API development your own team will not resent using
REST and GraphQL APIs designed for the people who consume them — versioned, documented, authenticated, and monitored from day one.
designed for the people who have to call it
- REST API design
- GraphQL APIs
- Authentication and authorisation
- Best when
- Partners, apps, or internal systems need a clean, versioned, documented interface.
- Not a fit when
- A single internal script would do the job.
- First thing you get
- An API contract with documentation, before implementation begins.
What is API development?
API development is designing and building the interfaces other software uses to talk to your system, typically REST or GraphQL over HTTP, for your own web and mobile apps or for partners. An API is a contract that is costly to break later. We design around what consumers need, with authentication, versioning, rate limits, documentation and monitoring.
An API is a contract, and its cost is asymmetric: getting it wrong is cheap on the day you ship and expensive for every year afterwards, because breaking changes hurt everyone who integrated with you.
We design APIs around what consumers actually need to do rather than mirroring internal table structure, and we build in the parts that get skipped and later missed — authentication, versioning, rate limits, real documentation, and monitoring per endpoint.
What this includes
- 01
REST API design
Resource-oriented APIs with consistent conventions and predictable error handling.
- 02
GraphQL APIs
Schema design where clients genuinely benefit from selecting their own shape of data.
- 03
Authentication and authorisation
OAuth, API keys, and scoped tokens with permissions enforced server-side.
- 04
Versioning
A strategy for evolving the API without breaking existing integrations.
- 05
Documentation
OpenAPI specs and usable docs generated from the implementation, so they stay true.
- 06
Rate limiting and monitoring
Protection against abuse plus per-endpoint latency and error visibility.
Situations we see most often
Exposing your platform to partners
A public or partner API that third parties integrate with and depend on.
Backend for web and mobile
One well-designed API serving several clients rather than a separate backend per surface.
Fronting a legacy system
A clean modern interface over an older system that has no usable API.
Connecting internal systems
Integration layers so your own tools can talk to each other reliably.
What to know before you start
REST or GraphQL: which should you use?
REST suits most cases. It is simple to cache, monitor and debug, and every developer who consumes it already understands it. GraphQL earns its extra complexity when many different clients, such as several apps and partner integrations, need genuinely different shapes of the same data.
We choose based on who consumes the API and how, not on fashion, and some systems sensibly use both.
What does good API design look like?
It is designed around what consumers need to do, not around the internal database tables. Resources and errors are consistent and predictable, every endpoint is authenticated and authorised, and the contract is written down before implementation starts.
Documentation is an OpenAPI specification generated from the code, so it cannot drift from what the API actually does, and consumers can try requests against it directly.
How do you change an API without breaking consumers?
By preferring additive changes, such as new fields and new endpoints, which existing consumers can ignore. When a breaking change is truly unavoidable, it goes into a new version, and the old version keeps working through a stated deprecation window with clear notice.
Monitoring per endpoint shows who still uses an old version, so it is retired based on evidence rather than a guess.
How are APIs secured?
With standard, well-tested mechanisms: OAuth 2.0 or signed tokens for authentication, role- and scope-based authorisation on every endpoint, rate limiting to prevent abuse, input validation, and logging of who called what. Partner keys can be issued, scoped and revoked individually.
How is an API tested?
Automated tests run against the contract on every change: each endpoint's success and error cases, authorisation rules, and validation. Contract tests confirm the implementation still matches the OpenAPI specification, so consumers are never surprised.
Load tests check behaviour under realistic peaks before launch, and monitoring per endpoint in production shows latency and error rates as real consumers use it.
How do you document an API for partners?
With an OpenAPI specification generated from the code, published as interactive documentation where developers can read each endpoint and try requests. A getting-started guide, authentication examples and a sandbox environment let a partner integrate without a call.
What drives the cost of API development?
API cost follows how many consumers it serves and what sits behind it. These factors move it most.
| Factor | Effect | Why it matters |
|---|---|---|
| Number of resources and operations | High | Every resource, operation and validation rule must be designed, built, documented and tested. |
| Systems behind the API | High | Fronting legacy systems or several databases adds integration and error-handling work. |
| Consumers and access model | Medium | Partner access with scoped keys, quotas and onboarding needs more than an internal API. |
| REST or GraphQL | Medium | GraphQL adds schema design, query cost controls and caching work over plain REST. |
| Versioning and compatibility | Medium | Supporting multiple versions during deprecation windows adds testing and maintenance. |
| Monitoring | Low | Per-endpoint metrics, logs and alerts are modest to add and essential once partners depend on you. |
What a typical engagement looks like
- 011–3 weeks
Discover
Process map
- 022–4 weeks
Design
Interactive prototype
- 03two-week cycles
Build
Working software each cycle
- 04ongoing
Ship & support
Automated pipeline
What we build it with
- Frameworks
- NestJSNode.jsExpress
- Specification
- OpenAPIGraphQLJSON Schema
- Security
- OAuth 2.0JWTRate limiting
Questions we get asked
01REST or GraphQL?
REST for most cases — it is simpler to cache, monitor, and debug, and every consumer already understands it. GraphQL earns its complexity when you have many different clients needing genuinely different shapes of the same data, or deeply nested relationships that would otherwise mean many round trips.
02How do you handle breaking changes?
By avoiding them where possible through additive design, and by versioning explicitly where they are unavoidable — with the old version supported through a stated deprecation window rather than switched off.
03Do you provide documentation?
Yes. OpenAPI specifications generated from the implementation, so the documentation cannot silently drift from the actual behaviour.
04Can you build an API in front of our legacy system?
Yes. An API layer in front of an older system lets new apps and partners integrate cleanly while the legacy code stays untouched, and it is often the first step of a gradual modernisation.
05How do partners get access?
Through individually issued, scoped credentials with documentation and a test environment, so each partner can be onboarded, monitored and revoked independently.
06Can you build webhooks for partners?
Yes. Signed webhook events with retries and a delivery log, so partners can react to changes in your system without polling, and you can see whether each event arrived.
07Do you build SDKs for API consumers?
Where it helps adoption, yes. Client libraries can be generated from the OpenAPI specification for common languages, so they stay in step with the API.
08How do you handle API performance under load?
Through pagination, caching for data that changes rarely, efficient queries, and rate limits that protect the system. Load tests before launch confirm behaviour at realistic peaks, and per-endpoint monitoring catches slowdowns early.
Adjacent capabilities
Tell us what you are building.
Share the problem and we will come back with an approach, a rough shape of the work, and what it would take to deliver it.