API Development and Integration Services
We build the APIs your product runs on and connect it to the tools your business already uses: payments, CRMs, ERPs, accounting, messaging, maps and older in-house systems, plus MCP servers that let AI assistants work with your product safely.
- USD 25/hour offshore rate
- Working apps you can try
- 300+ projects shipped
What are API development and integration services?
API development and integration means building the interfaces that let software talk to other software, and wiring your systems together so data moves between them reliably. Lycore designs, builds, documents and monitors REST and GraphQL APIs, and connects your product to payment, CRM, ERP, accounting and messaging platforms.
Most businesses run on a handful of systems that do not talk to each other well. Orders are retyped into accounting, customer records drift apart between the CRM and the app, and a partner who wants your data gets a CSV by email. A well-built API and a few dependable integrations remove that manual work. The hard part is not the first successful call. It is handling the failed calls, the duplicate events, the expired tokens and the vendor who changes a field name, without anyone noticing. That is the part we focus on.
APIs and integrations we build
Six kinds of work make up most of our API projects. Many projects combine two or three of them.
REST and GraphQL APIs
Backends for your web and mobile apps, and public or partner APIs for your customers. REST for predictable resources and caching, GraphQL when clients need flexible queries across related data. Built in Node.js, Django REST Framework or FastAPI.
Payment integrations
Stripe Checkout, subscriptions, invoicing, customer billing portal and Stripe Connect for marketplaces. Webhooks are verified by signature and processed once, so a retried event never charges or credits twice.
Business system integrations
Two-way connections to CRMs such as Salesforce and HubSpot, ERPs, accounting platforms such as QuickBooks and Xero, email and SMS providers such as SendGrid and Twilio, and maps from Google Maps or Mapbox.
Webhooks and event-driven sync
Incoming and outgoing webhooks, message queues and scheduled sync jobs that keep records consistent across systems, with clear rules for which system owns each field.
Legacy system integration
Modern APIs in front of older databases, SOAP services, file drops and SFTP exports, so new apps can use old systems without a risky rewrite. We wrap first and replace later, one piece at a time.
MCP servers for AI assistants
Model Context Protocol servers that expose your product’s data and actions to Claude, ChatGPT and other assistants, with the same permissions, limits and logs as your own API.
Secure, documented API development and integration
An API is a public door into your data. These are the controls we build in so it stays safe, predictable and easy for other developers to use.
Security and access
- OAuth 2.0 and OpenID Connect. For user-facing access and third-party apps, with short-lived access tokens, refresh tokens and scopes that limit what each client can do.
- API keys done properly. Hashed at rest, scoped per client, shown once, easy to rotate and revoke.
- Rate limits and quotas. Per key and per user, with clear error responses, so one noisy client cannot slow everyone else down.
- Audit logs. Who called what, when and with which result, kept append-only for sensitive actions.
- Validation everywhere. Every request checked against a schema, and permissions enforced on the server for every record returned.
Documentation and reliability
- OpenAPI documentation. A spec kept in sync with the code, with interactive reference docs and examples partners can try.
- Versioning. A clear versioning scheme, deprecation notices and changelogs, so existing clients keep working when the API grows.
- Retries and idempotency. Exponential backoff for outgoing calls, idempotency keys for writes, and a dead-letter queue for events that still fail.
- Monitoring. Structured logs, error tracking and alerts on error rates, latency and failed syncs, so problems surface before customers report them.
- Testing. Unit and integration tests, contract tests against the OpenAPI spec, and vendor sandboxes for payment and messaging providers.
MCP servers: let AI assistants use your product
Your customers increasingly ask an AI assistant to do the work instead of opening your app. A Model Context Protocol (MCP) server gives assistants such as Claude and ChatGPT a defined set of tools: look up an order, create a ticket, pull a report. It is an API designed for AI clients, and it needs the same discipline as any other API.
- Small, well-described tools. Each tool does one clear job with typed inputs, so the assistant picks the right one and passes valid data.
- User-level permissions. The server acts as the signed-in user through OAuth, and sees only what that user can see in your app.
