Support matrix

Application SDKs (instrument services)

Language	Package / plugin	Import / symbol	Platforms
Python	`varianz`	`from varianz import Varianz`; `@vz.vpoint()`	CPython 3.10–3.15, PyPy 3.11 · macOS (x86_64, arm64), Linux glibc/musl (x86_64, aarch64)
TypeScript / JavaScript	`@varianz/node`	`createVPoints`, `@vpoint`, `VarianzContext`	Node.js 22+ · macOS (arm64, x64), Linux glibc/musl (x64, arm64)
Go	module `go.varianz.io/sdk`	`import "go.varianz.io/sdk/varianz"`; `varianz.VPoint(vz, name, fn)`	`CGO_ENABLED=1`, glibc-based Linux images or macOS
Java	Gradle plugin `io.varianz.sdk` (or Maven)	`io.varianz.annotations.vpoint.VPoint`	JVM 17+ · glibc and musl (Alpine) images
Kotlin	Gradle plugin `io.varianz.sdk.kotlin` (KSP)	`io.varianz.annotations.vpoint.VPoint`	Same as Java

Windows is not supported in v0.2.1 for any SDK. Varianz packages are published only under the exact coordinates above — if an import or package name differs from this table, it isn’t Varianz.

Test SDKs (drive tests)

Framework	Package	Notes
pytest	`varianz-pytest`	Auto-registers; `varianz` fixture
Vitest	`@varianz/vitest`	Fixture + custom matchers
Playwright	`@varianz/playwright`	Browser-driving; auto session header on `page`
JUnit 5	`io.varianz:varianz-junit`	`VarianzExtension` + `VarianzSession`
Kotest	`io.varianz:varianz-kotest`	Same lifecycle for Kotest specs
Go `testing`	`go.varianz.io/sdk/varianztest`	In the SDK module
Anything with lifecycle hooks	`@varianz/test` (Node)	Framework-agnostic helpers (`node:test`, etc.)

Test-side and service-side are independent: any test framework drives services in any supported language. See Test across services.

Feature availability differences

Capability	Python	TypeScript	Go	Java/Kotlin
`VARIANZ_ENABLED` runtime toggle	✅	✅	✅	✅ (interception also needs the agent attached)
Build-time schema tool	`varianz-scan`	`@varianz/scanner`	`varianz-gen`	annotation/KSP processor (automatic)
Schema resolution	type annotations, with runtime introspection as a fallback	scanner-derived from TS types, decorators as overrides	eager reflection, or codegen via `varianz-gen`	compile-time, from method signatures
Session carrier	`contextvars`	`AsyncLocalStorage`	`context.Context`	pull-based `@VarianzId` function

Languages without an SDK

Services in other languages (C#, PHP, Elixir, …) can’t host VPoints, but they participate in tests by forwarding the x-varianz-id header to downstream calls — see Test across services.

Getting started

Core concepts

Guides

SDK reference

Testing

Reference

Application SDKs (instrument services)

Test SDKs (drive tests)

Feature availability differences

Languages without an SDK

​Application SDKs (instrument services)

​Test SDKs (drive tests)

​Feature availability differences

​Languages without an SDK

Application SDKs (instrument services)

Test SDKs (drive tests)

Feature availability differences

Languages without an SDK