Exact Online vs custom software: how do you choose?

What is Exact Online and what does it do?

Exact Online is the cloud package from the Delft-based software company Exact for the financial administration of Dutch SMEs. It is one of the most widely used accounting packages in the Netherlands and has grown from a pure general ledger package into a broader SME platform with modules for invoicing, inventory, project administration, payroll and CRM. For accountants, it is also a standard working environment via the accountancy portal.

In practice, the scope is broader than many people think: alongside finance, Exact Online also covers order-to-cash, purchase-to-pay, inventory, projects and, increasingly, analytics. At the same time, it is explicitly not a catch-all: for industry-specific processes or heavy logistics operations, the package is often used as a backbone with other systems alongside it.

So the crucial question is rarely "Exact or something else?" but rather "what do I do in Exact, what do I do outside it, and how do I connect those worlds?". Often the answer is a combination of Exact as the financial engine and custom software development for the part that makes the organisation distinctive.

The Exact portfolio: Online, Globe, Synergy

Much of the confusion starts with the product name. "Exact" is not a single product; it is a product line. There are three categories to know.

Exact Online

The cloud package for the broader Dutch SME market. Modular in design: Bookkeeping, Bookkeeping Plus, Trade, Manufacturing, Projects, Payroll, CRM. Subscription models vary by module and user type. Everything runs in the Exact cloud on EU infrastructure.

Exact Globe Next

The on-premise (or hosted) ERP package for the upper SME and mid-market. Functionally deeper than Exact Online, with more advanced manufacturing, multi-company structures and more complex inventory. It is often implemented by specialist partners. Migrating from Globe to Online is possible but is not a small undertaking.

Exact Synergy & accountancy portal

Synergy is the workflow, document and CRM layer that runs alongside Exact Globe (and, in a more limited form, alongside Online). In addition, there is the accountancy environment for firms: file management, compilation and review work programmes, and a publication layer on top of Exact Online.

All of them are aimed at broad applicability within Dutch administration. That is their greatest strength (Dutch tax rules built in, an established accountants' ecosystem) and their greatest limitation: as soon as an operational process structurally deviates, you end up either fighting the package or building a separate layer.

What exactly is custom software?

Custom software is not a "package we've adapted a bit". It is your own application, on its own codebase, with a data model derived from your process. You own the source code, you set the pace of further development, and the integration architecture is a design choice rather than a derivative of what the vendor offers.

In the Exact context, custom development often takes a different form to a replacement system. Many projects are a shell around Exact: a customer portal, an operational application, an AI layer or an industry-specific workflow that uses real-time data from Exact via the API. Exact remains the financial heart; custom development covers the processes the package does not support well. Sometimes the reverse is true: a fully custom platform with Exact used only as the bookkeeping end-point.

Custom development comes in several forms: a greenfield application, a layer on top of Exact via API integrations, a hybrid with multiple systems of which Exact is one, or a refactor of existing custom software that is connected to Exact. Which form fits depends on where the distinctive capability sits in your stack.

TCO and ownership: look beyond the licence

The biggest mistake in Exact-versus-custom decisions is looking at the licence instead of the total cost of ownership. Exact Online shows per-module and per-user prices that appear predictable. Custom development requires an upfront investment and looks expensive. In the short term that picture is accurate; over the timescale that matters for strategic decisions, it is not always so.

What is often underestimated in Exact TCO: licence escalation as users and modules grow, the cost of extensions from the App Center, implementation work for module extensions, partner work per release cycle, and workaround tools because a module doesn't cover one process well. The licence itself is often the smallest part as you scale.

What is often underestimated in custom-build TCO: active maintenance after go-live, security patches, infrastructure, and an ongoing development budget. If you commission custom software and let it become outdated, you will pay for it again.

A third route we often recommend is a hybrid, with Exact as the financial engine and custom development for the differentiating part. That keeps Exact TCO limited to what the package does well, and focuses your custom-build budget on what truly adds value. A good conversation about integrations and data flows is the first step.

The Exact Online API: what can it do and what can't it do?

The Exact Online API is one of the reasons the package has secured such a firm place in Dutch tech stacks. It is a REST API with OAuth2 authentication and a broad range of endpoints: general ledger, debtors, creditors, inventory, projects, payroll data, CRM. For anyone wanting to build around it, that is the starting point.

What the API does well

The API is functionally broad: almost everything shown in the Exact Online interface is available in some form via the API. Authentication via OAuth2 is standardised and the documentation is extensive. For standard integrations (webshop to Exact, CRM to Exact), ready-made connectors exist through partners or the App Center.

