Custom API development
REST and GraphQL APIs with versioning, input validation, and OpenAPI docs your other developers can actually use.
API integration connects applications so they can exchange data and trigger actions without manual transfer. It is intended for teams that need a custom API, a third-party service connection, webhook processing, or a secure partner-facing interface.
What I build
What is included in API integration?
Third-party integrations
Stripe, HubSpot, Salesforce, QuickBooks, Twilio, and shipping/payment gateways connected to your app or database.
Webhooks & event sync
Inbound and outbound webhooks with idempotent handlers, signature verification, and automatic retries.
Auth, security & limits
OAuth 2.0, API keys, and JWT, plus rate limiting and scopes so a public API can't be abused.
Problems this solves
What problems can API integration solve?
- Two SaaS tools your business relies on that don't talk to each other.
- Staff exporting CSVs from one system and importing them into another every week.
- Partners asking for an API you don't have yet.
- An integration that fails silently because there are no retries or error alerts.
Example use cases
What does API integration look like in practice?
Stripe → database sync
Wired Stripe webhooks to keep an app's subscription state in sync automatically, with signature checks and idempotent handlers.
CRM automation
New leads captured on a site were pushed into HubSpot and announced in Slack — no manual entry, with retries on failure.
Partner API
Built a REST API with per-partner API keys, scoped access, and rate limiting so external partners could pull data safely.
Tech stack
What technologies power API integration?
Build
- Node.js
- Express
- GraphQL (Apollo)
- OpenAPI
Auth & safety
- OAuth 2.0
- API keys
- JWT
- Rate limiting (Redis)
Integrations
- Stripe
- HubSpot
- Salesforce
- Twilio
Events
- Webhooks
- Idempotency
- Retries
Process
How does API integration work?
01
Map the systems
Identify sources, destinations, and the data that must move.
02
Design the contract
Endpoints or events, auth, and error handling up front.
03
Build & harden
Implement with validation, retries, and rate limits.
04
Document & hand off
OpenAPI docs and monitoring so it stays reliable.
Most integrations I build run on Node.js, and they're part of my wider full stack development work. When an integration needs an LLM in the loop — classifying, extracting, or drafting — I combine it with AI application development.
Related services
Node.js Development Services
Node.js development provides the server-side APIs, real-time services, background jobs, and database access used by web and SaaS products. It is intended for teams building a new backend or improving an existing service that needs clearer architecture, authentication, queues, or live updates.
AI Application Development
AI application development adds model-based functions such as summarization, extraction, classification, retrieval, or assisted drafting to a software product. It is intended for teams with a defined workflow and data source that need an AI feature integrated with existing systems and measured for accuracy, cost, and failure cases.
Full-Stack Development Services
Full-stack development covers the frontend, backend, database, authentication, integrations, and deployment of a web product. It is intended for teams that want one developer to own these connected layers or complete an existing application end to end.
FAQ
Questions, answered
- Can you integrate two tools that don't natively connect?
- Usually yes. If both have APIs or webhooks (most SaaS tools do), I build the middle layer that syncs them — often Stripe, HubSpot, Salesforce, QuickBooks, or a custom internal system.
- REST or GraphQL for a new API?
- REST for simple, cacheable, public-facing APIs; GraphQL when clients need to fetch varied shapes of data or you're combining multiple back ends. I'll match it to how the API is consumed.
- How do you secure a public or partner API?
- OAuth 2.0 or scoped API keys for auth, JWT for sessions, and rate limiting to prevent abuse — plus input validation and signature verification on webhooks.
- Do you handle webhooks and failed-delivery retries?
- Yes. I build idempotent webhook handlers with signature verification and a retry/backoff strategy so a momentary outage doesn't lose data.
- Can you write into our existing CRM, like HubSpot or Salesforce?
- Yes — reading and writing records, syncing contacts and deals, and reacting to their webhooks are common parts of these integrations.
Let's build it together
Email me with what you need — I'll reply with a clear plan and next steps. Prefer chat? WhatsApp works too.