API development that holds up
when things get real.
REST APIs, GraphQL, third-party integrations, and the API infrastructure that connects your systems. We've built the API layer for SaaS platforms, mobile apps, and enterprise software that run in production across the US, UK, and Australia.
Fixed-price, scoped to your build, no hourly billing surprises. Get your number →
8 years · 600+ projects · Fiverr Vetted Pro · US/UK/EU/AU clients
The API problems that bring people to us
If one of these is your week, here is what we do about it.
Someone exports a CSV every morning to move data between two systems.
We build the integration layer. A middleware service that keeps your systems in sync automatically, with retries and monitoring. We have wired together Xero, QuickBooks, Sage, Stripe, and Salesforce across live platforms.
The API works until traffic spikes, then it falls over and nobody knows why.
We harden and instrument it. Rate limiting, caching, connection pooling, and observability so failures are visible and traceable, not a 3am guessing game.
Your mobile and web clients each need slightly different data, and every screen means a new endpoint.
The right API shape for your clients. REST or GraphQL chosen for how your apps actually consume data, so the frontend team is not blocked waiting on backend tickets.
A third-party API has no real docs and the integration keeps breaking silently.
We assess it before we scope it. We check the API quality, contract the behaviour, and build defensive handling so their changes do not become your outages.
API work we actually do
APIs are the connective tissue of every software product we build. We treat them as first-class deliverables, not an afterthought.
REST API Design & Development
Well-designed REST APIs: consistent naming, proper HTTP semantics, pagination, filtering, versioning, and error responses that developers can actually use. OpenAPI 3.0 documentation generated from code, not maintained separately. We've built APIs for SaaS products, mobile apps, and third-party developer ecosystems.
GraphQL APIs
GraphQL for products where clients need flexible data fetching: mobile apps with limited bandwidth, dashboards with complex relational data, or developer APIs where over-fetching is a real problem. We've built both schema-first and code-first GraphQL APIs with subscription support for real-time features.
Third-Party Integrations
We've connected production systems to Xero, QuickBooks, Sage, Stripe, Salesforce, HubSpot, Zapier, SendGrid, Twilio, and dozens of industry-specific platforms. Integrations built to handle edge cases: API rate limits, webhook signature validation, retry logic, and the payload variations that only appear in production.
Webhooks & Event-Driven Systems
Outbound webhooks for your clients to subscribe to, inbound webhook receivers from third-party services, and event-driven architectures that decouple system components. Dead letter queues, retry logic, signature validation, and the monitoring that tells you when a webhook has been silently failing for three days.
API Gateway & Microservices
API gateway configuration, service mesh, rate limiting, authentication middleware, and the infrastructure layer between your clients and your backend services. When a monolith needs to split or when multiple services need a unified API surface, built when the scale justifies it, not as a default architecture.
Public Developer APIs
APIs designed for external developers, versioning strategy, backwards compatibility guarantees, SDK generation, API key management, rate limiting, and the documentation that developers actually read. When your API is a product, not just an implementation detail.
Built by AI-native engineers, so your API is ready for agents and LLM features
We design the API surface, auth, and event model so language-model features and AI agents can consume it safely later. It is how our own products, Tully AI and Mebag, were built.
Clear schemas, scoped tokens, and predictable errors so an AI agent can call your API without surprises.
Retrieval endpoints and event streams that feed a vector store without a nightly export job.
A managed layer in front of OpenAI, Anthropic, or Gemini with rate limits, caching, and fallbacks.
Shipped with prompt versioning, evals, and guardrails. See how we build AI →
How we design and build APIs
Design first: agree the contract before building
API design is a contract. We design the API surface, endpoints, request/response schemas, error codes, pagination, and get sign-off before writing implementation code. This means the frontend and mobile teams can work against a mock while the backend is built, and we don't end up with APIs that don't match what the clients need.
Security and auth: built in, not added later
Authentication strategy (JWT, API keys, OAuth2), authorization at the data level, rate limiting, and input validation designed before the first endpoint is written. Security added after the fact means retrofitting it into every endpoint. We don't do that.
Implementation with tests that catch regressions
API tests that run in CI and fail before a broken change reaches staging. Integration tests against real databases, not mocks that don't catch production issues. Contract tests for external integrations. We've been burned by test suites that give false confidence, we don't build those.
Documentation that developers actually use
OpenAPI 3.0 spec generated from code (not written separately and allowed to drift). Interactive documentation with real example requests. Authentication guides. Common error scenarios. The documentation your integration partners and internal teams will actually open when they're stuck.
