API Platform and Microservices Engineering

API and Microservices Development Services

Build Reliable Contracts Between Products, Teams, and Systems

Devlyn designs and builds APIs, microservices, webhooks, integration layers, and event-driven systems for product teams that need dependable backend contracts. We help CTOs and engineering leaders turn fragile endpoints, tightly coupled services, undocumented integrations, and migration pressure into a clear API platform with service boundaries, OpenAPI or AsyncAPI documentation, authentication, authorization, rate limits, idempotency, retries, versioning, observability, contract tests, deployment discipline, and maintainable developer experience.

Scope our API platform See API scope

Contract-first APIs

OpenAPI, AsyncAPI, tests

Service boundaries

Domains, data, ownership

Production reliability

Retries, logs, runbooks

API projects fail when teams treat endpoints as tickets instead of contracts

A reliable API is a product boundary. Frontend teams, mobile apps, partners, internal services, data jobs, and customer integrations all depend on that boundary being clear, versioned, secure, observable, and stable under change.

What breaks

Endpoints are added quickly but there is no shared contract, schema discipline, naming model, error format, pagination pattern, or ownership map.

Microservices are split by technology convenience instead of business domains, which creates distributed coupling, duplicated data rules, and release coordination pain.

Authentication exists but authorization rules, object-level access checks, tenant boundaries, service scopes, and audit trails are inconsistent across endpoints.

Webhooks, background jobs, and event streams fail silently because retries, dead-letter handling, idempotency, ordering assumptions, and replay strategy were not designed.

Consumers lose trust because versioning, deprecation, changelogs, sandbox behavior, documentation, and backwards compatibility are handled only after something breaks.

How Devlyn reduces risk

We define API contracts before implementation: resources, operations, schemas, errors, auth scopes, idempotency rules, rate limits, versioning, events, and consumer expectations.

We map service boundaries to product domains, data ownership, transaction needs, latency constraints, deployment ownership, operational load, and team responsibilities.

We build security into every contract with authentication, authorization, input validation, sensitive data handling, audit events, throttling, and OWASP API risk review.

We treat asynchronous behavior as first-class product infrastructure with event contracts, webhook delivery logs, retries, duplicate handling, observability, and failure recovery.

We leave your team with source code, API specifications, architecture decisions, tests, deployment paths, runbooks, documentation, and a migration or growth roadmap.

What we deliver in API and microservices development

The service covers the technical and operational work needed to build APIs that other teams can safely depend on.

01

API discovery and contract design

Define consumers, resources, schemas, operations, auth scopes, error models, pagination, filtering, versioning, rate limits, idempotency, webhooks, and acceptance criteria before build work begins.

02

REST, GraphQL, and gRPC development

Build the right interface for the use case: resource-oriented REST, flexible GraphQL, high-performance gRPC, internal APIs, partner APIs, and product platform APIs.

03

Microservices architecture and extraction

Design service boundaries, decomposition sequence, data ownership, inter-service communication, deployment model, migration strategy, and fallback paths for monolith-to-service transitions.

04

Webhooks and event-driven systems

Build webhook delivery, event schemas, AsyncAPI documentation, queues, streams, retries, dead-letter handling, duplicate detection, replay tooling, and consumer-facing event logs.

05

API security and reliability engineering

Implement authentication, authorization, access checks, input validation, secrets handling, throttling, abuse controls, observability, contract tests, performance checks, and incident runbooks.

06

Developer experience and handover

Ship OpenAPI or AsyncAPI specs, Postman collections, SDK guidance, sample payloads, changelogs, integration notes, environment setup, test fixtures, and maintenance documentation.

API and microservices capabilities we can build

Every engagement is scoped around the business workflow, consumer expectations, and operational risk behind the API surface.

Public and partner APIs

Public and partner APIs

Expose product capabilities to customers, partners, marketplaces, and internal app teams with clear auth, scopes, versioning, documentation, usage limits, and support workflows.

