API development services from senior back-end teams on US hours
Senior back-end teams that design, build, secure and version REST, GraphQL and gRPC APIs, from public partner APIs to the internal services your product runs on.
By the Ryz Labs team · Updated October 2026
Ryz API development teams design and build REST, GraphQL and gRPC APIs, third-party integrations and the gateways, auth and documentation around them. You get senior back-end engineers from the top 1% of the people we interview, working on US business hours as a dedicated team that owns the API or as engineers who join your back-end team. The work starts with the contract, an OpenAPI or GraphQL schema reviewed with the consumers, and ends with versioned, monitored endpoints in production.
What we build
- Public and partner APIs: versioned REST APIs with OpenAPI 3.1 specs, API keys or OAuth 2.0 client credentials, rate limits and a developer portal your partners can self-serve from.
- Internal service APIs: gRPC or REST between microservices, with Protobuf contracts, deadlines, retries and circuit breakers so one slow service does not take down the others.
- GraphQL layers: a schema over existing services for web and mobile clients, with DataLoader batching, persisted queries, query cost limits and Apollo Federation when several teams own parts of the graph.
- Third-party integrations: connectors to Salesforce, Stripe, Plaid, NetSuite, Workday, HL7 FHIR endpoints and other systems, with idempotent retries and reconciliation jobs for when the other side fails.
- Webhooks and event APIs: signed webhook delivery with retries and replay, or event streams over Kafka, Amazon SNS/SQS or Azure Service Bus for consumers that need near-real-time data.
- API gateways and BFFs: Kong, AWS API Gateway or Azure API Management in front of your services, plus backend-for-frontend layers that shape data for each client.
- Legacy API wrappers: modern REST or GraphQL facades over SOAP services, mainframe transactions or databases, so new clients stop calling the old system directly.
- APIs for AI agents: well-described, permission-scoped endpoints that AI agents can call safely, often exposed through an MCP server.
How an engagement works
Talk. We map who consumes the API (your front end, mobile apps, partners, other services), the data it exposes, latency and volume expectations, and the security and compliance constraints.
Match. We propose engineers who have built in your language and framework, whether that is Node.js, Java with Spring Boot, Python with FastAPI, Go or .NET, and who have shipped the API style you need.
Join. The team works in your repos, CI and cloud accounts, joins your standups and demos working endpoints every week.
Grow. Add engineers as consumers multiply, or hand over a documented, tested API to your team when the build is done.
Week 1 typically covers the consumer list, a draft contract and decisions on auth, pagination, errors and versioning. By month 1, the first endpoints are running in a staging environment against the agreed contract, with contract tests in CI. By month 3, the usual picture is production traffic, dashboards for latency and error rates, generated SDKs or client libraries, and a deprecation policy for future versions.
The stack our teams work in
| Layer | Tools we use | Notes |
|---|
| Languages and frameworks | Node.js (NestJS, Fastify), Java (Spring Boot), Python (FastAPI, Django REST Framework), Go, .NET (ASP.NET Core) | We match your existing back-end stack. |
| API styles and contracts | OpenAPI 3.1, GraphQL (Apollo, Hot Chocolate), gRPC with Protobuf, AsyncAPI | Contract first, reviewed with consumers before code. |
| Gateways | Kong, AWS API Gateway, Azure API Management, Apigee | Rate limiting, auth and routing at the edge. |
| Auth | OAuth 2.0, OpenID Connect, Auth0, Okta, Amazon Cognito, Microsoft Entra ID | Scopes mapped to real permissions, not one admin token. |
| Data and messaging | Postgres, MySQL, DynamoDB, Redis, Kafka, SQS, Service Bus | Caching and async processing where latency needs it. |
| Testing | Pact, Schemathesis, Postman/Newman, k6, REST Assured | Contract, property-based and load tests in CI. |
| Docs and observability | Redocly, Swagger UI, OpenTelemetry, Datadog, Grafana | Docs generated from the spec; traces across services. |
How we keep APIs stable and secure
An API is a promise to its consumers. Most API failures come from breaking that promise by accident, or from security gaps that the OWASP API Security Top 10 has documented for years. Our teams guard against both:
- Breaking changes caught in CI. Tools like oasdiff or GraphQL Inspector compare each pull request against the published contract and fail the build on removed fields, changed types or new required parameters. Consumer-driven contract tests with Pact confirm real clients still work.