Where you hit walls

Rate limiting is a serious consideration: Exact enforces quotas per hour and per day, and at high volumes you will run into them. You need to design your integration architecture accordingly, with queueing, batch processing and smart polling strategies. The data models differ here and there from what you would expect from your own domain, so mapping work is part of any serious integration.

Webhooks, polling and sandboxes

Exact Online supports webhooks for a number of entities, which is useful for reacting to new invoices or mutations in real time. For entities without webhook support, polling remains the route. A good integration combines both, with idempotent processing on the other end. Test divisions let you validate an integration without touching a production ledger, which is essential on any serious project. On our page about smart API integrations, we describe the architectural choices we make there.

Hybrid architecture: Exact as the backbone, custom development on top

The most workable approach we see in practice isn't "choosing between Exact and custom software" but a combination. Exact does what it does well (bookkeeping, VAT, accounts receivable and payable, accountant integration), while custom software handles what the package doesn't do, or doesn't do well. Here are a few common patterns.

Client portal with live Exact data

Your own environment where clients can see outstanding invoices, track payment status, and review contracts and projects, with data retrieved in real time from Exact via the API. Branding and UX are fully in your hands, while Exact remains the financial source of truth.

Operational application with Exact as the accounting endpoint

Your own application that runs the operation (time recording, projects, inventory, planning) and sends bookings or invoices to Exact at the right moments. The operational process is designed around your work, and Exact receives the financial outcome.

AI layer and multi-tenant SaaS

For example, invoice recognition that reads supplier invoices, pre-books them and sends them to Exact as drafts, or a forecasting layer that uses booking data from Exact for cash flow predictions. In a SaaS context, this adds a per-customer integration with their own Exact environment: the custom platform is the product, and Exact is connected on the back end for each customer.

Dutch tax, VAT, ICP, Peppol and UBL 2.1

One of the biggest advantages of Exact Online is that Dutch tax requirements are built into its standard functionality. VAT returns, ICP declarations, annual report classification according to Dutch general ledger conventions, integration with the Tax Authorities for SBR reporting, and long-standing support for the Peppol network for electronic invoices based on the UBL standard.

Peppol and UBL 2.1

E-invoicing is gradually becoming a requirement across Europe for business-to-government flows and, increasingly, between businesses too. The Peppol network is the routing foundation, and UBL 2.1 (Universal Business Language) is the format. Exact Online supports sending and receiving via Peppol through its standard functionality. For custom systems, it is a design choice: you either connect to a Peppol Access Point directly, or route via an intermediary (such as Tradeshift, Storecove or a similar provider).

SBR and the Dutch Tax Authority

Standard Business Reporting (SBR) is the Dutch standard for periodic reporting to, among others, the Tax Authorities and Statistics Netherlands (CBS). Exact Online submits VAT and ICP returns through this channel; for custom systems, this requires an SBR integration, often via a specialist service provider.

What this means for your choice

If you only need Dutch tax handling and nothing special around invoicing, you do yourself a disservice by trying to reinvent this as custom software. It is work that Exact (and competitors like Twinfield and AFAS) simply built in. See also our parallel analysis on AFAS vs custom software for how the trade-off works out with a larger all-in-one suite. Custom pays off elsewhere — in operational processes, customer experience or industry-specific logic — and not in reprogramming VAT return mechanics.

GDPR, statutory retention, ePrivacy and eIDAS

Financial software almost always involves personal data: customers, suppliers, debtors, creditors, employees in payroll data. Four frameworks should be considered in any comparison.

GDPR and the data processing agreement

Exact acts as a processor for the data held in Exact Online. The DPA should tightly regulate this, including sub-processors and data locations (EU-only for Exact Online). With custom systems, you are either yourself responsible as controller, or you work with a hosting partner acting as (sub-)processor. In a hybrid setup you hold both roles at once, and that must be properly reflected legally.

Statutory retention obligation

The Tax Authority requires administrative records to be kept for seven years (ten years for administration related to real estate). With Exact, this is implicitly part of the package. With custom development, it is an explicit design requirement: append-only logs, immutable storage, and exportability in XAF/Auditfile format.

ePrivacy and eIDAS

A customer portal running alongside Exact touches ePrivacy rules (cookies, tracking, directed communications). For quotes and contracts, eIDAS, the EU regulation on electronic signatures, applies. Exact offers simple acceptance mechanisms; for qualified signatures you integrate with providers such as eHerkenning or a qualified trust service provider. In custom development, this is a design choice built into the application itself.