Internal platform APIs

Internal platform APIs

Create stable backend contracts for frontend, mobile, admin, reporting, automation, AI workflows, and service-to-service communication across a product platform.

Integration middleware

Integration middleware

Build integration layers for CRMs, ERPs, payment providers, data vendors, support tools, communication platforms, warehouses, and legacy systems without leaking vendor complexity into the product core.

Microservice decomposition

Microservice decomposition

Extract bounded services from a monolith in phases, with compatibility layers, data migration planning, strangler patterns, release gates, monitoring, and rollback paths.

Webhook infrastructure

Webhook infrastructure

Design outbound and inbound webhook systems with signing, retries, delivery attempts, event catalogs, replay controls, duplicate handling, and integration troubleshooting tools.

API modernization and rescue

API modernization and rescue

Audit undocumented endpoints, inconsistent authentication, slow services, brittle integrations, schema drift, missing tests, and poor observability, then stabilize the highest-risk paths first.

Contract layers that make APIs maintainable

OpenAPI defines HTTP API descriptions so consumers can understand a service without reading source code. We use that contract-first principle as an operating model, not just as documentation after the fact.

Resource and operation model

Define nouns, verbs, paths, request bodies, response bodies, status codes, filters, sorting, pagination, bulk operations, and error cases in a consistent language.

Schema and validation rules

Create schemas that describe field names, types, required values, nullable behavior, enums, nested objects, file handling, validation errors, and compatibility constraints.

Authentication and authorization

Design API keys, OAuth flows, JWT claims, service credentials, scopes, tenant context, object-level checks, admin paths, and audit behavior around real access risks.

Reliability behavior

Specify idempotency keys, retry rules, timeout expectations, rate limits, concurrency behavior, conflict handling, eventual consistency, and safe duplicate handling.

Events and webhooks

Document event names, payloads, delivery rules, signing, ordering expectations, replay behavior, subscriber setup, failure states, and troubleshooting surfaces.

Developer experience

Publish examples, environments, changelogs, SDK notes, Postman collections, sandbox data, migration guidance, and support notes so consumers can integrate without guessing.

Security and reliability are designed into the API surface

The OWASP API Security Top 10 highlights risks such as broken object-level authorization, broken authentication, unrestricted resource consumption, improper inventory management, and unsafe consumption of APIs. We use those risk patterns while designing, building, testing, and reviewing the API layer.

Object-level and function-level authorization

Check whether the caller is allowed to access the specific object, tenant, action, role, and workflow, not just whether the request is authenticated.

Resource consumption controls

Add rate limits, quotas, payload limits, timeout policies, pagination limits, request validation, and abuse signals around expensive operations.

API inventory and exposure review

Maintain endpoint inventories, ownership, auth requirements, data classification, deprecation status, environment exposure, and documentation status.

Safe third-party API consumption

Wrap vendor APIs with timeouts, retries, circuit breakers, schema validation, error mapping, secrets hygiene, failure queues, and monitoring.

Request-level observability

Capture traces, logs, metrics, correlation IDs, error classes, latency, dependency calls, tenant or account context, and integration-specific failure details.

Contract and regression testing

Use contract tests, schema checks, integration tests, security test cases, backwards compatibility checks, and release gates before consumers are affected.

Microservices only help when the boundaries are worth owning

A microservice is not automatically better than a monolith. It creates value when a domain needs independent ownership, release control, scaling behavior, failure isolation, or integration surface. We help decide what should become a service, what should stay together, and what should be extracted later.

Domain and data ownership

Domain and data ownership

Map services around business capabilities, source-of-truth data, invariants, ownership, and the workflows that should change together.

Communication patterns

Communication patterns

Choose REST, gRPC, queues, streams, events, or direct database access alternatives based on latency, consistency, failure modes, and team ownership.

Transaction and consistency design

Transaction and consistency design

Handle cross-service workflows with sagas, outbox patterns, idempotency, eventual consistency, reconciliation jobs, and compensating actions where required.

