Custom Rompslomp integration development
Appfront builds custom Rompslomp integrations that fully automate your bookkeeping and invoicing, whether from your webshop, CRM, time tracking or your own application. Through the Rompslomp API, we automatically synchronise sales invoices, contacts, VAT entries and bank transactions. You save hours of manual data entry each month and keep accounts that are always current and accurate.
What is a Rompslomp integration?
Rompslomp is Dutch online accounting software made for freelancers and small business owners. The platform combines invoicing, bookkeeping, VAT return preparation and a bank integration in one simple environment, so business owners can keep their records without accounting knowledge. Sales invoices, contacts, expenses and bank transactions come together in an up-to-date overview of profit, loss and balance sheet.
In practice, a custom integration means: creating sales invoices programmatically based on orders from your webshop or billable hours from your time tracking; keeping contacts and customer details in sync; posting revenue and journal entries with the correct VAT rates and ledger accounts; and reading bank transactions to speed up reconciliation. This way, manual re-entry between systems disappears.
Appfront builds to the official Rompslomp API documentation and the OWASP ASVS security standard. We align the booking, VAT and error-handling logic with your actual bookkeeping, so the integration grows with your business and bookings keep running reliably even at peak volumes.
Book invoices automatically
Sales invoices are created in Rompslomp directly from your source system — with the correct customer, line items and VAT rates. No retyping, no forgotten invoices, and bookkeeping that is always up to date.
Insight into your figures
Because revenue, expenses and VAT are posted automatically to the correct general ledger accounts, your profit and loss statement and balance sheet stay current. You prepare your VAT return from data that does not first need to be corrected by hand.
Bank and receipts integrated
Bank transactions and uploaded receipts flow straight into your accounts, so reconciling and processing expenses goes faster. Fewer manual steps mean bookkeeping that is easier to maintain and gets finished sooner.
Our development process for Rompslomp integrations
We work to a proven methodology that removes uncertainty early and delivers a stable integration. From an initial analysis of your bookkeeping, invoice flows and source systems through to go-live and ongoing management, every step aims for an integration you can understand and trust.
We map out which bookings you want to automate, which data comes from which source system, which VAT rates and ledger accounts are involved, and how contacts and invoices should be linked.
We design the integration architecture, choose between API token or OAuth 2.0, and set up an error-handling and retry strategy for bookings.
Implementation with automated tests, structured logging and monitoring. You see working builds along the way.
Controlled go-live with data validation and a safety net, followed by ongoing management and further development.
What a Rompslomp integration delivers in practice
Every Rompslomp integration is tailored to your bookkeeping, invoice flows and adjacent systems. Below are the features we most often deliver for business owners who use Rompslomp as the foundation of their accounting.
API integration & authentication
A secure integration with the Rompslomp API using personal API tokens or OAuth 2.0, with the right scoped permissions. We set up token rotation, retry logic and monitoring so that your source system and Rompslomp keep communicating reliably.
Sales invoice synchronisation
Orders, subscriptions or billable hours from your source system are automatically created as sales invoices in Rompslomp — with invoice lines, VAT rates and the correct customer. Status changes flow neatly back to your own records.
Managing customers and contacts
Customer and contact details stay in sync between your webshop or CRM and Rompslomp. New customers are created automatically as contacts and changes carry over, so invoices always go to the right details without duplicate entry.
VAT and general ledger postings
Revenue and journal entries are posted with the correct VAT rates (standard, reduced, reverse charge or exempt) and general ledger accounts. This keeps your profit and loss statement accurate and your VAT return prepared from correct data.
Reading bank transactions
Bank transactions from the Rompslomp bank integration are read and matched against invoices, so reconciliation runs faster. We flag outstanding items and can pass payment statuses back to your own system.
Processing expenses and receipts
Purchase invoices and receipts from another system or your scanning app are booked as expenses in Rompslomp, including supplier and VAT. Less manual bookkeeping and an expenses overview that always matches your bank movements.
Typical use cases in practice
A Rompslomp integration looks very different from one business to the next. We see a number of recurring patterns, and for each we have a working setup that pays attention to invoicing, VAT and the right booking logic.
Sole traders and freelancers
Freelancers who send invoices, prepare VAT returns and connect their bank to Rompslomp. Billable hours or assignments from a time-tracking or project tool are automatically booked as sales invoices, so you spend less time on admin. See also our API integrations.
Small businesses
Small businesses, tradespeople, healthcare providers and service companies that run their full bookkeeping in Rompslomp. Revenue, expenses and receipts from your operational systems or scan app are booked with the correct VAT rates, so your profit and loss statement and VAT return stay up to date automatically. Also see our custom software development.
Webshops & e-commerce
Online sellers who want orders from their webshop booked automatically as revenue and sales invoices in Rompslomp, including customer details and VAT per order line. Your revenue administration keeps pace with every order. Read more about e-commerce development.
Start-ups & growing businesses
Start-ups who want their bookkeeping set up properly from day one, and growing businesses that want to connect their own application or platform to Rompslomp. We build a scalable middleware layer that grows with your volume of invoices and bookings.
Technology we use
We build Rompslomp integrations with the official Rompslomp API, combined with the backend stack that suits you. The precise choice depends on your source systems and booking logic, so that you or a future supplier can manage and further develop the integration.
