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API Development Services

API Development Services - REST, GraphQL & beyond.

We design and build custom APIs - RESTful, GraphQL, gRPC, and webhook systems - with OAuth 2.0 authentication, rate limiting, versioning, OpenAPI documentation, and the infrastructure to handle production traffic from day one.

Explore API Types
Trusted by businesses worldwide
REST & GraphQLBoth architectures
120+Endpoints built (BeesApp)
OpenAPIFull documentation
OAuth 2.0Auth standard
Overview

APIs built for developers to adopt and systems to rely on.

An API (Application Programming Interface) is the contract between your backend and every system that connects to it - your mobile app, your web frontend, your third-party integrations, your partners, and your customers' own applications. A poorly designed API breaks all of these simultaneously. A well-designed one is a competitive asset that accelerates development across every team touching your product.

We design and build APIs that are consistent (predictable resource names, HTTP methods, and error formats), secure (OAuth 2.0, JWT, rate limiting, and input validation from day one), documented (OpenAPI/Swagger spec and interactive docs so developers can adopt without asking questions), and versioned (so you can evolve the API without breaking existing integrations).

Every API we ship covers the full lifecycle: design, development, testing, documentation, security review, deployment, and monitoring. We also build the third-party integrations your product needs - Stripe, Twilio, HubSpot, WhatsApp, Google APIs, and custom partner APIs.

01
SaaS backends
Multi-tenant API serving web app, mobile, and partner integrations.
02
Mobile API
RESTful backend for iOS and Android apps with offline sync.
03
Public APIs
Developer-facing APIs with keys, docs, and rate limiting.
04
Third-party integrations
Connect your system to Stripe, HubSpot, WhatsApp, and more.

4 API architectures we build.

Each suits different use cases, we recommend the right one for your product.

Most Common · Default Choice

REST API

REST organises endpoints around resources (/users, /orders, /products) with HTTP methods defining the action. It is the right default for public APIs, mobile backends, and partner integrations: HTTP caching works naturally with GET requests, tooling is mature, and every developer already knows the pattern. Use REST when your consumers are external, your data model is resource-based, and you want maximum adoption.

HTTP methodsJSON responsesCacheable GETsOpenAPI specVersioned URLs
Frontend-Optimised

GraphQL API

GraphQL exposes a typed schema - the client specifies exactly which fields to fetch in a single query, eliminating the over-fetching and under-fetching problems common with REST. A mobile app needs fewer fields than the web dashboard; both query the same endpoint efficiently. Best for data-rich applications with multiple client types, with query depth limits, complexity analysis, and DataLoader to prevent N+1 queries.

Typed schemaSingle endpointNo over-fetchingSubscriptionsDataLoader
Service-to-Service

gRPC API

gRPC uses Protocol Buffers over HTTP/2 for binary serialisation - 5–10× faster than JSON over HTTP/1.1 for equivalent payloads. It is optimal for internal service-to-service communication in microservices architectures where latency and throughput matter, and it generates typed client SDKs automatically from the proto definition. Not suitable for public browser clients without a REST gateway in front.

Protocol BuffersHTTP/2Bi-directional streamingAuto SDK genmTLS
Event-Driven

Webhooks & Event APIs

Webhooks invert the request model: your server pushes an HTTP POST to a client-registered URL when an event occurs - payment confirmed, order shipped, user signed up. We implement webhook systems with HMAC payload signing, idempotency keys to prevent duplicate processing, retry logic with exponential backoff, and a dead-letter queue for failed deliveries. We also build WebSocket APIs for real-time bidirectional communication.

HMAC signingIdempotency keysRetry + backoffEvent schemaWebSocket

Integrations, specialised.

Three deeper services under this area, for connecting outward rather than exposing your own API.

01

API Integrations

Connecting your product to payment processors, mapping services, communication tools, and AI models - with circuit breakers, OAuth 2.0, and rate-limit handling built in.

02

Payment Gateway Integration

Stripe, PayPal, Adyen, and multi-gateway orchestration, with tokenized checkout, idempotent webhooks, and 3DS2 support for regulated markets.