Deployment and release ownership

Deployment and release ownership

Set service pipelines, environments, version gates, migration order, feature flags, compatibility checks, rollback paths, and operational responsibility.

Data migration and compatibility

Data migration and compatibility

Plan database splits, schema changes, backfills, read models, dual writes only where justified, consumer compatibility, and safe cutover windows.

Service operations

Service operations

Add service-level objectives, alerts, dashboards, logs, traces, runbooks, dependency maps, incident ownership, and capacity planning for each extracted service.

Technology stack and API standards

We choose tools based on consumer needs, latency, data consistency, team ownership, cloud environment, integration complexity, security requirements, and maintainability.

REST

REST

GraphQL

GraphQL

gRPC

gRPC

WebSockets

WebSockets

Server-Sent Events

Webhooks

Webhooks

Event streams

Internal APIs

Public APIs

Partner APIs

Integration gateways

Laravel

Laravel

Node.js

Node.js

NestJS

NestJS

Express

Express

Python

Python

FastAPI

FastAPI

Django

Django

Go

Go

PHP

PHP

Serverless functions

Background workers

Queues

Queues

Scheduled jobs

OpenAPI

OpenAPI

AsyncAPI

AsyncAPI

JSON Schema

JSON Schema

Protocol Buffers

Postman

Postman

Swagger tooling

Swagger tooling

Generated clients

Examples

Changelogs

Developer onboarding material

Kafka

Kafka

RabbitMQ

RabbitMQ

AWS SQS

AWS SQS

AWS SNS

AWS SNS

Google Pub/Sub

Google Pub/Sub

Azure Service Bus

Azure Service Bus

Redis streams

Redis streams

Event outbox patterns

Dead-letter queues

Replay tooling

OAuth

OAuth

OpenID Connect

OpenID Connect

API keys

JWT

JWT

mTLS

RBAC

RBAC

ABAC

Tenant context

Secrets management

Secrets management

API gateways

API gateways

WAF rules

WAF rules

Audit logs

Docker

Docker

Kubernetes

Kubernetes

Terraform

Terraform

GitHub Actions

GitHub Actions

AWS

AWS

Azure

Azure

Google Cloud

Google Cloud

OpenTelemetry

OpenTelemetry

Datadog

Datadog

Sentry

Sentry

Grafana

Grafana

Prometheus

Prometheus

Uptime monitoring

How the API and microservices engagement runs

We make the hidden decisions visible early so engineering, product, security, and integration stakeholders know what will be built and how it will be operated.

We review current systems, frontend and mobile needs, partner requirements, internal service dependencies, legacy constraints, data flows, pain points, and launch goals.
Map consumers and workflows
We define API style, resource model, schemas, events, auth, authorization, service boundaries, ownership, versioning, error handling, and operational requirements.
Design contracts and boundaries
We implement working endpoints, services, integrations, queues, tests, docs, and observability in slices that consumers can review against real acceptance criteria.
Build vertical API slices
We test auth rules, object access, schema compatibility, idempotency, retries, rate limits, webhook behavior, performance, dependency failures, and rollback paths.
Validate security and reliability
We set up environments, CI/CD, gateway rules, migration steps, changelogs, consumer communication, dashboards, alerts, incident paths, and handover documentation.
Prepare release and migration
We support new endpoints, deprecations, integration updates, service extraction, observability tuning, performance work, security review, and developer experience improvements.
Operate and evolve the platform

API and microservices engagement models

Scoped options for buyers comparing API development companies, microservices development partners, integration teams, and internal platform engineering capacity.

Assess

API Discovery and Contract Audit

Best when an existing API layer is undocumented, inconsistent, risky, or hard for consumers to use

Scoped

after discovery

Endpoint inventory

Security and contract review

Service boundary map

Modernization roadmap

Talk to Sales
Most Popular

Build

Production API or Microservice Build

Best for new REST, GraphQL, gRPC, webhook, integration, or microservice delivery

Scoped

after discovery

Contract-first design

Implementation and tests

Security and observability

Docs and handover

Talk to Sales

Scale

API Platform and Integration Support

Best for live API platforms that need ongoing delivery, reliability, and developer experience improvements

Scoped

after discovery

New integrations

Platform operations

Versioning and deprecations

Performance and reliability

Talk to Sales

Who this service is for

API and microservices development is the right service when backend contracts affect revenue, roadmap speed, product reliability, partner integrations, or operational trust.