- Explicit versioning and deprecation. URL or header versioning chosen up front, Sunset and Deprecation headers, and a written window before old versions are turned off.
- Object-level authorization. Broken object level authorization (BOLA), where a user changes an ID and reads someone else's record, is the most common serious API flaw. Every handler checks ownership, and tests try other users' IDs on purpose.
- Input limits. Payload size caps, pagination limits, GraphQL depth and cost limits, and rate limits per client, so one consumer cannot exhaust the service.
- Idempotency. Idempotency keys on POST endpoints that create payments, orders or records, so client retries do not create duplicates.
- Consistent errors. RFC 9457 problem details or a documented GraphQL error shape, with no stack traces or internal identifiers leaking to clients.
- Load testing before launch. k6 or Gatling runs against staging at expected peak and above, with p95 and p99 latency targets agreed with consumers.
- Observability per consumer. Traces and metrics tagged by client, so when a partner reports errors, the team can see their exact requests.
Team shapes and cost
Typical Ryz cost is $7,000 to $15,000 per engineer per month. Mid-level engineers are $7,000 to $10,000, senior engineers are $10,000 to $15,000, and leads are $15,000 or more, quoted per team.
- Integration pair: 2 senior back-end engineers × $10,000 to $15,000 = $20,000 to $30,000 per month. Fits a set of third-party integrations or a focused internal API.
- API build team: a tech lead ($15,000+) plus 3 senior engineers ($30,000 to $45,000) = from $45,000 per month. Fits a new public or partner API with a gateway, auth and developer docs.
- Platform team: a tech lead, 4 senior back-end engineers and a senior DevOps engineer: $15,000+ plus 5 × $10,000 to $15,000 = from $65,000 per month. Fits a multi-team API platform with federation and shared tooling.
Every quote is scoped per team. You get a plan, a price and the names of the people before you start.
Dedicated team or staff augmentation?
A dedicated development team fits when the API is a defined deliverable, such as a partner API or an integration layer, and you want one team to own it from contract to production. If your back-end team has the design in hand and needs more senior hands, staff augmentation adds engineers who join your sprints. See our back-end developers and GraphQL developers pages for individual profiles. Either way, Ryz engineers work on your team, reporting to your leads.
When Ryz isn't the right fit
If you want a self-serve marketplace to hire an hourly freelancer for a single integration, a freelance platform will be quicker. If your team needs engineers on European or Asian hours, or follow-the-sun support for a global API, a global network fits better. If you want an off-the-shelf API management product rather than engineers, talk to a platform vendor.
Related
FAQ
Do you build REST or GraphQL APIs?
Both, plus gRPC for service-to-service traffic. REST with OpenAPI is the default for public and partner APIs. GraphQL fits when several clients need different shapes of the same data. We recommend a style after looking at your consumers, not before.
How much does API development cost?
Typical cost is $7,000 to $15,000 per engineer per month. Two senior engineers run $20,000 to $30,000 per month, and a lead plus three seniors starts at $45,000 per month. Total project cost is team size × duration × monthly rate.
How fast can the team start?
After the scoping call we propose a team with names. Most of the timeline depends on scope and on your onboarding, especially access to repos, cloud accounts and the systems the API connects to.
Can you work with our legacy systems?
Yes. Wrapping SOAP services, mainframe transactions or direct database access behind a modern API is common work for our teams, often as the first step of a legacy application modernization.
Who owns the code and the API contract?
You do. The team works in your repositories and cloud accounts, and specs, tests and docs live alongside the code.
Questions we didn't answer? Email info@ryzlabs.com.