Custom API Development
APIs
others can rely on.
Custom API development for Australian businesses building platforms, partner integrations, or internal services. REST, GraphQL, webhooks, auth, observability — built with the engineering rigour that turns an API into a product.
Quick answer: custom API development means building APIs your business owns — for a SaaS product, a partner integration program, internal microservices, or to expose business data to third parties under controlled terms. Different from API integrations (consuming someone else’s APIs); API development is creating the APIs others rely on.
Modern API development practice is well-documented; the OpenAPI Specification is the de-facto standard for REST API contracts, and RFC 6749 (OAuth 2.0) is the canonical reference for the auth patterns we deploy. APIs are intimately tied to our SaaS development, internal tools, and ecommerce development practices — most serious products need both.
When you need a custom API
- You’re building a SaaS and customers need to integrate with your platform programmatically
- You have partner relationships that involve programmatic data exchange — resellers, channel partners, integrators
- Your internal services have grown to the point where structured contracts between them save more time than they cost
- You want to expose data to third-party developers under controlled terms
- You need a programmatic interface for AI agents, automation tools, or partner platforms to interact with your business
What we build
- REST APIs. Default for public and partner-facing APIs. Versioned, documented via OpenAPI, with proper auth, rate limiting, and audit logging.
- GraphQL APIs. When consumers benefit from flexible querying and you control both ends of the contract.
- Webhook delivery systems. The reverse path — pushing events to consumers when things happen in your system, with proper retry logic, signature verification, and delivery monitoring.
- Internal microservices. Service-to-service APIs for systems that have grown past a single monolith.
- SDK and documentation. Reference implementations in common languages (TypeScript, Python, PHP), interactive API playgrounds, and developer onboarding flows.
- AI-backed endpoints. APIs that wrap LLM-driven capabilities with proper engineering — evals, observability, fallbacks — so they work in production.
What good API development includes
The areas where most APIs we audit have problems — and where we put the engineering effort up front:
- Auth and access control. OAuth 2.0 or API keys with scopes; explicit checks at every endpoint, not assumed from middleware.
- Rate limiting. Per-key limits with proper headers; Redis-backed token bucket; documented limits per tier.
- Idempotency. Write endpoints accept idempotency keys so retried requests don’t duplicate.
- Versioning policy. Documented at launch; partners need to know how long any version they integrate against will be supported.
- Observability. Per-endpoint latency and error rate, with alerting; structured logs that let you debug a specific request three months later.
- Documentation. OpenAPI specs as source of truth; auto-generated reference docs; clear examples; honest description of failure modes.
Common questions
What is custom API development?
Building APIs your business owns and operates — for a SaaS product, a partner integration platform, internal microservices, or to expose your business data to third parties under controlled terms. Different from API integrations (consuming someone else’s APIs), API development is creating the APIs others consume.
REST vs GraphQL — which should I use?
REST is the boring, correct answer for most public APIs and partner integrations — broadly understood, well-tooled, easy to operate. GraphQL wins when API consumers need flexibility (combining data across many resources without N+1 calls) and you control both ends. We build both regularly and choose based on use case.
How much does API development cost?
A focused first-version API for a partner program or internal service: $25,000–$80,000. A serious public API with SDK, documentation, rate limiting, and developer onboarding: $80,000–$250,000+. Cost scales with the surface area of the API and the operational expectations (uptime SLA, audit logging, etc.).
Do you handle API authentication and security?
Yes — auth is one of the most-bug-prone areas of any API and gets serious engineering attention. Default patterns: OAuth 2.0 for partner APIs, API keys with scopes for service-to-service, JWT for in-platform auth. With rate limiting, audit logging, and explicit access control at every endpoint.
Can you integrate AI capabilities into our API?
Yes. We build AI-powered API endpoints regularly — classification, extraction, summarisation, RAG-backed Q&A. The API surface is the easy part; the engineering around it (evals, observability, fallbacks, cost controls) is where most of the work lives. We have a separate AI automation service for the AI engineering side.
How do you handle API versioning?
Default: URL-based versioning (/v1/, /v2/) for major changes, additive changes within a version, and clear deprecation timelines. We document version policy at API launch — partners need to know how long any version they integrate against will be supported.
Do you produce API documentation?
Yes — API docs are part of the deliverable, not an afterthought. We use OpenAPI/Swagger specs as the source of truth and generate human-readable documentation from them. For public APIs, we also build interactive playgrounds where useful and provide reference implementations in common languages.
How do you handle API rate limiting?
Standard pattern: per-key rate limits with appropriate headers (X-RateLimit-Remaining, X-RateLimit-Reset), Redis-backed token bucket implementation, and 429 responses with Retry-After when limits are hit. Critical for any public API to prevent one consumer affecting others.
Let’s build something
The right system,
built once, properly.
If your business is ready to scale beyond what off-the-shelf tools can support — we should talk.