API & integrations

Connect your tools, expose your data, automate your flows. A well-designed API from day one avoids years of integration debt.

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Context

Your systems don't talk to each other. Or they don't do it well.

Teams re-enter the same data across tools because no connector exists — or the one you have isn't reliable.
Your ERP, CRM, billing stack, and line-of-business platform sit in silos. The only “single view” is a weekly Excel export.
Your product exposes an API built in a hurry — no versioning, no docs. Every consumer that depends on it makes the next change riskier.
You rely on a vendor to change a connector you don't own and can't see the code for.
You want to open your platform to partners or third parties — but the API was never meant to be exposed.

What we do

Design, integration, automation, modernization.

From API design to event-driven flows, one requirement: it has to last.

API design

You need to expose data or capabilities to other applications — yours or a third party's.

REST or GraphQL shaped around your consumers and constraints
A formal interface contract (OpenAPI / Swagger) before the first endpoint
Versioning, pagination, error handling — standards that limit long-term debt
Authentication and authorization (OAuth2, API keys, JWT)

Third-party system integration

Connect ERPs, CRMs, internal tools, and SaaS platforms without brittle one-off scripts.

Review of available APIs and their limits (rate limits, webhooks, formats)
Robust integration layer with error handling and retries
Bidirectional or one-way sync as needed
Automated integration tests to catch contract breaks early

Flow automation

Data moving between systems on its own — no manual steps, no silent failures.

Event orchestration across services (webhooks, queues, workers)
Asynchronous processing for high-volume flows
Flow monitoring with alerting on failures
Idempotency and reconciliation to protect data integrity

API modernization

Your current API is undocumented, unversioned, fragile, or built on a model that no longer holds.

Audit of the existing contract and map of consumers
Incremental refactoring without breaking live integrations
Migration toward REST or GraphQL from legacy stacks (SOAP, RPC)
Adding the versioning and documentation that's missing

API gateway & security

Centralize access, control traffic, and protect your endpoints.

Gateway rollout (rate limiting, routing, centralized auth)
API keys and per-consumer scopes
Request logging and inbound observability
Abuse protection (throttling, IP filtering)

Webhooks & events

React to system events in real time instead of polling in a loop.

Event model and payload design
Reliable inbound webhook handling (idempotency, retry)
Outbound webhooks to partners or external consumers
Message queues for critical paths (queues, dead-letter handling)

How we choose

REST or GraphQL — the right pick depends on who consumes the API.

We choose REST when…

Consumers are many and heterogeneous (mobile, web, external partners)
You want a cache-friendly API that's straightforward to document and test
You expose resources with clear CRUD-shaped operations
Maintainability matters more than maximal query flexibility

We choose GraphQL when…

Your front end needs nested data from several sources in one round trip
You want to limit over-fetching on mobile or low-bandwidth clients
Consumers need very different shapes over the same underlying data
You're building an open platform where clients define their own queries

Either way, we formalize the interface contract before writing code.

Methodology

Plan / Build / Run

API and integration work starts by mapping systems, flows, and critically who consumes each interface — locking the contract before endpoints ship avoids integration debt that grows with every new consumer.

Implementation, integration testing, documentation, and production monitoring align with the Build and Run phases described on our Methods page.

Explore our methodology

Technologies

Technology choices built to last.

Back end & API

NestJS
Node.js
TypeScript
REST
GraphQL

Specification

OpenAPI / Swagger
GraphQL SDL

Authentication

OAuth2
JWT
API Keys

Message queues

BullMQ
Redis
Webhooks

Database

PostgreSQL

Infrastructure

Docker
CI/CD

Your APIs and integration services can be hosted and monitored on Rehzzo Cloud — observability, alerting, and scalability included.

Use cases

Typical integration projects.

Product API for partners — Opening your platform to third parties with access control, quotas, and documentation.

ERP ↔ business tool connector — Bidirectional sync between your ERP and internal applications.

CRM ↔ web platform integration — Centralized customer and lead data without re-keying.

E-commerce flow automation — Orders, inventory, and fulfillment kept in sync between your storefront and logistics tools.

Legacy API overhaul — Gradual migration from a fragile or undocumented API to a clear, versioned contract.

SaaS integration foundation — Inbound and outbound webhooks, event handling, connectors to common tools (Stripe, Slack, HubSpot, etc.).

An integration problem or an API to build?

Describe your systems and current flows. We respond with an honest technical read and a realistic plan.

Describe your flows