# Interfaces your teams can depend on.

API design & integration

Create versioned contracts, validate payloads and handle authentication, throttling and backwards compatibility.

## A contract consumers can rely on

Illustrative workflow.

- Request: Typed fields and a stable resource identifier
- Response: Documented result and error behaviour
- Evolution: Compatibility rules and a deprecation path



## The contract includes the failures

Design APIs around business capabilities, predictable validation and stable error semantics. Test consumers against the contract so changes can be released without guessing which integration might break.

Illustrative scenario, not a customer case study.

A portal and several integration clients update on different schedules.

Separate additive changes from breaking changes. Validate requests at the boundary, document optional fields and use consumer examples to verify compatibility before deployment.

Verification: Run contract checks against representative supported client versions and malformed payloads.

## Predictable contracts for ordinary and failed requests.

### Contracts and versions

Define requests, responses and error behaviour that consumers can validate before deployment.

### Identity and limits

Apply authentication, authorisation and rate controls at each exposed interface.

### Consumer compatibility

Test existing clients against changes and provide a clear transition for breaking updates.

## A sample response cannot explain an API

### Publish an endpoint and a sample response

Consumers must infer pagination, retries, validation errors and compatibility from production behaviour.

### Document the complete interaction

Version schemas, test representative failures and specify which commands can be retried safely.

## What needs attention in your system?

Select the areas you want to discuss. The HTML page can download your selections.

- [ ] Contracts and versions: Define requests, responses and error behaviour that consumers can validate before deployment.
- [ ] Identity and limits: Apply authentication, authorisation and rate controls at each exposed interface.
- [ ] Consumer compatibility: Test existing clients against changes and provide a clear transition for breaking updates.

## Does every change need a new API version?

No. Distinguish compatible additions from changes that alter meaning or remove behaviour. Versioning should make the migration clear, not replace compatibility analysis.