API Development & Integration
We design, build, and operate the APIs that connect your systems to customers, partners, and each other. Every contract is specified before a line of code ships, and every integration is built to survive a bad day on the other end of the wire.
Does a partner's webhook going down for an hour actually get noticed before reconciliation breaks?
Endpoints get built ahead of agreement, error responses differ from service to service, and a "quick" third-party integration turns into a support burden that outlives whoever wired it up. The cost shows up everywhere else — support tickets, failed payments, engineers re-deriving behavior from source code instead of reading a spec.
What we target
These are the outcomes we scope every engagement against — targets we commit to in writing, not results we're claiming to have already delivered for you.
Overview
Most enterprises do not have an API problem so much as a coordination problem. Endpoints get built ahead of agreement, error responses differ from service to service, a partner's webhook goes down for an hour and nobody notices until reconciliation breaks, and a "quick" third-party integration turns into a support burden that outlives the person who wired it up. The API layer is where internal teams, partners, and customers actually meet your systems, and when it is inconsistent or undocumented, the cost shows up everywhere else — in support tickets, in failed payments, in engineers re-deriving behavior from source code instead of reading a spec.
This service is for engineering leaders who need APIs and integrations that outlast the person who built them: teams shipping a public or partner-facing API for the first time, teams consolidating a sprawl of ad hoc internal services behind a proper gateway, and teams that need a third-party system — an ERP, a CRM, a payment provider, a messaging platform — connected in a way that survives outages, retries safely, and reconciles cleanly.
QTK-Cloud works contract-first. We model resources and write the OpenAPI 3.1 or GraphQL SDL definition before implementation starts, agree error shapes and pagination conventions up front, and treat the contract as the source of truth that both producer and consumer code are tested against. Authentication, rate limiting, and versioning are decided as part of design, not bolted on when the first outage happens. Webhooks and event delivery are built with signing, replay protection, and dead-letter handling from day one, because "the partner didn't get our webhook" is a solved problem, not an acceptable incident.
What changes for the client is predictability. New consumers integrate from a published spec instead of a Slack thread. Breaking changes follow a deprecation policy instead of arriving as a surprise. Support incidents come with structured logs and a trace ID instead of a guess. And when a new API needs to ship, your team has a gateway, an identity model, and a testing pattern already in place to build against.
What's included
REST & GraphQL API design
Contract-first resource modeling in OpenAPI 3.1 or GraphQL SDL, with consistent RFC 9457 problem+json error shapes, pagination, filtering, and sorting conventions applied across every endpoint.
Third-party integrations
Connections to ERP, CRM, payment, and messaging platforms, including sandbox credential handling, field mapping, and reconciliation jobs that catch drift between systems before it reaches a customer.
API gateway management
Routing, request/response transformation, response caching, and WAF rules at the edge, so individual services stay simple and cross-cutting concerns live in one place.
Real-time webhooks
Signed payloads, replay protection, and at-least-once delivery with consumer-side idempotency guidance, backed by dead-letter queues and exponential backoff retries for failed deliveries.
Authentication & authorization
OAuth 2.1 and OIDC for user-delegated access, JWT validation and scopes for service calls, mTLS for server-to-server traffic, and API keys scoped to their actual risk level.
Rate limiting & observability
Per-key and per-tenant quota tiers, structured request logs, distributed tracing, and per-endpoint SLOs so you know an integration is degrading before a partner tells you.
Who this is for
You're shipping a public or partner-facing API for the first time
External consumers need a stable, documented contract, not an internal endpoint that happened to become public.
You're consolidating a sprawl of ad hoc internal services behind a proper gateway
Internal APIs have grown inconsistently, with different auth, error shapes, and versioning per team.
A third-party system needs to be connected reliably
An ERP, CRM, payment provider, or messaging platform needs to be integrated in a way that survives outages and retries safely.
Support incidents come with a guess instead of a trace ID
When an integration breaks, nobody can tell quickly whether the fault is on your side or the partner's.
How we work
- 1
Discovery
We map existing consumers, upstream systems, and current pain points. You receive a short integration inventory and a list of open decisions to resolve before design starts.
- 2
Design
Resources, error shapes, versioning policy, and auth model are agreed and written down. You receive a reviewable OpenAPI 3.1 or GraphQL SDL contract plus a mock server to build against immediately.
- 3
Build
We implement the API or integration against the agreed contract, wire up the gateway, and set up signed webhooks with retry and dead-letter handling. You receive working code in your repository, not a black box.
- 4
Validate
Contract tests run producer against consumer expectations, load tests confirm the rate-limit and latency targets hold, and webhook delivery is fault-injected to prove retries work. You receive a test report and a Postman or Bruno collection.
- 5
Handover & run
We walk your team through the gateway config, dashboards, and runbooks. You receive an operational runbook, generated SDKs where useful, and an optional retainer for ongoing changes and incident support.