03

SaaS Integrations

Syncing your product with the CRM, ERP, and SaaS tools your customers already run, built on native APIs rather than a fragile middleman platform.

9 API services we deliver.

Every type of API work, from greenfield design to legacy modernisation.

Custom API design & architecture

Resource naming, endpoint structure, HTTP status codes, error format standardisation, and API contract definition in OpenAPI 3.0 before development starts.

RESTful API development

Full-stack REST API development with Node.js, FastAPI, or Django - including authentication, input validation, pagination, filtering, and comprehensive error handling.

GraphQL API development

Schema design, resolver implementation, DataLoader for batched queries, subscriptions for real-time data, and query complexity limits to prevent abuse.

Webhook system development

Event dispatch, HMAC payload signing, receiver endpoint handling, retry infrastructure with exponential backoff, dead-letter queues, and a delivery dashboard for debugging.

Mobile API development

RESTful APIs purpose-built for iOS and Android apps - optimised payloads, offline sync endpoints, push notification triggers, and independent versioning.

Third-party API integration

Connect your system to Stripe, Twilio, SendGrid, HubSpot, WhatsApp Business API, Google Maps, Salesforce, and others - with error handling, retry logic, and webhook receivers.

API documentation

OpenAPI 3.0 specification, interactive Swagger UI or Redoc, code samples in 4 languages, and a developer portal, so external teams adopt without hand-holding.

API testing & monitoring

Unit, integration, contract, and load testing. Production monitoring via uptime checks, error rate alerts, and p95/p99 latency dashboards, failures surface before users report them.

Legacy API modernisation

Migrate SOAP/XML APIs to REST, add versioning to unversioned APIs, document undocumented endpoints, and refactor brittle integrations, without taking the system offline.

6 security layers in every API.

Security built into the design, not patched on after a breach.

OAuth 2.0 & JWT

OAuth 2.0 handles token issuance and scope. JWTs carry signed, stateless claims, no database lookup per request. Short-lived access tokens (15 min) with refresh rotation limit exposure if a token is stolen.

Bearer JWT · Refresh rotation

Rate limiting

Three-tier limits protect against abuse and DoS: unauthenticated requests get 60/hour, authenticated users 5,000/hour, and premium tiers 15,000/hour. Rate-limit headers let clients self-throttle before hitting 429s.

60 → 5k → 15k req/hr

Input validation & sanitisation

Every parameter, body field, and header is validated against a strict schema before reaching business logic. SQL injection, XSS payloads, and malformed data are rejected at the boundary with a clear 400.

Schema validation · 400 on fail

CORS & HTTPS enforcement

CORS policies specify exactly which origins can call the API, never wildcard in production. All traffic is HTTPS; HTTP redirects to HTTPS or returns 301. TLS 1.3 minimum.

CORS allowlist · TLS 1.3

API key management

For public APIs and B2B integrations, we build a key system with scoped permissions, rotation, revocation, per-key rate limits, and an audit log showing which key made which request.

Scoped keys · Audit log

Webhook HMAC signing

Every outgoing webhook payload is signed with HMAC-SHA256 using a shared secret. Receivers verify the signature before processing, preventing forged delivery. Each event carries a unique ID for idempotency.

HMAC-SHA256 · Idempotency

Proof, not promises.

120+ API endpoints built for a multi-vendor SaaS platform operating in Saudi Arabia.

All Case Studies
  • API Development
  • FastAPI
  • Next.js
  • Multi-vendor Marketplace
Client
BeesApp
Industry
Retail Tech
Location
Saudi Arabia
Timeline
6 Months

120+

REST API Endpoints Built

BeesApp's legacy system ran on a broken patchwork of PHP and Django with no consistent API design. We rebuilt the entire API layer on FastAPI - 120+ endpoints covering product catalogue, order management, multi-vendor payouts, inventory sync, user authentication, and admin operations. The API powers both the Next.js web frontend and the Flutter mobile app simultaneously, with full OpenAPI documentation and automated testing before every deployment.

