API development and integrations.

API design covers endpoints, data schemas, validation, authentication, error handling, pagination, rate limits, idempotency, and versioning where applicable. Those decisions are made before implementation, because they are the parts that are expensive to change once something else is calling the API.

Idempotency and versioning matter most in payment and integration work. A retried request must not create a second order, and a change to the contract must not break the systems already depending on it. Both are designed in rather than added under pressure later.

Third-party integrations are designed around the provider's authentication model, API limits, webhook behaviour, failure modes, and reconciliation requirements. The provider's constraints set the shape of the integration, so they are read before the work is estimated.

Where a provider's documentation does not describe a failure case, the integration records what it received and keeps the state recoverable, so a discrepancy can be investigated against evidence.

In Kenya the common requirement is M-Pesa through the Safaricom Daraja API, across its modes: STK push for customer-initiated payments, C2B for paybill and till numbers, B2C for disbursements such as refunds and payouts, and transaction status queries for reconciliation. Pesapal, Flutterwave, and Stripe are integrated where they fit the product and its market.

Payment integrations are built around delayed callbacks, cancelled prompts, duplicate notifications, and timeouts, because those determine whether records stay correct. Webhook processing includes signature verification, idempotency, retries, structured logging, and reconciliation against the system of record.

Authentication may use API keys, OAuth 2.0, signed requests, tokens, or another mechanism appropriate to the system and to who is calling it. Credentials are kept out of client-side code, and sensitive values are excluded from logs.

Transport is HTTPS throughout, with input validation, rate limiting, and logging, following OWASP guidance. Where an existing API is being taken over, it is audited against the same list before changes are made, and the findings are shared before any refactoring is quoted.

APIs can be delivered with OpenAPI documentation, example requests and responses, integration notes, and automated tests appropriate to the project, so another team can integrate without depending on a conversation with us.

Monitoring and alerting cover failure rates, latency, and integrations that start failing quietly. That is the usual way an integration breaks: not with an outage, but with a rising error rate that nobody is watching until a reconciliation does not balance.