TypeScript / JavaScript SDKs
Typed SDKs for Node.js, Bun, Deno, and browsers — with discriminated unions, ESM/CJS dual-bundle, tree-shakeable exports, and React/Vue/Next.js hooks where useful.
SDK Development
Multi-Language Client SDKs Developers Actually Love Importing
We design and build production-grade SDKs — typed client libraries for TypeScript, Python, Go, Java, Kotlin, Swift, C#, and Rust — generated from your OpenAPI or Protobuf contracts and hand-polished for ergonomics, with versioning, docs, semantic types, retries, and example apps your developer customers actually adopt.
TS · Python · Go · Java · .NET · Swift · Kotlin · Rust
8+Languages supported
OpenAPISpec-driven generation
SemVerPredictable versioning
100%Typed end-to-end
SDKs We Build
Production-grade client libraries across modern languages — generated from spec, hand-polished for ergonomics, and ready for your developer customers to npm-install on day one.
Python SDKs
Idiomatic Python clients with full Pydantic typing, async/await support, retries, pagination helpers, and PyPI publishing — for data science and backend teams alike.
Go SDKs
Idiomatic Go modules with proper error types, context-aware requests, structured logging hooks, and proto-buf gRPC stubs alongside REST clients.
Swift & Kotlin SDKs
Native mobile SDKs for iOS (Swift / SwiftPM) and Android (Kotlin / Maven Central) — with coroutines, structured concurrency, and platform-aware persistence.
Java, .NET, Rust SDKs
Enterprise SDKs for Java (Maven Central), C# / .NET (NuGet), and Rust (crates.io) — typed, ergonomic, and ready for your customers' build systems.
Docs & Example Apps
Hosted SDK docs, quickstarts in every language, end-to-end example apps, and migration guides — developer experience treated as the actual product.
Industries We Serve
SDKs that power developer adoption across fintech, healthcare, e-commerce, logistics, AI, IoT, and DevTools.
FinTech & BFSI
Healthcare
Retail & E-Commerce
Logistics
EdTech
IoT & DeepTech
DevTools
Real Estate
Languages & Tooling
Modern language ecosystems, spec-driven generation, and production-grade build tooling.
OpenAPI 3.1Spec
Protobuf / gRPCSpec
TypeScript 5+Language
Python 3.12+Language
Go 1.22+Language
Kotlin / SwiftMobile
Java 21 / .NET 8Enterprise
RustSystems
tsup / RollupTS Bundler
Poetry / HatchPython Build
GoReleaserGo Release
SemVerVersioning
Our SDK Development Process
A six-step rhythm engineered so SDKs ship with the polish that decides developer adoption in the first 10 minutes.
API Surface Audit
We audit your OpenAPI / Protobuf contracts, identify ergonomic gaps, suggest discriminated unions, idempotency surfaces, and pagination shapes that translate well to every target language.
DX Design
We design the developer experience for each language — method naming, error model, async patterns, retry policies, logging hooks — documented before any code is written.
Generation & Hand-Polish
Code-generated from spec where it works; hand-written where it matters (helpers, hooks, retries, pagination iterators). Every SDK passes the "would you publish this under your own name" test.
Tests & Mock Server
Unit tests, contract tests against a generated mock server, integration tests against your real sandbox, and snapshot tests on generated types to catch breaking spec changes.
Publish & Docs
Published to npm, PyPI, Maven Central, Go Modules, NuGet, crates.io, CocoaPods/SwiftPM — with hosted docs, quickstarts, and runnable examples per language.
Versioning & Care
SemVer releases driven from spec changes, deprecation cycles, migration guides, and a retainer for new languages or breaking-change communications.
Why Choose Hendoi for SDKs
Six commitments that decide whether your SDK becomes a developer-love story — or a stack-overflow question your support team dreads.
Developer Experience First
SDKs are judged in the first 10 minutes by your developer customers. We design for that moment — clear errors, helpful types, runnable quickstarts, and idiomatic patterns per language.
Spec-Driven, Not Hand-Hacked
Generated from OpenAPI 3.1 or Protobuf so SDKs stay in sync with your API forever — with hand-polished helpers added in named modules so codegen can re-run cleanly.
Multi-Language, Same Ergonomics
A TypeScript developer and a Python developer should feel equally at home. We harmonise patterns (auth, retries, pagination, error shapes) across every language we ship.
