How to integrate APIs is usually taught as a sequence of technical steps: pick a protocol, authenticate, handle the response. That sequence can work perfectly and still create a mess, because the real risk isn't the connection; it's what happens when both systems keep their own copy of the same record, and nobody decides which one is right. This guide covers the steps, and then the decision that actually matters more.
How to Integrate APIs: The Technical Steps
Choosing a protocol: REST, GraphQL, or SOAP. Most modern API integration steps start with REST, resource-based and widely supported. GraphQL suits a client that needs to request exactly the data it wants in one call. SOAP still shows up in older enterprise systems that were built around its stricter contracts.
Authentication and rate limits. An api integration guide worth following treats authentication as a first-class step, not an afterthought, and accounts for rate limits from the start: a system that works in testing can fail in production the moment real traffic hits a limit nobody planned around. A batch sync that retries automatically on a schedule can hit a rate limit in a way a handful of manual test calls never surfaces, which is exactly why this belongs in the design conversation rather than getting discovered after go-live.
The Steps Aren't What Usually Breaks an Integration
Connecting two systems and keeping them in agreement are different problems. Roy Fielding's 2000 doctoral dissertation at UC Irvine, which introduced REST as an architectural style, frames it around scalability and consistency in a distributed system, not just connectivity, a distinction most implementation tutorials skip on the way to a working API call. A technically correct integration built without an ownership decision behind it still produces two disagreeing copies of the truth.
Protocols and Mechanics, Compared
REST
What it's good at: Simple, resource-based, widely supported
What it doesn't solve: Doesn't decide which system owns a field
GraphQL
What it's good at: Lets a client request exactly the data it needs
What it doesn't solve: Still needs an explicit ownership decision behind it
SOAP
What it's good at: Strict contracts, common in older enterprise systems
What it doesn't solve: Heavier, but more reliable at preventing drift
Webhook
What it's good at: Pushes a change the moment it happens, instead of polling
What it doesn't solve: Only useful if the receiving system acts on it and updates its own copy
The Question That Actually Matters: Who Owns This Field?
Which system is the source of truth for this record?
Why it matters: Without an answer, both systems assume they are
What's the sync frequency?
Why it matters: A daily sync means the second system is always up to a day stale
What happens on failure?
Why it matters: Retry logic decides whether a dropped update gets recovered or silently lost
Who resolves a conflict when both systems changed the same record?
Why it matters: Without a rule, whichever system synced last wins by accident, not by design
None of these four questions is hard to answer once someone actually asks them. What breaks integrations is skipping straight from "the API call works" to production, without anyone having answered them at all. A source-of-truth decision made after the second system starts disagreeing with the first is a much more expensive conversation than the same decision made before either system writes a single record.
In practice, the source-of-truth answer is rarely the same for every field in the integration. A CRM might reasonably own customer contact details while an ERP owns pricing and stock levels, with the integration syncing each field in whichever direction matches that split. Treating the whole integration as having one owner, rather than deciding it field by field, is a common shortcut that surfaces as exactly the kind of quiet disagreement this guide is about.
Where Burhani Fits
Our application development work defines field ownership, validation, and recovery before writing an integration, not after. This fits a business connecting two systems that both need to stay trustworthy after the connection goes live. It's not a fit for a one-off data pull where no one will ever check the two systems against each other again.
FAQs on How to Integrate APIs
How do you integrate two APIs?
Choose a protocol (typically REST), authenticate, and handle rate limits and error responses. That covers the mechanical steps of how to integrate APIs. The step most guides skip is deciding, before any of that, which system owns each field and how often the copies sync.
What is the difference between REST and GraphQL?
REST exposes fixed resources through standard endpoints and is widely supported. GraphQL lets a client specify exactly the fields it wants in a single request, which reduces over-fetching but adds its own setup complexity. Neither one decides field ownership for you.
What is retry logic, and why does it matter?
Retry logic is what happens when an API call fails partway through: whether it's automatically attempted again, queued, or silently dropped. Without defined retry logic, a failed sync can leave two systems permanently out of agreement with no record that anything went wrong.
How often should two integrated systems sync?
It depends on how stale a difference the business can tolerate. A daily sync is fine for a report that gets checked once a day; an operational record both teams act on in real time needs a much shorter sync frequency, or a webhook that pushes changes immediately.
What happens if both systems change the same record?
Without an agreed conflict rule, whichever system happens to sync last overwrites the other silently, which means the result is decided by timing rather than by which change should actually win. Defining that rule upfront is part of the ownership decision an integration needs before going live.
The Bottom Line
A working connection and an agreed source of truth are two different achievements. The protocol you choose barely matters next to whether both systems, and the people relying on them, agree on which one is right when they disagree.
Talk to our team about the two systems you're connecting and which one should be the source of truth.