120+

API endpoints built

99.9%

Platform uptime

74%

Faster load time

BeesApp platform rebuild
Read Full Case Study

How we build your API.

A 5-step process from contract to monitored production API.

01

Discovery & scoping

Map all consumers (web, mobile, partners), data flows, authentication requirements, and integration points before any design starts.

Consumer-first scoping
02

API contract design

OpenAPI 3.0 spec written before code - endpoint names, request/response schemas, error codes, and authentication flows locked in and reviewed.

OpenAPI spec first
03

Development

Implementation with auth, validation, rate limiting, and pagination. Every endpoint ships with unit and integration tests; frontend teams get mock servers to build against.

Tested on every endpoint
04

Security & load testing

OWASP API Security Top 10 review, penetration test on auth flows, and load test to confirm rate limits and p95 latency targets before production.

OWASP API Top 10
05

Deploy & monitor

Production deployment with uptime monitoring, error-rate alerts, latency dashboards (p95 and p99), and structured logging, issues surface before users report them.

p95 / p99 monitored
Our Stack

What we build APIs with.

The frameworks, tools, and services behind every API we ship.

Frameworks
FastAPI (Python)Node.js + ExpressNode.js + FastifyDjango REST FrameworkNestJSGo (net/http)
API Styles
REST / RESTfulGraphQL (Apollo)gRPC + ProtobufWebSocketWebhookstRPC
Auth & Security
OAuth 2.0JWTAuth0ClerkAPI key managementHMAC-SHA256
Databases
PostgreSQLMySQLMongoDBRedis (caching)SupabasePrisma ORM
Docs & Testing
OpenAPI 3.0 / SwaggerPostmanJestPytestk6 (load testing)Sentry
Infrastructure
AWS API GatewayAWS LambdaDockerKubernetesNginxCloudflare

Ways to work with us.

4 engagement structures that fit your project type and scale.

New API build

Full design-to-deployment API - spec, development, tests, docs, and production monitoring included.

Best for greenfield products

Third-party integration

Connect your system to Stripe, Twilio, HubSpot, WhatsApp, or any external API - with error handling, webhooks, and retry logic.

Best for adding integrations

Legacy API modernisation

Migrate SOAP to REST, add versioning, write missing documentation, and refactor brittle integrations without downtime.

Best for existing systems

API team extension

Embedded API developers working alongside your team on sprint-based delivery, for ongoing feature development and maintenance.

Best for growing products
Client Success

Growing businesses have
already made the move

End-to-End

From Idea to Revenue

5-Star

Client-Rated

Two Divisions

Software + Marketing

“Our business went from local to national thanks to Hoop. They completely transformed our e-commerce platform and helped us expand our customer base 5x. The results speak for themselves.”
Hamza Khan

Hamza Khan

Owner, Khayest

What's Included

Every API build comes complete.

No gaps between development and production readiness. Every API ships with the full set of surrounding infrastructure.

OpenAPI 3.0 spec
Full contract written before code ships.
OAuth 2.0 + JWT auth
Industry-standard authentication and authorisation.
Rate limiting (3 tiers)
Protects against abuse and DoS from launch.
Input validation
Schema-based validation on every endpoint.
Versioning strategy
URL versioning with documented deprecation policy.
Interactive docs
Swagger UI or Redoc, try endpoints in the browser.
Idempotency keys
Safe retry on write operations prevents duplicates.
Pagination & filtering
Cursor-based pagination for large result sets.
Unit & integration tests
Test coverage on every endpoint before deployment.
Production monitoring
Uptime, error rate, and p99 latency alerts live.

APIs for every sector.

Industries where we've designed and shipped APIs.

Fintech & Payments

Payment APIs, banking integrations, fraud detection.

Healthcare

HL7 FHIR APIs, patient data, telehealth integrations.

Ecommerce

Product, order, inventory, and fulfilment APIs.

Logistics

Tracking, fleet, shipment, and routing APIs.

SaaS Products

Multi-tenant APIs powering web, mobile, and partner access.

EdTech

LMS integrations, SCORM APIs, learner progress data.