- Read first, write with care. Read-only tools ship first. Actions that send, pay or delete ask the user to confirm.
- Logged and limited. Every tool call is recorded and rate limited, like any other client of your API.
MCP work often sits alongside our wider AI development services, where we add assistants, AI search and agents to existing products.
Integration patterns in products we built
Lycore designed and built a growing set of working apps that are live and open to try. These are some of the integration and logging patterns inside them.
OnWay
Local delivery, Flutter
All Claude API calls are routed through a Supabase Edge Function, and only publishable keys ship in the app. Order state changes go through one idempotent function that appends to an event log, and dispatcher actions land in an append-only audit log.
Explore OnWayLyStream
Film streaming, web
Uploaded films go straight to Mux for encoding, rentals are paid through Stripe checkout in sandbox mode with cards saved on Stripe, and every AI call is logged with user, feature, model and tokens on an AI usage page.
Explore LyStreamStride
Project management, web
All AI runs on Stride’s servers, never from the browser. The workspace audit log records who did what and when, including every AI request and any request refused for going over the daily allowance.
Explore StrideLyCare
Care operations, web
Subscriptions go through Stripe’s secure checkout and billing page, AI uses Anthropic’s API with each request recorded along with the tools that ran, and a partner access log records every view and download.
Explore LyCareOur integration process
Five steps from scattered systems to monitored integrations you can rely on.
- 01
Map the systems
Which systems hold which data, who owns each field, and which vendor APIs, limits and sandboxes exist.
- 02
Design the contract
An OpenAPI spec or event schema agreed before code, with error handling and versioning decided up front.
- 03
Build against sandboxes
Integrations built and tested against vendor sandboxes and recorded responses, never live customer data.
- 04
Migrate and switch on
Backfill historic records, run old and new paths side by side where needed, then switch over.
- 05
Monitor and maintain
Alerts on failed syncs, vendor API changes tracked, and fixes shipped on a monthly retainer.
How much does API development and integration cost?
We price API work like our other projects: an offshore rate of USD 25 per hour, a fixed project price for a defined set of endpoints or integrations, or a monthly retainer for ongoing integration work and maintenance. As an indicative guide, most projects fall into one of these budget bands:
The biggest cost drivers are the quality of the vendor APIs, how much historic data needs to move, how many systems can change the same record, and how strict your audit and uptime needs are. Vendor subscription and usage fees are billed to you directly. You get a written estimate after a discovery call.
Building the app as well as the integrations? See our web app development services, our mobile app development service, or MVP development if you are starting from an idea.
Related reading
Guides from our blog on APIs, MCP and integration architecture.
Frequently asked questions
Should our API be REST or GraphQL?
REST is the right default for most public and partner APIs: it is simple to document with OpenAPI, easy to cache and familiar to every developer. GraphQL earns its place when one app needs flexible queries across many related objects, such as a dashboard pulling users, orders and invoices in one request. Some products use both: GraphQL for their own frontend and REST for partners. We recommend based on who will call the API.
Can you integrate with a legacy system that has no API?
Usually, yes. Depending on the system we read and write its database through a controlled service, wrap an existing SOAP or file-based interface, or automate scheduled exports and imports over SFTP. We put a modern, documented API in front of it so new apps never touch the old system directly. That lets you modernize in stages instead of betting everything on a single rewrite.
What happens when a third-party API changes or goes down?
We design for it. Outgoing calls retry with backoff, failed events go to a queue for replay, and each integration has alerts on error rates. Vendor deprecation notices are tracked so changes are made before the old version is switched off. On a monthly retainer we handle these updates for you, so a vendor change becomes a planned task instead of an outage.
Is it safe to connect our product to AI assistants through MCP?
It can be, with the right design. An MCP server should act as the signed-in user with OAuth, expose small and clearly described tools, start with read-only access and ask for confirmation before any action that sends, pays or deletes. Every call should be logged and rate limited like any other API client. We build MCP servers on top of the same permission checks your app already uses.
Need your systems to talk to each other?
Tell us which systems you run and where data gets stuck. We will tell you how we would connect them, what it would cost and how long it would take.
Talk to Lycore