01

CTOs building a product platform

You need internal APIs, external APIs, service boundaries, identity, eventing, observability, and documentation that product teams can build on without constant rework.

02

SaaS teams expanding integrations

You need partner APIs, webhooks, OAuth apps, usage limits, event logs, integration settings, and developer documentation that help customers connect your product safely.

03

Enterprises modernizing legacy systems

You need to expose legacy capabilities through stable APIs, decompose high-risk areas, create compatibility layers, and move toward services without disrupting active workflows.

04

Engineering leaders fixing API debt

You inherited undocumented endpoints, fragile service calls, missing tests, inconsistent auth, weak monitoring, or integration failures and need a phased path to stability.

Build the API layer your product and partners can trust

Share your API goals, current backend, integration pain, service boundaries, security requirements, and delivery constraints. We will help you scope the right contract, build, migration, or platform support path.

Scope our API platform View SaaS development

hello@devlyn.ai

Contract-first design

Service boundaries

Security review

Observability and handover

Frequently Asked Questions

Direct answers for buyers comparing API development services, microservices development, REST API development, GraphQL API development, webhook infrastructure, integration modernization, and API platform engineering.

They can include API discovery, contract design, REST, GraphQL, gRPC, webhook systems, event-driven services, microservice extraction, integration middleware, API security, observability, contract testing, documentation, deployment, and support.

We choose based on consumers, data shape, latency, tooling, governance, and operational needs. REST fits many public and partner APIs, GraphQL fits client-driven data needs, and gRPC fits service-to-service workflows where performance and typed contracts matter.

Yes. We can create or improve OpenAPI specifications for HTTP APIs so consumers understand endpoints, schemas, parameters, responses, auth requirements, examples, and error behavior without reading source code.

Yes. We can document and build event-driven systems with AsyncAPI, event schemas, channels, messages, queues, streams, webhooks, retries, dead-letter handling, replay controls, and subscriber guidance.

Yes. We can build public or partner APIs with authentication, authorization scopes, usage limits, versioning, documentation, sandbox guidance, webhook events, changelogs, and support workflows.

Yes. We can audit current endpoints, contracts, auth rules, data exposure, error handling, performance, documentation, tests, integration failures, and ownership, then plan a phased modernization path.

We avoid a big rewrite by identifying bounded domains, data ownership, consumer dependencies, release risks, and migration seams. Then we extract services in phases with compatibility layers, monitoring, and rollback paths.

We design authentication, authorization, object-level access checks, tenant boundaries, scopes, input validation, secrets handling, rate limits, audit logs, sensitive data rules, and OWASP API risk review into the API contract and implementation.

Yes. We can build outbound and inbound webhook systems with event catalogs, signed payloads, retries, delivery logs, duplicate handling, replay tools, failure states, and troubleshooting views.

We design idempotency for state-changing operations where needed. That can include idempotency keys, request hashing, unique operation IDs, safe retry behavior, conflict responses, and storage rules for completed operations.

We define versioning, compatibility rules, deprecation paths, changelogs, schema evolution, consumer communication, and release gates before breaking changes are introduced.

Yes. We can integrate CRMs, ERPs, payment systems, identity providers, communication platforms, data providers, analytics tools, legacy systems, and AI services through clean adapters and monitored workflows.

Useful inputs include current API docs, repository access, architecture notes, consumer list, integration requirements, authentication model, data model, system diagrams, cloud setup, known incidents, and product roadmap priorities.

Handover can include source code, OpenAPI or AsyncAPI specs, architecture decisions, endpoint inventory, auth model, tests, deployment process, observability dashboards, runbooks, integration notes, and roadmap recommendations.