HR & Workforce

Payroll APIs, HR system integrations, SSO connectors.

Developer Tools

Public APIs, CLI tooling, SDK generation, webhooks.

The Deep Dive

Understanding API development.

A direct guide to API types, security, versioning, and the design decisions that separate good APIs from ones developers avoid.

What is API development?

API development is the process of designing, building, documenting, securing, and maintaining an Application Programming Interface, the set of rules that define how two systems exchange data. APIs power every modern application: a mobile app calls an API to fetch user data; a web dashboard calls one to display orders; a partner integration calls one to sync inventory. Every consumer of an API is a client depending on a contract - and that contract is what API development defines and enforces.

A complete engagement covers six phases: requirements and consumer mapping, contract design (OpenAPI spec), implementation, security hardening, documentation, and production monitoring. Most teams do only the middle two phases and skip the rest - which is why APIs ship without rate limiting, break partners without warning, and fail silently in production.

REST vs GraphQL vs gRPC, which to choose

Choose REST for public APIs, mobile backends, and any API consumed by external developers. REST maps naturally to CRUD operations on resources, HTTP caching works with GET requests, and every developer already understands the pattern, it is the lowest adoption barrier.

Choose GraphQL when different client types need different data shapes from the same API. A mobile app needs five fields from a user object; a web dashboard needs twenty-two. REST returns all twenty-two in both cases (over-fetching) or needs a separate endpoint. GraphQL lets each client request exactly the fields it needs, at the cost of weaker HTTP caching and the need for query-complexity limits and DataLoader batching to avoid N+1 queries.

Choose gRPC for internal service-to-service communication in microservices. Protocol Buffers produce binary messages 5–10× smaller than equivalent JSON, and HTTP/2 multiplexing handles concurrent requests without head-of-line blocking. Not suitable for browser-facing APIs without a REST gateway.

Most production systems use all three: REST for public and partner APIs, GraphQL for the primary frontend API, and gRPC for internal microservice communication.

API versioning - 3 strategies and when to use each

URL versioning (/v1/users, /v2/users) is the most explicit and developer-friendly - the version is visible in every request log, URL, and error report. Breaking changes go into a new version; old versions stay live until sunset. This is the right default for most APIs, with a minimum 6-month deprecation notice.

Header versioning (API-Version: 2026-01-01) keeps URLs clean and uses date-based versions - Stripe's approach. More expressive for fast-evolving APIs, but harder to debug because the version is invisible in the URL.

GraphQL schema evolution avoids versions entirely by deprecating individual fields with an @deprecated directive rather than creating a new endpoint. Fields stay available until all clients stop using them, which requires usage analytics to verify.

Idempotency, why every write operation needs a key

An idempotent operation produces the same result when executed multiple times. GET requests are naturally idempotent. POST requests are not, calling POST /orders twice creates two orders.

Network failures cause clients to retry requests without knowing whether the first attempt succeeded. A retry on a non-idempotent endpoint creates a duplicate: two charges, two orders, two emails. The solution is an idempotency key, a unique identifier the client sends in a header (X-Idempotency-Key: ord_7f3k9x). The server stores the key and result; on a retry with the same key, it returns the stored result without re-executing. We implement this on all write endpoints using Redis with a 24-hour TTL.

API documentation, what good looks like

Good API documentation answers five questions without a support ticket: how to authenticate, what endpoints exist, what request body is required, what response to expect, and what to do when an error occurs. Interactive documentation - Swagger UI or Redoc rendered from an OpenAPI 3.0 spec, lets developers try endpoints directly in the browser with their actual API key. This is the minimum standard for any external or partner-facing API.

Complete docs include an authentication guide, code samples in JavaScript, Python, PHP, and cURL for every endpoint, an error-code reference, a changelog with breaking-change notices, and a migration guide per version. Teams that publish complete documentation receive far fewer integration support requests - the documentation is the support, not a substitute for it.

Related services.

Services that pair directly with API development.

SaaS Development

Multi-tenant SaaS platform with API backbone.

Explore

Mobile App Development

iOS and Android apps consuming REST or GraphQL APIs.

