iPaaS platforms sell speed to first integration. Custom middleware sells control. The mistake is evaluating them on how fast the first flow ships, when the cost that actually bites is what happens at the fortieth change request.
Integration middleware is chosen badly more often than almost any other component of a commerce stack, and for an understandable reason: the evaluation measures the wrong thing. Everyone demos the first flow. Almost nobody models the fortieth change request.
Below is how we actually advise on this, including the cases where we recommend clients do not hire us to build something custom.
What you are really buying
An iPaaS is not primarily software. It is a maintained library of connectors, a hosted runtime, and — most valuably — somebody else’s responsibility when NetSuite changes an API. Custom middleware is the opposite trade: complete control of behaviour, complete ownership of consequences.
| Dimension | Celigo | Boomi | Custom |
|---|---|---|---|
| Time to first flow | Days — templated NetSuite/commerce flows | 1–2 weeks — visual build | 3–6 weeks |
| Prebuilt connectors | Purpose-built for NetSuite + commerce | Very broad, more general-purpose | None — you write them |
| Unusual business logic | Constrained by template shape | Flexible within the visual builder | Unconstrained |
| Cost shape | Subscription, grows with volume + endpoints | Subscription, grows with connections | High upfront, then hosting |
| Who fixes a breaking API change | Vendor | Vendor | You |
| Observability | Good out of the box | Good out of the box | Whatever you build |
| Skills required | Integration configuration | Integration configuration | Software engineering + on-call |
The cost curve nobody models
Subscription pricing looks expensive against a fixed build cost, and teams often reason that custom "pays for itself in year two". Sometimes it does. But the comparison usually omits the running cost of custom: on-call, dependency upgrades, the engineer who understands it leaving, and the week absorbed each time a platform ships a breaking change.
Conversely, iPaaS costs scale with exactly the thing you are trying to grow. Pricing tied to endpoints, flows or transaction volume means a successful year produces an invoice increase, and by year three the "cheap" option can be the expensive one.
When we recommend iPaaS
- Your flows are recognisable: orders down, fulfilments and tracking up, items and inventory across, customers synced. This is precisely what the templates exist for.
- You have no engineering team, or the one you have should be working on the storefront rather than on plumbing.
- You need it working this quarter. A templated flow genuinely can be live in days, and that is not marketing.
- Your ERP is NetSuite and your platform is mainstream. Connector maturity is highest exactly here — Celigo in particular is built around this pairing.
When we recommend custom
- Your business logic is the product. Complex allocation, bespoke pricing resolution, multi-warehouse rules that do not resemble anyone else’s — fighting a template here costs more than writing the thing.
- You are at a volume where transaction-based pricing has become the dominant line item.
- You need latency the platform cannot offer. Most iPaaS flows are scheduled or near-real-time; if you genuinely need sub-second, you need your own path.
- You already run engineering with on-call and deployment discipline. If that culture does not exist, custom middleware becomes an unmaintained liability within a year.
Questions to ask any vendor
Show me a failed flow
Not the happy path. What does the error look like, who is alerted, and how is it replayed after a fix?
How are changes promoted?
Is there a real dev-to-production path with version control, or does someone edit the live flow?
What happens at ten times this volume?
Ask for the pricing, not the reassurance.
What is not covered by the connector?
Every connector has gaps. A vendor who admits them readily is describing a product they know well.
Key takeaways
- Evaluate the fortieth change request, not the first flow — that is where the cost actually lands.
- iPaaS buys you someone else’s responsibility for API changes; custom buys you unconstrained logic. Both are real.
- Model three years including maintenance headcount; assume 15–20% of build cost annually for custom.
- Standard flows plus NetSuite plus a mainstream platform is the strongest case for iPaaS.
- A deliberate hybrid is fine. An accidental one is the worst of both.
360 Expert Solutions
E-commerce & ERP Integration Team
We build and scale B2B and DTC commerce on Shopify Plus, BigCommerce and WooCommerce, wired into NetSuite and Oracle. These articles are written by the engineers and architects who deliver those projects.
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