Predictable Versioning
Strict SemVer, deprecation cycles communicated in advance, migration guides published with every major bump, and CHANGELOG entries developers actually want to read.
Senior Library Authors
Our engineers have published and maintained popular open-source libraries. They know the difference between "code that compiles" and "code that developers love importing".
Transparent Engagement
Weekly demos with snippets in every target language, direct access to engineers, signed SOWs with documented ergonomic decisions, and predictable burn.
Engagement Models
Pick the shape that matches whether you need a first SDK, a harmonised family, or ongoing maintenance.
Single-Language SDK
Build the first official SDK in your most-requested language — usually TypeScript or Python — with full docs, quickstarts, and a published v1.0.0 ready for npm/PyPI.
- One language, deep polish
- Hosted docs + quickstarts
- Published v1.0.0
Multi-Language SDK Platform
Build a harmonised family of SDKs across 4-6 languages from one OpenAPI/Protobuf spec — with shared release pipelines, consistent ergonomics, and a developer portal.
- 4-6 languages harmonised
- Shared release pipelines
- Developer portal
SDK Maintenance Retainer
Predictable monthly retainer covering SDK regeneration from spec changes, language version upgrades, security patches, and new-language additions when demand justifies.
- Spec-driven re-generation
- Language version upgrades
- New languages on demand
Real-World Use Cases
Representative SDK programmes engineered for fintech, logistics, IoT, payments, healthcare, and AI platforms.
NBFC Lending API SDKs
TypeScript and Python SDKs for an NBFC's lending API — used by 30+ partner channel-sales platforms to apply, fetch status, and reconcile disbursals.
Logistics Platform SDKs
TypeScript, Python, PHP, and Ruby SDKs for a logistics platform — shipped to 200+ e-commerce sellers integrating shipment booking and tracking into their checkouts.
IoT Device SDKs
C, C++, and Rust SDKs for an industrial IoT platform — running on gateway devices with strict memory budgets, with OTA-friendly update channels.
Payments Aggregator SDKs
TypeScript, Java, .NET, and Go SDKs for a payment aggregator — abstracting Razorpay, PayU, and Stripe behind one ergonomic surface for partner merchants.
Healthcare API SDKs
TypeScript and Python SDKs for a healthcare API — typed FHIR resources, PII redaction helpers, and HIPAA-aware logging built into the client.
AI Platform SDKs
TypeScript, Python, and Go SDKs for an AI platform — streaming responses, retry-with-jitter, structured error types, and quickstart Colabs/Jupyter notebooks.
Frequently Asked Questions
Common questions API platforms and DevTools companies ask before committing to an SDK programme.
Should I build SDKs or just publish OpenAPI?
Publishing OpenAPI gives developers a reference. SDKs give them a 10-minute time-to-first-call. For any API where you have more than a handful of partner integrators, official SDKs in your top 2-3 languages pay for themselves in support cost saved.
Which languages should I ship SDKs in first?
For most APIs in 2026: TypeScript and Python cover 70%+ of developers. Add Go for cloud-native customers, Java/.NET for enterprise integrators, Swift/Kotlin if you have mobile customers, and Ruby/PHP if your audience requires.
Do you use OpenAPI Generator or write SDKs by hand?
Hybrid. Generated code for types, request/response models, and method skeletons; hand-written code for helpers (pagination iterators, retries, auth flows, websocket clients, hooks) — so codegen can be re-run without losing hand-polish.
How do you handle versioning and breaking changes?
Strict SemVer driven by spec diffs — non-breaking additions bump minor, breaking changes require a major bump with a published migration guide. Deprecations are communicated at least one major version in advance.
How is auth handled in SDKs?
OAuth 2.1 with PKCE for user flows, scoped API keys for service-to-service, and pluggable token providers so customers can integrate with their own secret stores (Vault, AWS Secrets Manager, etc.) — never hardcoding secrets in code.
Do you write SDK documentation?
Yes — hosted docs with reference (generated from OpenAPI), quickstarts in every language, runnable example apps in real repos, and a "first 10 minutes" page that every developer reads first.
How long does an SDK take to build?
A single high-polish language SDK typically takes 4-8 weeks. A harmonised family of 4-6 languages takes 12-20 weeks, including release pipelines and docs. We share milestones with snippets in every target language at each demo.
Can you maintain SDKs after launch?
Yes — under a maintenance retainer covering spec re-generation, language version upgrades, security patches, and adding new languages as customer demand justifies.