Integration freedom: how well does the system work with the rest?

Exact Online is deliberately open to integrations: the API is publicly available, and there is an extensive App Center with ready-made connectors for well-known webshops (Shopify, Magento, Lightspeed), CRM packages, payment platforms, time registration tools and industry applications. This is sufficient for most standard flows.

It gets difficult as soon as you want to integrate something atypical: a legacy industry application, your own data platform or an AI pipeline that takes data from Exact as input. There you need &of; a custom integration &of; an integration platform (iPaaS) to cover the translation and orchestration layer. Our page on integrations describes the architectural choices we make there — from direct point-to-point to event-driven with a messaging bus.

With custom software, integration starts as a design decision. If you treat the Exact integration as a first-class citizen from the outset (idempotent write operations, a retry strategy, monitoring), you get a more robust chain than an organisation that treats the integration as an afterthought.

Vendor lock-in: code ownership and exit routes

Lock-in is not a dirty word; it is a trade-off. Every package involves some degree of lock-in. The question is how deep it goes and what the exit route costs. There are three layers worth distinguishing.

• Data lock-in: Exact offers exports (XAF/Auditfile, CSV, API extracts). This is relatively well arranged, partly because the statutory retention obligation enforces it legally. Do test your export procedure properly before you sign, though.
• Process lock-in: the habits and workflows built around Exact. Accountants who work in Exact, staff who know the interface, partners who operate around Exact. This costs more to move than the licence itself.
• Integration lock-in: if you have built an ecosystem of integrations around Exact, replacing it becomes a bigger project than just migrating the accounting package.

Custom development shifts the lock-in: away from a vendor and towards your build partner and your own codebase. A serious build partner delivers the source code, a transparent deployment pipeline and documentation that another party can take over. That is the real exit route with custom work.

Sector choices: where does Exact fit, and where does it chafe?

The right choice varies considerably by sector. Here are a few typical patterns we come across.

Wholesale and e-commerce

For standard wholesalers with straightforward SKU structures and e-commerce integrations via Shopify, Magento or Lightspeed, Exact Online works well, often with the Trade module and an out-of-the-box connector. Custom software pays off once product configuration becomes more complex (variants, configurable products, quantity-based pricing) or when your own merchant portal needs to enrich the channel offering.

Construction, installation and field service

Project and work-order administration is a common place where Exact alone falls short. The Projects module covers the financial side well, but hours recording on site, material usage, photo reporting and planning at job level often run through custom apps that exchange data with Exact. A classic hybrid: an app for the shop floor, with Exact as the accounting end point.

Manufacturing and discrete production

For upper-end SMEs with serious production processes, Exact Globe Next is often the choice, sometimes supplemented with a MES system on the shop floor. For light production, the Exact Online Production module may suffice; for more complex operations, a MES or custom layer is added.

Start-ups and multi-tenant SaaS

For SaaS startups, Exact is rarely the core system (that's the custom product), but it is often the accounting system. The interesting integration questions concern revenue recognition, multi-currency, automated invoice flows from your own platform to Exact, and how to keep per-customer ledgers properly maintained.

When Exact Online is sufficient (without custom development)

Our pragmatic test: stay with Exact Online without custom development if you can agree with four of the statements below.

• Our processes are fairly standard for a Dutch SME: sending invoices, processing payments, filing VAT, running payroll, having the annual accounts compiled.
• Our stock, if we hold any, fits within what the Trade module can handle.
• Our e-commerce flows run through common platforms with existing connectors.
• Our industry-specific processes are limited or we cover them through App Center extensions.
• Our reporting needs fit within what Exact (or a light BI integration with Power BI) provides.

In that case you would be shortchanging yourself by spending budget on custom development where it isn't needed. Do make sure that exports into your own data platform are locked in from day one, that SSO via an identity provider is properly set up, and that the App Center extensions you depend on are stable to maintain.

When custom development pays off (alongside or instead of Exact)

Custom development pays off once an operational process structurally deviates from what Exact models, or once the customer experience is a distinctive element of the organisation. Patterns we see:

• Unique industry processes where standard modules fight against your daily work: timesheets with location and job context, maintenance planning based on your own logic, configurable production.
• Customer portal with live Exact data where branding and UX must be entirely in your own hands, but the financial source of truth remains in Exact.
• Integrations that don't go via the standard Exact API or App Center: legacy systems, industry-specific partners, own data platforms.
• AI layer on top of Exact: invoice recognition, cash flow forecasting, predictive collections or a custom RAG layer on top of your bookkeeping data.
• Multi-tenant SaaS startup where your product is the custom platform and Exact is only connected on the back end for each customer.
• Complex production processes where the shop-floor application or MES layer is a first-class citizen, and Exact (often Globe) handles the financial side.
• White-label customer portals running in parallel for multiple clients, with brand and data isolation that a packaged product rarely handles well.

