IONICWEBCREATOR
API Development

An API is a promise you have to keep for years

Once someone integrates, your API is infrastructure. Every field name is a commitment and every breaking change is somebody's outage. We design APIs with that lifespan in mind — clear resources, honest errors, real versioning, and documentation generated from the contract rather than written beside it.

Book a discovery callAll services
  • Contract-first
  • Versioned properly
  • Docs from the schema

Most API problems are not performance problems. They are ambiguity problems: an endpoint that returns a different shape depending on a query parameter, an error that says 500 when it means 'you sent the wrong date format', a field that was quietly removed.

Contract first

The schema is written before the implementation, reviewed with the people who will consume it, and used to generate both the runtime validation and the documentation. The docs cannot drift from the API, because they are derived from the same source.

Designed for failure

Rate limits that return the right headers. Idempotency keys so a retried write does not double-charge. Cursor pagination that survives inserts. Webhooks that are signed, retried with backoff, and observable by the receiver. These are the details integrators judge you on.

  • Consistent, typed error responses with a machine-readable code
  • Versioning with a deprecation policy people can plan against
  • Authentication and scopes that are simple to reason about and hard to misuse
Problems we solve

What this work is for

The situations teams are usually in when they bring us this problem.

  • Breaking changes ship by accident

    No contract, no version, no deprecation window — and someone's integration stops working overnight.

  • Retries cause duplicates

    Without idempotency, a network blip becomes a second order or a second charge. It is preventable in a day.

  • Documentation nobody trusts

    Hand-written docs drift within a sprint. Generate them from the schema and the problem disappears.

Our approach

How the work runs

The same sequence on every engagement, so there are no surprises in week three.

  1. Design the contract

    Resources, shapes, errors and auth agreed with real consumers before implementation starts. Changing a schema is cheap; changing a live API is not.

  2. Implement against it

    The schema drives validation and types, so the implementation cannot quietly diverge from what was agreed.

  3. Harden

    Rate limiting, idempotency, pagination, signed webhooks, and a consistent error model — the parts people only miss when they are absent.

  4. Publish

    Generated reference documentation, a sandbox, and a versioning policy your integrators can plan around.

What's included

What you get

Concrete deliverables — all of it yours to keep, run, and hand to another team.

  • API contract

    An OpenAPI schema, reviewed with consumers, that generates both validation and docs.

  • Implementation

    Typed handlers with a consistent error model and enforced input validation.

  • Reliability features

    Rate limiting, idempotency keys, cursor pagination, and signed, retried webhooks.

  • Auth

    Keys, OAuth or JWT with scopes — chosen for your integrators, not for fashion.

  • Developer experience

    Reference docs, examples, a sandbox, and a deprecation policy in writing.

Technology

What we build it with

Chosen for the problem, not for novelty.

We are not tied to any of these. If your team already runs something that works, we build with it.

API

Schema-first with Fastify and Zod, so the contract, the validator, and the types are one artefact.

  • Fastify
  • TypeScript
  • Zod
  • OpenAPI
Data

Predictable queries and indexes chosen from the slow query log, not from intuition.

  • PostgreSQL
  • Prisma
  • Redis
  • Cursor pagination
Integration

Webhooks are an API too — signed, retried, and inspectable, or they will be the thing that breaks trust.

  • Signed webhooks
  • Idempotency
  • Rate limiting
  • OpenTelemetry
Questions

Before you get in touch

The questions that come up in almost every first conversation.

REST or GraphQL?

REST for public and partner APIs — it is cacheable, debuggable, and every integrator already understands it. GraphQL is a good fit when a first-party client needs flexible reads. We will make the case either way rather than default.

Can you document an API we already have?

Yes, and it is a common starting point. We capture the real behaviour into a schema, which typically surfaces several inconsistencies worth fixing before they are written down as promises.

How do you handle versioning?

Additive changes are shipped without a version bump. Breaking changes get a new version, a written deprecation window, and monitoring so you can see who is still on the old one before it is switched off.

Tell us what you're building.

Bring the problem, not a spec. We will tell you honestly whether we are the right team and outline a concrete first step — no obligation, no sales theatre.

Book a Discovery Callsupport@ionicwebcreator.com