Custom API Development

OSM GROUP – Custom API Development

Our API Tech Stack

Custom API Development Tools & Technologies

We build high-performance, scalable APIs using the world's most trusted backend frameworks, protocols, databases, and cloud infrastructure — engineered to connect, power, and scale your product.

Node.js

Python

Java

.NET / C#

PHP

Express.js

FastAPI

REST API

GraphQL

gRPC

OpenAPI / Swagger

PostgreSQL

MongoDB

Redis

Kafka

Docker

AWS

What We Build

How We Power Your Product

We specialise in designing, building, and deploying custom APIs — from RESTful microservices and GraphQL layers to real-time WebSocket systems and third-party integrations that keep your product running at scale.

REST API Design & Development

We architect and build clean, versioned, fully documented RESTful APIs following OpenAPI standards — designed for performance, security, and seamless consumption by web, mobile, and third-party clients.

OpenAPI / Swagger documentation
Versioning & backward compatibility
JWT / OAuth2 authentication

GraphQL API Development

We design flexible GraphQL schemas and resolvers that let clients request exactly the data they need — reducing over-fetching, enabling real-time subscriptions, and accelerating frontend development velocity.

Schema design & type system
Queries, mutations & subscriptions
DataLoader & N+1 optimisation

Microservices Architecture

We decompose monoliths and design event-driven microservice systems with API gateways, service meshes, and message queues — giving your platform the modularity, fault tolerance, and scalability to grow without limits.

API gateway & service mesh
Event-driven with Kafka / RabbitMQ
Docker & Kubernetes deployment

Real-Time & WebSocket APIs

We build low-latency real-time systems using WebSockets, Server-Sent Events, and gRPC streaming — powering live dashboards, chat applications, collaborative tools, notifications, and multiplayer features.

WebSocket & SSE endpoints
gRPC bidirectional streaming
Redis Pub/Sub & presence systems

Third-Party API Integration

We integrate your product with payment gateways, CRMs, ERPs, social platforms, shipping providers, and any external API — building reliable connectors with retry logic, webhooks, and robust error handling.

Payment, CRM & ERP integrations
Webhook management & retry logic
OAuth2 social & SSO connectors

API Security & Performance

We harden every API with industry-standard security — rate limiting, input validation, encryption, and penetration testing — then optimise with caching, CDN layers, and load testing to guarantee sub-100ms responses at scale.

Rate limiting & DDoS protection
Redis caching & CDN integration
Load testing & monitoring

Ready to build your custom API? Start Your Project View Case Studies

Global API Excellence

Why We Are the First Choice For Custom API Development Worldwide

From startups to enterprise, OSM GROUP delivers battle-tested custom APIs trusted by products across 30+ countries. Reliability, speed, and security are our standards, not just promises.

APIs Delivered300+ Projects

Avg Uptime99.98% SLA

Avg Latency<80ms P99

Experience8+ Years

API-First, Documentation-First

We design your API contract before writing a single line of code — using OpenAPI specs to align stakeholders, unblock frontend teams, and ensure every endpoint is clear, consistent, and future-proof.

Built to Scale from Day One

From caching layers and connection pooling to horizontal scaling and CDN-backed responses — every API we build is architected to handle 10x your current load without a rewrite.

Transparent Delivery & Monitoring

You always see your API's health. We deliver live dashboards, detailed changelogs, and monthly performance reports — with full observability into latency, errors, and throughput at every stage.

Security-Certified Engineers

Our team holds AWS, Google Cloud, and OWASP-aligned certifications. Every API ships with penetration testing, HTTPS enforcement, and zero-trust authentication — not bolted on after the fact.

🔗 REST

◈ GraphQL

⚡ gRPC

🔄 WebSocket

Requests

4.8M

↑22%

P99 Lat.

74ms

↓11%

Uptime

99.9%

↑0.1%

Err Rate

0.02%

↓40%

Daily API Requests Last 7 days

MonTueWedThuFriSatSun

API Type Mix

REST 39%

GraphQL 24%

gRPC 20%

WS 17%

Auth

96%

Cache

82%

Cover

91%

New endpoint deployed

+18 routes live ✅

What Sets Our API Development Apart on the Global Stage

Four core commitments that products from 30+ countries rely on

Performance-Obsessed

Every API we build targets sub-100ms P99 latency. We profile, cache, and optimise relentlessly — so your endpoints stay fast as your user base scales from hundreds to millions.

Protocol Agnostic

REST, GraphQL, gRPC, WebSocket — we select and combine the right protocol for each use case, building a unified API layer that's fast, flexible, and easy for any client to consume.

Developer Experience First

Clean SDKs, interactive Swagger docs, sandbox environments, and versioned changelogs — we build APIs that developers love to integrate, reducing onboarding time from weeks to hours.

Always Secure by Default

Security isn't a checkbox — it's baked into every layer. OAuth2, rate limiting, input sanitisation, encryption at rest and in transit, and regular security audits ship with every project we deliver.