Not sure this is the right fit yet?
A scoping call costs nothing and tells you exactly where your pipeline stands — no commitment either way.
Tech stack
We pick tools to match the integration, not the other way around — the stack below covers the majority of engagements.
Tools by layer
| Layer | Tools we use |
|---|---|
| API design & contracts | OpenAPI 3.1, GraphQL SDL, Swagger UI |
| Runtime & frameworks | Node.js, FastAPI, Go |
| Gateway & edge | Kong, Envoy, NGINX |
| Messaging & events | Kafka, RabbitMQ, Redis |
| Identity & access | Keycloak, OAuth 2.1, OIDC |
| Testing & tooling | Postman, Pact, OpenTelemetry |
How we handle reliability
| Concern | How we handle it |
|---|---|
| Auth | OAuth 2.1 / OIDC for delegated user access, mTLS for server-to-server calls, scoped JWTs validated at the gateway, API keys reserved for low-risk read paths. |
| Versioning | Additive-first changes with a published deprecation window and sunset headers; breaking changes ship on a new version path, never in place. |
| Rate limits | Per-key and per-tenant quota tiers enforced at the gateway, with burst allowance and explicit 429 responses carrying Retry-After. |
| Retries | Idempotency keys on unsafe methods, exponential backoff with jitter on the client side, dead-letter queues for webhook deliveries that exhaust retries. |
| Observability | Structured JSON logs, distributed request tracing, and per-endpoint SLOs tracked against latency and error-rate targets. |
Deliverables & outcomes
- Reviewable OpenAPI 3.1 or GraphQL SDL contract, versioned in your repository
- Working API or integration code, delivered into your codebase, not a locked-down third-party platform
- Gateway configuration for routing, transformation, caching, and WAF rules
- Signed webhook implementation with retry, dead-letter, and replay-protection logic
- Generated client SDKs and a docs portal for consumers
- Postman or Bruno collection and a mock server for parallel client development
- Contract tests (Pact) wired into CI for both producer and consumer
- Operational runbook covering incident response, rotation of credentials, and on-call escalation
Engagement models
How the work runs, independent of what it costs — pick the model, then see what it looks like at each pricing tier below.
Fixed-scope API or integration build
A single, well-specified API or third-party integration designed contract-first and delivered as a defined project.
Best for: A specific integration or API with a clear scope and end date.
Ongoing retainer
We continue operating the gateway, handling incidents under SLA, and building new endpoints or integrations as your needs grow.
Best for: Teams running multiple APIs or integrations who need continuous ownership.
Embedded alongside your team
An engineer works inside your team on contract design, gateway configuration, and integration code as part of your existing sprint process.
Best for: Teams building internal API platform capability who want the pattern to transfer as it's built.
Pricing tiers
| Plan | What this service looks like |
|---|---|
| Starter — $299/mo | A single well-specified API or one third-party integration, basic rate limiting, and email support for changes. |
| Professional — $1,499/mo | Multiple APIs behind a managed gateway, webhook infrastructure with retries and dead-letter handling, and priority support for incidents. |
| Enterprise — Custom | Full API platform ownership: gateway, identity, event streaming, SDK generation, contract testing pipelines, and a dedicated account manager. |
Scoping calls are free. Before any work starts, we confirm the exact scope, timeline, and price in writing so there are no surprises once the engagement begins.
Frequently asked questions
How long does an API or integration project take?
A single well-scoped API or integration typically takes two to six weeks from discovery to handover, depending on the number of endpoints, upstream systems involved, and how much of the identity and gateway layer already exists. Multi-API platforms and complex ERP or payment integrations run longer and are scoped individually.
Who owns the code and the API contract afterward?
You do. All code, contracts, and configuration are delivered into your repositories under your ownership. We do not retain rights to anything we build for you, and there is no vendor lock-in on the API layer itself.
What access do you need to get started?
Read access to relevant repositories, sandbox credentials for any third-party systems being integrated, and a point of contact who can answer questions about existing consumers. We scope exact access needs during discovery and request nothing beyond what the engagement requires.
How does handover work?
Handover includes a walkthrough of the gateway configuration, dashboards, and runbooks with your team, plus written documentation covering incident response and routine operational tasks. If you choose a retainer, we stay involved for ongoing changes and incident support after handover.
What happens if there's an incident after launch?
Every API we build ships with structured logs, request tracing, and per-endpoint SLOs, so incidents are diagnosable from the first alert rather than reconstructed after the fact. Retainer clients get defined response times; fixed-scope clients receive the runbook needed for their own team to respond.
Can we keep our existing tooling instead of adopting yours?
Yes. We design around the gateway, identity provider, and messaging systems you already run wherever they are fit for purpose, and only recommend a change when the existing tooling cannot meet the reliability or security requirements the integration needs.
Ready to talk about your project?
Tell us where things stand today and where you need them to be — scoping calls are free.
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