API integration services for the systems you already use
Your shop, CRM, booking tool, payment provider and accounting each hold part of your data. I connect them through their APIs, so nobody has to copy data by hand. I work with companies that have no developer of their own, and with teams that want someone who has done these integrations before.
I'm all in on AI, so the work goes fast. I stay careful with anything that touches payments, customer data or orders.
I usually reply within one working day.
What I connect
Payment providers, CRMs, booking systems, ERPs, marketplaces and AI services.
Stripe and Paddle
Subscriptions, one-time payments, credits, invoices and webhooks. Paddle also handles VAT as the merchant of record. I have integrated both in live products.
CRMs like Salesforce
Leads, customers and inquiries synced in both directions. I fixed a two-way Salesforce sync for a real estate website.
Booking and scheduling systems
Appointments, staff logins with OAuth, classes and notes kept in sync. I added a second booking provider to a healthcare SaaS.
ERPs, warehouses and marketplaces
Stock, orders and listings moved between your systems and outside platforms. For a car marketplace I imported dealer stock and sent the listings to other marketplaces.
AI APIs
OpenAI, Anthropic, Google and xAI. I have used all four in live products.
Webhooks, logs and error handling
Every integration fails now and then. I add retries, readable logs and alerts, so a broken sync gets noticed before a customer complains.
How I work
You don't need to have everything figured out before we talk. An idea, access to the repo, a screen recording or a list of problems is enough. I look at what is there, tell you what I would do and what it costs, and then I build it.
I use Claude Code, Codex and my own agent workflows for reading code, planning changes, writing tests, refactoring and debugging. It is not vibe coding. It is senior engineering with a much faster loop.
AI-first, tested in the sandbox
Claude Code and Codex read API docs and write the repetitive client code quickly. I check every request against the provider's documentation and test it in their sandbox before it touches live data.
I stay in control
AI writes a lot of my code. I still make every technical decision, read every change before it ships, and test it. Fast, but meticulous: the speed is only worth something if what goes live is right.
The way you want to work
Some clients want to look at every change before it goes live, others want me to deploy. Some want a weekly call, most prefer written updates. I work well asynchronously, and I still ask the important questions when they come up.
I think like an owner
I still run my own online products. So when I build or fix yours, I think about traffic, conversion, revenue and support as much as about the code, and I tell you when something is not worth building.
Ways to work with me
Fixed price, a flat monthly rate, or hourly. It's always me doing the work, not an agency. If you're not sure, describe what you need and I'll suggest one.
Examples of my work
Integrations for clients and for my own products.
Two-way Salesforce sync
The sync for listings and inquiries was unreliable. I fixed it as part of a larger rescue and upgrade of the site.
A second booking provider
Onboarding, OAuth staff login, data sync, appointments, notes, classes and webhooks. I also moved the existing integration to a typed gateway while the product kept running.
Paddle billing and four AI providers
Subscriptions and credits with Laravel Spark and Paddle, Anthropic, OpenAI, Google and xAI in the agent workflows, and publishing to WordPress through its API.
What clients say
"He then built exactly what was needed and kept us informed throughout. Communication was clear and proactive at all times."
"Vincent works very well asynchronously: communication stays focused, there is little unnecessary back-and-forth, and he still raises the important questions when needed."
"Vincent was easy to work with and produced high-quality code. Would recommend."
Questions
Can you connect a system that has no good API?
Often, yes. Some tools offer webhooks, file exports or an older API. I check what is there and tell you what is possible.
Do you only work with Laravel?
Most of my integration work is in Laravel. If your app runs on Node.js, Python or Go, I work in that.
What happens when the other system changes its API?
The change shows up in the logs and alerts, and I update the integration.
Can you take over an integration someone else built?
Yes. I read the code, check the logs and fix what breaks most often first.
Do you test in the provider's sandbox first?
Yes. Stripe, Paddle and most other providers have a test mode. I build and test there before live payments or data are involved.
How do you charge?
Fixed price for a job with a clear outcome, a flat monthly rate for ongoing work, or hourly. Describe what you need and I'll suggest one.
Get a quote
Which systems you use, what should move between them, and what goes wrong today. A few sentences are enough. I'll reply with what I would do and what it would cost.
If you would rather talk first, book a 30-minute call or email contact@vincentschmalbach.com.