API Development Services
APIs and integration layers that connect systems reliably, with documentation and error handling.
What is API development?
API development is building the interfaces through which software systems exchange data — endpoints, authentication, data formats, error handling and documentation. It covers both APIs you publish for others to consume and integration layers that connect your systems to third-party services such as payments, logistics or messaging.
Why this matters
Integrations fail in predictable ways: the other system is down, the response is malformed, the same webhook arrives twice, or a rate limit is hit at month end. An API built without handling those will work in testing and lose data in production. That handling is most of the real work.
Where integrations break
- Duplicate webhooks create duplicate orders because handlers are not idempotent.
- A third-party outage causes silent data loss with no retry.
- Rate limits are hit during bulk operations and records are skipped.
- There is no documentation, so the consuming team guesses at the contract.
How we build APIs
Design the contract first and document it. Validate input at the boundary, return consistent structured errors, make write handlers idempotent, and use queues with backoff for anything crossing a network. Log enough to reconstruct what happened, and version the API so consumers are not broken by changes.
What api development includes
Every engagement is scoped to your situation, but these are the components the work is built from.
- Contract-first designEndpoints, payloads and error formats documented before implementation.
- AuthenticationToken or OAuth-based access with scopes and rotation handled properly.
- Idempotency and retriesSafe repeat delivery and backoff so transient failures do not lose data.
- Rate limitingProtection on your endpoints, and respect for limits on the systems you call.
- VersioningVersion strategy and deprecation path so consumers are not broken silently.
- MonitoringStructured logs, failure alerts and the means to replay failed events.
What changes for your business
- Integrations that survive third-party downtime.
- No duplicate or lost records from repeated webhooks.
- Documentation your partners and internal teams can rely on.
- Failures that alert someone instead of being discovered in a month-end reconciliation.
Technology and platforms
Chosen to match how the work will actually be maintained, not by preference.
How the work runs
Each stage ends with something you can review, so course corrections happen early rather than at handover.
- Map the processHow the work is done today, including the exceptions people work around.
- Model the dataEntities, relationships and permissions agreed before feature work begins.
- Build in stagesA useful first release, then iteration with the people who actually use it.
- IntegrateConnections to the systems you already run, with proper error handling.
- Deploy and documentRepeatable deployment, monitoring, and documentation for whoever maintains it.
Industries we apply api development in
The technical work is often similar across sectors. What differs is what customers need to see before they act.
What drives the cost
We publish what moves the price rather than a headline figure, because the figure without the drivers is not comparable.
- Number of endpoints and integrations
- Authentication and security requirements
- Data volume and sync frequency
- Documentation and partner support needs
Why work with SWT Company
Scoped before it is quoted
We ask what the business needs before proposing work. A quote given before that conversation is a guess.
Measurement first
Tracking — including calls and WhatsApp — is verified before spend, because every later decision depends on it.
No claims we cannot support
No ranking guarantees, no invented results, no numbers we cannot evidence.
You own everything
Domain, hosting, repository, analytics and ad accounts stay in your name.
Built to be handed over
Documentation and clear structure, so you are never dependent on one supplier.
Mobile-first in practice
Designed at phone width and tested on mid-range devices over mobile data.
Projects and case studies
We publish case studies only where a client has agreed and the results can be evidenced. None are published yet, because no verified client data was supplied for this build and inventing results is not something we will do. Ask and we will arrange references in your sector directly.
API Development — frequently asked questions
REST is simpler to cache, monitor and debug and suits most integrations. GraphQL helps when many clients need different shapes of the same data. Default to REST unless there is a specific reason.
Authentication with scoped tokens, transport encryption, input validation, rate limiting and audit logging. Secrets stay server-side and are rotated.
It means processing the same request twice has the same effect as once. Networks retry and webhooks duplicate, so without it you get double orders and double charges.
Yes — an OpenAPI specification plus practical examples. Undocumented APIs cost more in support time than the documentation costs to write.
Related services
Related industries
Related solutions
Related comparisons
Talk to us about api development
Call or message for anything urgent. Otherwise the form reaches the same place.
Get a quote for api development
A short conversation is usually enough to establish scope, timeline and a realistic range.