent writes, a replayable log and typed contracts, so you can always answer what ran and what it did.
Legacy modernization
Documenting what an old application actually does, pinning its behavior with tests, then replacing it module by module rather than in one risky rewrite.
Compliance layers
Structured e-invoicing from billing systems that cannot produce it, disclosure and logging for AI features, and the audit trails regulators and auditors ask for.
AI where it earns its place
Extraction, classification, drafting and search over your own data, added to the software where they remove work, not as a feature for the press release.
How a build runs
01
A scoping call, then a written scope
Thirty minutes to understand the process and the systems around it, then a short written scope with what is in, what is out, and a fixed quote.
02
A working slice in two weeks
The first usable piece reaches your team on real data early, because a demo on sample data hides the problems that matter.
03
Weekly increments
Every week ends with something your team can use and react to. Priorities move with what they learn, inside the agreed scope.
04
Handover without lock-in
Your repository, your accounts, documentation and a recorded walkthrough. Ongoing work continues on a retainer if you want it, and not if you do not.
Pricing
Custom software is quoted per scope after a free 30-minute call, not from a table, because the range runs from a small internal tool to the replacement of a core system. Contained builds such as an internal tool, a dashboard or an integration typically start around $3.5K. A new product follows the MVP Development ranges. Ongoing work after launch runs on a retainer quoted on the call.
What this looks like in practice
Worked examples of custom builds: the problem, the system, how it connects to what you already run, and where people stay in control.
An e-invoice layer that lets an old ERP issue XRechnung and ZUGFeRD before 2027
Reads invoice data from the ERP you already have, maps it to EN 16931, generates XRechnung or ZUGFeRD, validates every file with KoSIT and sends it by email or Peppol.
The existing ERP or billing system / KoSIT validator / Email (Outlook or plain SMTP) / Peppol access point / DATEV
Turning a 40-tab dispatch spreadsheet into an internal tool with rules, roles and history
Moves daily planning off a 40-tab spreadsheet into a web tool with validated forms, roles and a full edit history, while people keep Excel for analysis.
Excel and Google Sheets / Postgres / Microsoft 365 single sign-on / The ERP or TMS / Slack
A customer portal where B2B clients track orders, download documents and ask questions
Each customer company gets its own logins, live orders and shipments from the ERP and carriers, every document in one place, and an assistant that sees only their data.
NetSuite / SAP Business One / Carrier APIs or the TMS / Document storage (SharePoint or a DMS) / Outlook and Microsoft 365
Modernizing a 20-year-old Delphi or VB6 application with AI and tests, one module at a time
Documents what an old application really does, pins that behavior with tests built from real data, then replaces it module by module while it keeps running.
The legacy application (Delphi, VB6, Access, old PHP or .NET Framework) / SQL Server or Access database / Claude Code / The target stack / CI pipeline
Frequently asked questions
What counts as custom software here?
Software built around how your business actually works, usually because no product on the market fits: internal tools that replace spreadsheets, portals for your customers or partners, integration layers between systems you already run, and modernized versions of legacy applications. New products for founders are covered by MVP Development.
Should we buy a SaaS product instead?
Often, yes, and I will say so on the call. If a standard product covers the process with configuration, buying it is cheaper and faster than any build. Custom software earns its cost when the process is a genuine advantage, when it spans systems no product connects, or when the product you would buy forces the team to work around it.
Who owns the code?
You do, from the first commit. It lives in your repository, runs in your accounts, and the credentials are in your name. Handover includes documentation and a recorded walkthrough, so another engineer can pick it up. There is no lock-in and no proprietary framework underneath.
How long does an internal tool take to build?
A contained internal tool, such as one workflow with forms, roles, an audit log and an export, is typically a few weeks. A first working slice reaches your team within the first two weeks so they can use it on real data, and the rest is built in weekly increments against their feedback.
Can it work with the systems we already use?
That is usually the point. Most builds read from and write to an ERP, a CRM, an accounting system or a database you already run, through their APIs where they exist and through exports, database connections or supervised browser automation where they do not.
What does custom software development cost?
It is quoted per scope after a free 30-minute call, because custom software ranges from a small internal tool to a replacement for a core system. Contained builds such as an internal tool, a dashboard or an integration typically start around $3.5K. A new product follows the MVP Development ranges.