On this page
What a well-built REST API gives you
A REST API is the contract between your system and everything that talks to it: your mobile app, your website’s front end, a partner’s platform, an internal dashboard. When that contract is clear, every new client of the API is quick to build. When it isn’t, every integration turns into a round of emails asking what a field means and why an endpoint returned something unexpected.
Our approach is to design the API around your business — orders, bookings, listings, patients, invoices — rather than around database tables. Resources get predictable URLs, standard HTTP methods and status codes, consistent pagination and one error format everywhere. The result is an interface a developer can learn from two or three endpoints and then guess the rest correctly.
Who needs one — and the warning signs
Most businesses reach this point when one system has to serve more than one consumer. Typical examples we see:
- A SaaS startup whose web app and new mobile app need the same data, and the logic is currently duplicated in both.
- A real estate portal that wants brokers or listing partners to push properties in automatically instead of uploading spreadsheets.
- An e-commerce store building a separate app for delivery staff or a warehouse team.
- A clinic group connecting appointment booking, patient reminders and a reporting dashboard to one source of truth.
- A manufacturer exposing order status to distributors without giving them access to the ERP itself.
Warning signs that the current setup is holding you back: every new screen needs a backend change, partners are sent CSV exports by email, endpoints return different error shapes, or nobody is sure which old app versions will break if a field is renamed.
What’s included
- Resource and endpoint design agreed with you before coding starts.
- Implementation with input validation, consistent error responses and pagination.
- Authentication and authorisation — typically OAuth 2.0 or scoped API keys, depending on who the consumers are.
- An OpenAPI specification kept in the repository alongside the code.
- Automated tests for the main flows and the important failure cases.
- A versioning policy, so future changes don’t break existing apps.
- Deployment, logging and basic monitoring so problems surface quickly.
How we deliver it
- Discovery. We map the business objects, who consumes the API, and what each consumer needs to read or change.
- Contract first. We draft the OpenAPI spec and walk through it with you and, where useful, the developers who will consume it.
- Build in slices. Endpoints are delivered in working groups — for example, authentication and listings first, then bookings — so front-end work can start early.
- Security review. Access rules, rate limits and input handling are checked against the OWASP API security risks before launch.
- Launch and handover. Staging and production environments, documentation, and a walkthrough for your team.
Standards and tools we work with
We use proven, widely understood conventions rather than inventing new ones. That usually means JSON over HTTPS with TLS, OpenAPI for the specification, OAuth 2.0 or signed API keys for access, and standard HTTP status codes. For write operations that clients may retry, such as creating an order, we support idempotency keys so a repeated request doesn’t create a duplicate.
The implementation language follows your existing stack where it makes sense — commonly Node.js or Python — and the database choice follows the data. Where events need to reach other systems, we pair the API with webhooks instead of asking consumers to poll constantly.
What affects timeline and cost
The size of an API project depends less on the number of endpoints than on the rules behind them. The main factors are:
- How complex the business logic is — permissions, pricing rules, approval flows.
- Whether the API wraps an existing database or system, or starts clean.
- How many distinct consumer types there are, and whether outside partners need their own access levels.
- Compliance or audit requirements, such as detailed access logs.
- The state of any existing code we need to build alongside.
We scope the work after discovery and share an estimate before building starts.
Common mistakes we help you avoid
- Exposing database tables directly as endpoints, which locks the API to today’s schema.
- Leaving versioning until the first breaking change — when mobile apps already in the field can’t be updated instantly.
- Returning different error formats from different endpoints.
- Writing documentation once at the end, so it’s out of date within weeks.
- Trusting the client: validating input only in the app, not on the server.
Frequently asked questions
Do you build APIs for mobile apps as well as websites?
Yes. A REST API is usually shared by the web front end, mobile apps and any partner integrations, so we design it to serve all of them from one consistent contract.
Can you add an API to our existing system?
Often, yes. We review the existing codebase and database first, then decide whether to build the API inside it or as a separate layer that talks to it. We’ll tell you honestly which is safer.
How do you handle versioning?
We agree a versioning policy at the start — commonly a version in the URL or a header — and add new fields without removing old ones. Breaking changes go into a new version with a documented migration period.
Will we own the code and documentation?
Yes. The source code, the OpenAPI specification and the deployment configuration are handed over to you.
What about GraphQL instead of REST?
GraphQL suits some products, particularly ones with many different front-end views of the same data. For most business APIs and partner integrations, REST is simpler to secure, cache and document, so it’s our default — but we’ll discuss the trade-off for your case.
Talk to us about rest api development
Documented, secured APIs your own apps and outside partners can build against confidently.