APIs engineered for integration and scale
US-based engineers building REST and GraphQL APIs — versioned, documented, tested, and safe for external consumption.
What this service delivers
APIs are the contract between your product and everything that integrates with it — partner systems, mobile apps, third-party developers, and your own front-ends. A well-engineered API is a strategic asset; a poorly designed one is a source of ongoing pain.
NextGen builds REST and GraphQL APIs with schema-first design, strict versioning, and consumer-driven contract testing. We build both internal APIs (for your own front-ends and services) and external APIs (for partners and third-party developers).
Every API we build is documented against a schema (OpenAPI or GraphQL SDL), instrumented for observability, and gated behind proper authentication and rate limiting.
Why choose NextGen Coding
Most API problems are design problems, not code problems. Endpoint sprawl, inconsistent naming, missing pagination, and unclear error semantics are baked in during design and are expensive to fix later. NextGen designs APIs before writing them.
Our engineers have shipped APIs consumed by hundreds of external developers, and understand what makes an API pleasant to build against versus quietly frustrating.
Built for teams that need to move
Platform companies
Products where the API is a first-class product surface with external consumers.
Integration-heavy products
Companies whose value proposition depends on smooth integration with third-party systems.
Mobile back-ends
Native app companies needing a well-designed back-end API for their mobile clients.
Public developer APIs
Companies launching a developer program with documentation, keys, and rate limits.
Internal service APIs
Teams splitting monoliths into services and needing consistent internal API standards.
Everything included in a NextGen build
API design
Resource modeling, endpoint design, and error semantics defined before any code is written.
OpenAPI or GraphQL schema
Machine-readable schema as the source of truth for the API.
Versioning strategy
URI, header, or field-level versioning with a defined deprecation policy.
Authentication
OAuth 2, API keys, or JWT sessions with scoped permissions.
Rate limiting
Per-consumer rate limits enforced at the edge with clear response headers.
Pagination and filtering
Consistent pagination, filtering, and sorting semantics across every list endpoint.
Webhooks
Signed webhooks with retry, replay, and consumer-facing debugging tools.
SDKs
Auto-generated or hand-crafted SDKs for JavaScript, Python, and other consumer languages.
API documentation
Reference docs, tutorials, and code samples generated from the schema.
Contract tests
Consumer-driven contract tests running in CI to catch breaking changes.
Observability
Per-endpoint latency, error, and volume metrics with alerts on regression.
Developer portal
Documentation, key management, and quickstart flows for external consumers.
How the engagement runs
Design
Resource modeling, endpoint design, and schema draft signed off by stakeholders.
Foundation
Auth, rate limiting, error semantics, and observability wired before feature endpoints.
Endpoint build
Endpoints built against schema with contract tests and staging deploys each week.
SDK and docs
SDK and documentation generated and validated as endpoints ship.
Load and abuse testing
k6 load tests plus abuse-pattern testing on rate limits and auth.
Developer feedback loop
Feedback from real consumers driving iteration and deprecation cycles.
Transparent, US-market pricing
API design engagement
Design-only engagement producing schema, spec, and implementation plan. Starting $18,000.
Full API build
Design plus implementation, SDK, and docs for a defined resource scope. Starting $60,000.
Developer portal
Portal, key management, and quickstart flow build on top of an existing API. Starting $28,000.
All pricing is transparent and US-market calibrated. We don't compete on the lowest upfront number — we compete on delivering outcomes that generate the highest return on investment.
Results our clients experience
External developer adoption
A platform client's API onboarded 340 external developers in the first 90 days after a portal and SDK relaunch.
Integration cycle cut in half
A B2B SaaS client's partner integration cycle dropped from 6 weeks to 3 weeks after we redesigned their public API.
P95 latency under 120ms
A financial-services API held P95 latency under 120ms across 12M+ daily requests on our stack.
Thought leadership & technical writing
REST vs GraphQL in 2026
When each pays back and how to choose based on your consumer profile.
Versioning without breaking
How to evolve an API for years without forcing consumer rewrites.
Webhooks that developers actually like
Signing, retry, replay, and observability for webhooks that work.
Objections, addressed
REST or GraphQL?+
Depends. REST is easier for external developers and simpler to cache. GraphQL wins when your consumers need to compose from many resources or when you have many client types with different data needs. We'll recommend based on your consumer profile.
Do we need a developer portal?+
If your API has external consumers, yes. If it's internal-only, a lightweight docs site is usually enough.
How do we prevent breaking changes?+
Versioning strategy, consumer-driven contract tests, and a clear deprecation policy. All three are non-negotiable for external APIs.
Frequently asked questions
Which languages do you build APIs in?+
Primarily Node.js/TypeScript, Python, and .NET, with Go for high-throughput or latency-sensitive APIs.
How do you handle authentication?+
OAuth 2 for external APIs, JWT sessions or opaque tokens for internal. Scopes and audience claims enforced everywhere.
Can you audit our existing API?+
Yes. A 1–2 week audit produces a design review, versioning assessment, and prioritized fix list.
Do you build SDKs?+
Yes. Auto-generated from schema where possible (OpenAPI Generator, GraphQL Code Generator), hand-crafted where ergonomics demand it.
Engineering discipline. US-based delivery.
NextGen Coding Company builds websites and software as measurable business assets, not decorative art. Our team combines rigorous engineering discipline with design and conversion strategy, and every deliverable is accountable to an outcome. Clients partner with a single US-based team that owns strategy, design, build, and post-launch iteration.
All work is performed by US-based engineers and designers. Our team's proximity to US business hours, cultural context, and buyer expectations produces web experiences that resonate with domestic audiences — a nuance offshore teams frequently miss. We serve clients from New York and across the country, from early-stage startups through Fortune 500 enterprises.
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