Why choose Appfront for your Rompslomp integration?
Appfront has extensive experience building API integrations for a wide range of organisations in the Netherlands. We always start with a thorough analysis of your existing systems and processes. An integration should not only work technically, but also add practical value to the way you work.
For every integration, we write clear documentation and make sure your own team, or any future supplier, can understand and manage it. No black box, just transparent code and clear agreements on monitoring, alerting and maintenance.
You work with a dedicated point of contact who understands both the technical and the functional side. This keeps communication short, prevents misunderstandings and speeds up decisions when choices need to be made during development.
See also our wider services around API integrations, middleware, custom software and web app development. Do you work with other accounting software? We also build integrations with Moneybird, Jortt and InformerOnline.
- Experience with the Rompslomp API, invoices, contacts and bookings
- Specialists in accounting and invoicing integrations for freelancers and small SMEs
- Familiar with VAT logic, general ledger mapping and bank reconciliation
- Secure by default: token rotation, scoped OAuth permissions, secure vaults
- Structured error handling and retry mechanisms
- Comprehensive logging and monitoring from day one
- Clear documentation that you or your accountant can read and manage
- A fixed point of contact, no account managers passed around
- Ongoing maintenance and proactive further development
- A way of working tailored to your existing administration and systems
Security and privacy in Rompslomp integrations
An accounting integration always processes financial data and personal data of your customers and contacts: invoices, revenue, VAT and bank transactions. That is why Appfront builds to the OWASP ASVS security standard. This includes API tokens kept in secure vaults, scoped OAuth permissions, encryption in transit and regular audits of the booking and banking flows.
Because your administration is among the most sensitive data your business holds, we handle data minimisation and least privilege with care. We document the data flows and ledger mappings so that your record of processing activities is complete and you can demonstrate compliance with the GDPR. Audit logs make every booking traceable.
More on our security approach: information security policy and CVD policy.
- GDPR-compliant data processing and data minimisation
- Encryption in transit (TLS 1.2+) and at rest
- Role-based access and least-privilege principles
- Audit logs with traceable data flows
- Automatic retries and dead-letter queues
- Monitoring and alerting for anomalies
- Secrets management in line with best practice
- Documentation for your record of processing activities
Frequently asked questions about Rompslomp integrations
Answers to the questions we are asked most often about Rompslomp integrations.
A Rompslomp integration is a technical link between Rompslomp and another system, such as your webshop, CRM, time tracking or your own application. Through the Rompslomp API, invoices, contacts, VAT entries and bank transactions are read and written programmatically. This automates your bookkeeping without manual retyping. An integration can be simple (automatically creating sales invoices) or extensive (synchronising revenue entries, the general ledger and bank reconciliation across multiple source systems).
A Rompslomp integration suits freelancers, sole traders and small business owners who keep their bookkeeping in Rompslomp and want data from another system to flow in automatically. Think of a webshop that passes on revenue and invoices, or a time-tracking tool that sends billable hours to Rompslomp as invoices. If you work without repetitive data flows, an integration is often unnecessary; where manual retyping recurs, it saves time and reduces errors straight away.
A simple integration, for example synchronising sales invoices or contacts via the Rompslomp API, can go live within a few weeks. More extensive scenarios involving revenue entries, VAT logic, general ledger mapping and bank reconciliation across multiple source systems usually take longer. After an intake conversation, we give you a realistic estimate based on your administration and the systems to be connected.
We work with the official Rompslomp API alongside the backend stack that suits you: Node.js, Python, PHP, .NET or Go. Authentication runs through personal API tokens or OAuth 2.0. The API is in open beta and requires an active API add-on on your Rompslomp account. We build with structured error handling, retry mechanisms and monitoring, so bookings remain reliable even during peak volumes.
The cost is determined by the complexity of the data flows, the number of systems to be connected, the desired synchronisation frequency and the amount of custom work in the booking and VAT logic. Ongoing management, monitoring and support also affect the total investment. We always provide a clear quote following a no-obligation analysis of your situation.
Yes. An integration with your accounts processes financial and personal data, so Appfront builds to the OWASP ASVS security standard. We keep API tokens in secure vaults, work with scoped OAuth permissions, use encryption in transit and keep rights strictly separated per integration. We document the data flows so that your record of processing activities stays complete and you can demonstrate GDPR compliance.
Yes. Appfront regularly takes over existing integrations, even if they were originally set up by another party. We review the API integration, the booking and VAT logic, error handling and token rotation, document the current setup and propose improvements. From that point on, we handle adjustments, extensions and monitoring.
Rompslomp is aimed at freelancers, sole traders, start-ups and small business owners who want simple bookkeeping and invoicing. Typical users are service providers, tradespeople, care providers and webshop owners who send invoices, prepare VAT returns and connect their bank. An integration is especially valuable when you want revenue, hours or orders from another system to be booked into Rompslomp automatically.
Ready to build your Rompslomp integration?
Tell us which bookings or invoices you want to automate and which source system Rompslomp should connect to. We're happy to help with invoices, VAT logic, contacts and bank reconciliation. A no-obligation first call will quickly give you a clear picture of what's possible.