Monitoring, alerting, and observability
Structured logging, response time monitoring, error rate alerting, and the dashboards that tell you when something is wrong before a client reports it. APIs in production fail in ways that staging never showed, we instrument for production reality.
Versioning and deprecation, planned in
APIs change, and consumers you do not control depend on them. We agree a versioning strategy, deprecation timelines, and changelog discipline up front, so a breaking change is a scheduled migration with notice, not an outage for an integration partner.
What we build APIs with
What API development costs
API work ranges widely depending on complexity. We quote a fixed price after scoping your project on a call, never an hourly rate.
A focused integration between two systems, connecting your app to Xero, building a Stripe billing integration, or implementing a webhook receiver from a third-party service. 2–6 weeks.
- Single integration
- Error handling + retry logic
- Testing + documentation
- Monitoring setup
A complete REST or GraphQL API backend for a web or mobile application, designed, documented, tested, and deployed. Includes auth, data model, and integration with 2–4 external services. 8–20 weeks.
- Full API design + implementation
- Auth + RBAC
- OpenAPI documentation
- 2–4 integrations
- CI/CD + monitoring
- API test suite
A public API as a product, developer documentation, SDK generation, versioning, partner onboarding, and the support infrastructure for external developers. Or a high-performance API handling millions of requests with real SLA requirements.
- Public developer API
- SDK generation
- Developer portal
- API gateway + rate limiting
APIs we've built in production
i-mve: Operations Platform API
A production REST API serving the i-mve web platform and mobile apps across 510 UK removals companies. Integrates with Xero, QuickBooks, and Sage for accounting. Stripe for payments. Custom webhook system for client notifications. Continuously maintained since the relationship began in 2022, the API has evolved through years of production use without breaking changes to existing clients.
View live platform →Read the case study →Smart Parking API
A real-time API serving the operator dashboard and driver mobile apps of a smart parking automation platform simultaneously. WebSocket connections for live bay status updates, REST endpoints for bookings and payment, and a hardware integration layer connecting to parking barrier systems. Performance requirements: sub-100ms response for availability checks at peak entry times.
Read the case study →COMPASS for Autism: Clinical Research API
A REST API for a clinical research platform at Ball State University. Role-based data access enforced at the API level, researchers, consultants, educators, and families all use the same API but see different data. Audit logging for all data access, data handling built to the client's own guidelines, and structured export formats for research analysis.
View live platform →Read the case study →What people ask about API development
Straight answers on API design, security, versioning, documentation, timelines, and ownership.
REST or GraphQL, which should I use?
REST for most APIs, it's simpler to implement, easier to cache, and better understood by the wider developer ecosystem. GraphQL when you have multiple clients (web, iOS, Android) with significantly different data requirements, or when you're building a developer-facing API where over-fetching and under-fetching are real problems. We'll recommend based on your actual use case, not on which is more interesting to build.
Can you integrate with our existing ERP or CRM?
Yes, integration is standard work for us. The quality of the integration depends on the quality of the third-party API. Xero and QuickBooks have well-documented REST APIs. Some legacy ERPs only have SOAP endpoints or CSV export. We assess integration complexity during scoping and price it accurately, not as a vague "TBD" line item.
How do you handle API versioning?
URL-based versioning (/api/v1/, /api/v2/) for public APIs where backwards compatibility guarantees matter. Header-based for internal APIs. We establish the versioning strategy at the start, not when a breaking change is already needed. i-mve's API has been in production since 2022 with active clients on multiple versions simultaneously, we know how to manage this.
How do you secure APIs?
JWT tokens for user sessions, API keys for service-to-service communication, OAuth 2.0 for third-party integrations, and RBAC enforced at the data layer, not just at the route level. Input validation, rate limiting, OWASP Top 10 compliance, and signature validation for webhooks. Security designed in from the start, reviewed before launch.
Do you provide API documentation?
Yes, OpenAPI 3.0 specification generated from the code, with interactive documentation (Swagger UI or Redoc). Authentication guides, example requests and responses, common error scenarios, and changelog. For public developer APIs we build a full developer portal. Documentation that's generated from code doesn't drift as the API evolves.
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What I love about Team7 is that they always say: No worries, we can find a solution. This is the mindset of builders, creators, people who do not have fear, the partner you need if you want to excel.
Working with Mo and his team over the past year has been nothing short of exceptional. I was admittedly sceptical about investing such a large amount, but results exceeded every expectation.
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Ready to build your API?
Tell us what you need to connect.
30 minutes. No slides. We'll look at your integration requirements and tell you honestly what it will take to build something that holds up in production.