API & Middleware Architecture
CRM & Data / API & Middleware Architecture

Connect every system without building a maintenance nightmare

Custom API design, middleware architecture, and integration governance for businesses connecting CRM to 3 or more external systems. Built to scale, documented to maintain, governed to last.

3+

Systems connected avg

REST & SOAP

Full API expertise

99.9%

Uptime by design

Full docs

Every integration documented

Business challenges

Why API & Middleware Architecture projects fail

01

Point-to-point integrations that break everything

Every new system is connected directly to every other system. Five platforms means twenty point-to-point connections. Change one and three others break. The architecture becomes unmaintainable within 2 years.

02

No API documentation exists

The integrations work — most of the time. But nobody knows how. The developer who built them has left. Any change carries significant risk because nobody understands what anything does.

03

No error handling or retry logic

APIs fail silently. Data stops syncing. Nobody knows for hours or days. Customer records are out of date across the business while the team works from stale information.

04

Integration governance does not exist

Different teams add new integrations using different standards, different authentication methods, and different error handling patterns. The landscape grows unmanageable within 2 years of the first integration.

What is included

Everything in this service

API Design

Design RESTful APIs with clear endpoint naming conventions, authentication standards (OAuth 2.0, API keys, JWT), versioning strategy, rate limiting, and documentation format. Every API designed to be maintained by a team, not just one developer who happens to know it.

REST API designOAuth 2.0 / JWT authAPI versioningRate limiting & throttling

Deliverables

API specification (OpenAPI 3.0)
Authentication design document
Versioning & deprecation policy
Rate limit configuration

How it works

Our delivery process

01

Integration audit

Map every current and planned integration — what connects to what, using what protocol, how reliably, and whether it is documented.

02

Architecture design

Design the middleware strategy and governance framework that eliminates point-to-point complexity.

03

API standardisation

Define and document the API standards every integration must follow going forward.

04

Build & test

Build integrations to the agreed standard with full error handling, retry logic, and monitoring hooks.

05

Governance handover

Deliver the integration registry, governance framework, documentation, and run a knowledge transfer session.

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Success stories

Client results

All case studies

Celumai replaced our 14 point-to-point integrations with a clean middleware hub. We went from spending 40% of engineering time on integration maintenance to under 5%. The governance framework means every new integration now follows a consistent standard from day one.

C

CTO

B2B SaaS Platform

The API documentation they delivered is the first time our entire integration landscape has been fully documented. Two months after handover it has already prevented two incidents that would have been significant without it.

H

Head of Technology

Healthcare Network

Case study Healthcare

1,200 hrs saved/yr

Multi-city Healthcare Chain

Gen AI Automation for Multi-city Healthcare Provider

Read case study →
Case study Retail & E-commerce

360° customer view

National E-commerce Brand

Data Architecture Redesign for E-commerce Retailer

Read case study →

Platforms we use for this service

MuleSoft Azure Integration Services AWS API Gateway Dell Boomi Zapier Enterprise Custom REST & SOAP
API Architecture Self-Assessment

Free resource

API Architecture Self-Assessment — get it free

Score your current integration architecture across design quality, documentation, governance, and resilience — and identify your highest-risk connections.

Excel Worksheet · Free

FAQ

Your API & Middleware Architecture questions, answered

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Architect your integration layer

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98% on-time delivery across 40+ projects

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