You’ve shipped an API. You’ve also bought a seat on some integration platform. Both connect systems. Both move data. And at some point someone on your team — maybe you — said “wait, why do we have both of these?” and nobody gave a satisfying answer.
The reason the question lingers is that most explanations treat it as a vocabulary problem: here’s what an API is, here’s what iPaaS means, now go make better purchasing decisions. That misses the real question, which isn’t taxonomic. It’s about where integration logic lives, who owns it when it breaks, and what actually happens to both approaches once real production load arrives.
APIs and iPaaS are not competing answers to the same question — they sit at different layers of your stack, and the decision to use one, the other, or both depends entirely on which layer you’re trying to govern.
What an API actually gives you (and what it doesn’t)
An API is a contract. You publish a set of endpoints, you define the request and response shapes, you authenticate callers, and you let other systems talk to yours on those terms. The contract is yours to version, yours to deprecate, yours to monitor.
That’s genuinely powerful. When you own the API, you own the interface. You control how your system is consumed. Rate limits, authentication, schema evolution — all live in your house.
What an API does not give you is orchestration. An API tells callers what they can ask; it doesn’t coordinate the sequence of things that need to happen after they ask. If a new user signing up needs to provision a record in your billing system, enqueue a welcome email, sync to your CRM, and kick off a compliance check — that sequence, with its retries, error handling, and ordering guarantees, doesn’t live in any individual API. It lives somewhere in the middle.
The API defines the edges of your system. Everything between those edges — the routing, the transformation, the retry logic, the sequencing — has to live somewhere else.
Where it actually lives in most mid-market stacks: a mix of Lambda functions, cron jobs, webhook handlers in your application code, and some integration tooling that nobody fully owns. The API contract is clean. The space behind it is archaeology.
An API is a clean contract at the boundary of a system; it cannot govern what happens when multiple systems need to cooperate.
What iPaaS actually gives you (and where it gets uncomfortable)
An iPaaS — an Integration Platform as a Service — is the place where cross-system orchestration lives. It’s the answer to “who coordinates the sequence?” It holds the workflow logic that says: when event A arrives from system 1, transform it, call system 2, wait for confirmation, call system 3, and if any step fails, retry it twice before routing to a dead-letter queue.
Done well, this is a significant operational win. You get a single place where integration logic is visible, testable, and (with better platforms) versioned. You remove the class of problems that come from integration logic scattered across application code, Lambda scripts, and tribal knowledge.
Where iPaaS gets uncomfortable is in three predictable places.
First, pricing. A large class of integration platforms charge per execution — per task, per recipe run, per action step. That model seems fine when you’re handling thousands of events a month. It gets uncomfortable the first time a customer floods your webhook, a loop runs more iterations than expected, or you promote a workflow to production and traffic scales by 10x. The bill moves when your traffic moves, which means your integration costs are unpredictable at exactly the moment they matter most.
Second, observability. Many platforms log execution state inside their own UI, behind their own query interface. When something goes wrong at 2 AM, your SRE team can’t pull a span into your existing observability stack — they have to context-switch into the integration vendor’s console, with whatever visibility that vendor decided to give you. That’s a structural blind spot that application monitoring can’t compensate for.
Third, version control. The integration logic that now runs your onboarding, your billing events, and your AI pipelines is production software. It should be treated like production software — reviewed, versioned, rollable-back. Most platforms store workflows in their own database rather than your Git repo. That means changes don’t go through your engineering workflow. They don’t show up in your diff history. And when something breaks, reconstructing what changed and when is its own investigation.
iPaaS solves the orchestration gap that APIs leave open, but not all platforms give you the ownership properties you’d demand from any other production system.
The question that actually matters: who owns the contract when it breaks?
The API vs iPaaS framing is a useful first cut, but the sharper question is about ownership. When something breaks in production — a transformation silently corrupts a record, a retry loop double-charges a customer, a workflow deploys a change nobody reviewed — where does the accountability land?
With an API, the answer is reasonably clear. The owner of the service owns the contract. Version mismatches are a versioning problem. Security issues are an authentication problem. Both are yours to fix, in your codebase, through your deployment process.
With iPaaS, it depends entirely on how that platform treats your artifacts. If your workflow logic lives in a vendor database, every change is a vendor-UI operation. If execution traces live in a vendor console, incident response requires vendor access. If billing spikes when traffic spikes, financial exposure is a function of your traffic pattern, not your purchasing decision.
The teams that end up least surprised by their integration layer are the ones that treat integration logic with the same ownership expectations they’d apply to application code: the logic should be in their repo, the traces should land in their observability stack, and the bill should not move with traffic.
That’s not universally available from iPaaS vendors. But it’s the right bar to set — and platforms that hit it make the “API vs iPaaS” question far less consequential, because they close the gap that makes iPaaS uncomfortable in the first place.
When to use an API, when to use iPaaS, and when to use both
This is the part most comparisons spend too long on, usually in the form of a decision tree that doesn’t survive contact with a real system. A simpler framing:
Use an API when you’re building a surface that external systems will call. Your product exposes capabilities. Those capabilities need authentication, versioning, rate limiting, and documented contracts. An API is the right abstraction.
Use an iPaaS when you’re coordinating across systems you don’t fully own. You’re the consumer of other people’s APIs, not just the producer of your own. The workflow — the sequence, the transformation, the retry logic, the error handling — needs to live somewhere visible and governed. That somewhere is an integration platform.
Most engineering teams at any meaningful scale need both. The API governs the boundary. The iPaaS governs the space between boundaries. The mistake is assuming one substitutes for the other. A well-designed API doesn’t eliminate the need for orchestration, and an integration platform doesn’t replace the need to publish clean interfaces. They work at different layers.
The production-grade version of this answer adds one more requirement: both should be owned artifacts. Your APIs live in your codebase. Your integration logic should too — in Git, versioned, reviewed, observable through your existing stack, with a bill that doesn’t spike when your traffic does.
Koodisi is built for teams running at this standard: workflows in Git, OpenTelemetry traces on every tier from the free plan up, no per-execution billing from Professional onward. If your current integration layer doesn’t pass the ownership test, you can try the Community tier at no cost — 30 active workflows, no credit card, no time limit — to see what production-grade orchestration looks like when it’s treated as software rather than a vendor-side recipe.