Explore

Web Application Development

Full-stack web apps built on the APIs we design.

Explore

Ecommerce Development

Shopify, WooCommerce, and headless commerce APIs.

Explore

Cloud Infrastructure

AWS API Gateway, Lambda, and containerised deployments.

UI/UX Design

Frontend interfaces built on top of the APIs we develop.

Explore

Software Testing

API contract testing, load testing, and security audits.

Custom Software

Bespoke builds, MVPs & enterprise systems.

Explore
More services in this area
AI DevelopmentVibe CodingCloud & DevOpsData & AnalyticsSecurity, QA & MaintenanceGame Development
FAQ

API Development Questions

The things clients ask us most before every API engagement.

REST uses separate endpoints per resource with fixed responses; GraphQL uses one endpoint where the client specifies exactly which fields to fetch. With REST, a mobile app and a web dashboard call the same endpoint and receive the same response even if the mobile app needs only a few of the returned fields. GraphQL lets each client request exactly what it needs, eliminating over-fetching. REST is easier to cache and has lower adoption friction for external developers; GraphQL is better when multiple client types with different data needs consume the same API.

Six layers secure every API we build: OAuth 2.0 and JWT authentication, tiered rate limiting, input validation on all parameters, HTTPS-only with TLS 1.3, CORS allowlisting, and HMAC-signed webhooks. OAuth 2.0 handles token issuance and scope; JWTs carry signed, stateless claims with short-lived access tokens and refresh rotation. Rate limiting runs at three tiers (60/hour unauthenticated, 5,000/hour authenticated, 15,000/hour premium), and input validation rejects malformed or malicious payloads at the boundary before they reach business logic.

API versioning lets you change an API without breaking existing integrations. Without it, a field rename or schema change breaks every partner and client app consuming the API. URL versioning (/v1/, /v2/) is the most explicit strategy - breaking changes go into a new version, old versions remain active until sunset. We enforce a minimum 6-month deprecation notice and add deprecation headers to old version responses so clients know when to migrate.

An idempotency key is a unique identifier the client sends with a write request so that retries do not create duplicates. If a POST request fails mid-flight (network timeout) and the client retries, the server might have already processed the first attempt. The idempotency key prevents a duplicate: the server stores the key and result for 24 hours, and retries with the same key return the stored result. We implement idempotency keys on all write endpoints (POST, PUT, DELETE) using Redis with a 24-hour TTL.

Yes. OpenAPI 3.0 is a machine-readable specification that describes every endpoint, request parameter, response schema, and authentication method in your API. It generates interactive documentation (Swagger UI, Redoc), client SDKs in multiple languages, mock servers for frontend teams to build against before the API ships, and contract tests that verify the implementation matches the spec. We write the OpenAPI spec before writing the implementation - the spec is the source of truth, not documentation added after the fact.

A focused REST API with 10–20 endpoints, authentication, rate limiting, and documentation takes 3–6 weeks. A comprehensive API backend for a SaaS product with 50–120 endpoints, multi-tenancy, webhook infrastructure, third-party integrations, and full test coverage takes 10–18 weeks. Timeline depends on the number of endpoints, integration complexity, and whether a database schema also needs designing. We give a phased timeline after a scoping session.

Yes. Third-party API integration is a core service we deliver alongside custom API development. For each integration we build the API call layer with error handling, webhook receivers for inbound events, retry logic with exponential backoff, and idempotency handling to prevent duplicate processing. Common integrations we've built include Stripe Billing, Stripe Connect, Twilio SMS/Voice, SendGrid, HubSpot CRM, WhatsApp Business API, Google Maps, Google Calendar, and Firebase.

Yes, always. Documentation is included in every API engagement, not a separate optional deliverable. We deliver an OpenAPI 3.0 spec, interactive Swagger UI or Redoc hosted on your domain, code samples in JavaScript, Python, PHP, and cURL for every endpoint, an authentication setup guide, and an error code reference. Documentation is maintained throughout development - every endpoint is documented as it ships, not in a final sprint after the build is complete.