API development and integration services: REST APIs in Laravel and PHP

There are two jobs here, and most projects need both. Building an API means exposing your data and actions to a mobile app, a front end, a partner or another of your own systems, with authentication, validation and documentation. Integrating an API means connecting your system to someone else's: pushing invoices to accounting, pulling trades from a trading platform, answering clients through a bot, reading documents with an AI model.

This is for businesses with a Laravel or PHP application that needs to connect to the outside world, startups that need a backend for a mobile app, and teams whose current integration fails silently and loses data. Payments and AI features have their own pages, because their details differ: see payment gateway integration and OpenAI and ChatGPT integration.

A good API is predictable. My approach to Laravel API development is consistent resource naming, versioned routes (/api/v1/...), validation through Form Requests so every error comes back in the same JSON shape, and API Resources so the response format does not change every time a database column does. Pagination, filtering and sorting follow one convention across all endpoints, which saves your app developers a lot of guessing.

For authentication, Laravel Sanctum covers most cases: tokens for a first-party mobile app, or cookie-based sessions for a single-page app on the same domain. Passport, which is a full OAuth2 server, is worth its extra complexity only when third parties need to authorize access to your users' data. Rate limits, CORS rules and token abilities are set per client rather than left at the defaults.

As a mobile app backend, the API also covers what mobile developers expect: device registration for push notifications through Firebase Cloud Messaging, image uploads with size and type checks, and responses small enough to be quick on a weak connection.

The happy path of an integration often takes a day. The rest of the work is what happens when the other side is slow, down, rate-limited or returns something its documentation never mentioned. The rules I build to:

• Never call a slow API inside a user's request. Calls run as queued jobs, so nobody waits on someone else's server.
• Retry with backoff, not in a tight loop. Laravel's job middleware for rate limiting and exception throttling spaces retries out and respects the provider's limits.
• Make every operation idempotent. A retried webhook or job must not create a second invoice or a second payment. Unique keys and a record of processed events prevent it.
• Verify webhooks. Incoming requests are checked against the provider's signature, usually an HMAC of the payload, before anything is processed.
• Stage, map, then write. Outside data lands in staging tables and passes through field and entity mapping before it reaches your real records, and every call is logged so a failure can be traced and replayed.
• Tell a person. When retries run out, someone gets an alert instead of finding the gap a month later.

These are real and in production. On a brokerage risk platform, the MT5 Manager Web API for trading data, plus a Telegram bot that verifies signed payloads and asks for a PIN before sensitive actions. On an AI invoice capture project across four business systems, a staged and logged accounting sync, documented purchasing REST endpoints and the OpenAI API for reading invoices. Elsewhere: the Gmail API and Firebase Cloud Messaging for an email campaign SaaS, and Google Business Profile APIs on a listing management platform.

If your provider is not on that list (Zoho, QuickBooks, Xero, Shiprocket, WhatsApp Business, Twilio and so on), the work has the same shape: read their documentation, test in their sandbox, and build the client with the failure rules above. I will tell you early if an API has limits that make your idea hard, such as low rate limits or a missing endpoint.

You work with the engineer who designs the endpoints and writes the integration code, not a project manager. That matters with APIs, because most problems hide in the details: a field the documentation describes wrongly, a timestamp in an unexpected timezone, a sandbox that behaves differently from production. I am based in India and work remotely with clients in different time zones; we agree on update times at the start.

Because I also build back offices and admin panels, I design APIs with the whole system in mind. The same business rules apply whether an order arrives through the admin panel, the mobile app or a webhook, so data stays consistent however it gets in.

The main drivers are the number of endpoints or integrations, the quality of the third party's documentation and sandbox, the authentication method (a static API key is simple, OAuth with token refresh is more work), the data mapping involved, the volume the sync must handle, and whether data flows one way or both. Two-way sync with conflict handling is always the biggest item.

For a new API I start from the screens or the client app that will use it; for an integration, from the provider's documentation and a test account. Either way you get a fixed quote after a short call or written brief.