Not every pattern means "replace Exact". In most of our projects Exact stays (or ends up) as the bookkeeping layer; the custom investment goes into the shell around it. That is what an introductory conversation about custom software maps out: which route for each layer of the stack.

The AI layer on top of Exact: new, fast-moving, loaded

A topic that comes up in every Exact conversation is the AI layer. Vendor-built AI often arrives in separate modules, built on an external model API. For general assistance that works well enough; less so once you want AI working on your specific data and want to keep control over governance, costs and quality.

The interesting AI applications we see landing on top of Exact:

• Invoice recognition and pre-booking: purchase invoices are read in, OCR-extracted, categorised (general ledger account, cost centre, VAT code) and sent to Exact as draft entries. A person checks and finalises the booking. See our page on automating invoice recognition.
• Cash flow forecasting: a custom model that combines bookkeeping data, debtor history and payment behaviour into a rolling cash flow forecast.
• Predictive collections: a likelihood of late payment per debtor, with a recommended action based on historical payment behaviour.
• Anomaly detection: ledger entries that deviate from the pattern, useful for internal controls.
• RAG over administrative documents: a chat layer that answers questions about contracts, quotes and invoices based on your own source data.

An AI layer that genuinely adds value requires its own architecture, its own data and its own governance. That is exactly where a custom layer on top becomes valuable: Exact as the source of truth, with an AI pipeline alongside it.

How to decide: a workable process

No flowchart can make this decision for you. What does work is a four-step process.

1. Write down the process, not the tool

Don't start with a vendor shortlist. Start with a document describing how your operation and customer experience work: what sits where, who sees which data, which laws and standards apply, which other systems are involved. That document is the touchstone against which you test every tool.

2. Carry out an honest fit analysis

Put that document alongside Exact Online (and possibly Exact Globe or similar packages such as AFAS and Twinfield). Don't ask "what does the website say?" but "what does the system do if we want this process in it?" — preferably with a proof of concept on real (test) data.

3. Make the custom question concrete

If Exact doesn't fit — or if you want a hybrid — describe what the custom layer should do, more specifically than "a system of our own". Which processes, which roles, which integrations, which compliance choices? The less vague, the better a build partner can estimate the work.

4. Plan for evolution, not an end state

Plan in phases: get a minimal viable version live in production first, gain experience, then build further. That applies to Exact implementations (don't switch everything over at once) and to custom projects (start with a core and expand based on what works).

Frequently Asked Questions

Can a custom application communicate fully with Exact Online?

Yes. The Exact Online API covers almost everything available in the UI. Points to watch are rate limits, OAuth token management, retry strategy, and correctly mapping Exact's data models onto your own domain.

What is the difference between Exact Online and Exact Globe?

Exact Online is the cloud package for the broad SME market. Exact Globe is the on-premise package for the upper SME and mid-market, with deeper functionality for production, multi-company structures and more complex inventory. Migrating from Globe to Online is possible, but it is not a small undertaking.

Do Peppol and UBL 2.1 work with Exact Online?

Yes, Exact Online supports sending and receiving via the Peppol network in accordance with UBL 2.1. For custom systems, you connect to a Peppol Access Point or via an intermediary; that is a design choice rather than a built-in feature.

Will we need to replace our accountant if we build a custom solution?

No. In almost all projects, Exact (or a comparable package) remains the final bookkeeping system, precisely because the accountant works in it. The custom layer focuses on operations or the customer experience.

How does Exact compare to AFAS?

Exact is strong in standard SME administration and has a broad accountancy ecosystem. AFAS positions itself as an all-in-one suite with deeper HR and payroll functionality integrated into the core system. See also our parallel analysis AFAS vs custom software.

What if we already have custom software and want to integrate it with Exact?

Start with an audit of the domains: which system leads for customer data, for product data, for financial transactions. Then design the integration as event-driven or API-pulled, with idempotent processing and monitoring. Our page on integrations describes that approach.

How much does a custom layer on top of Exact cost?

That depends on scope: how deep the integration goes, which processes are involved, what the compliance context is and which starting format you choose. A figure without context is misleading; a scoping conversation gives a more reliable picture. You'll find more background articles in our knowledge base.