YAML to Kotlin Converter

YAML is a indentation-based, human-friendly configuration format — widely used for Kubernetes manifests, Docker Compose, CI/CD pipelines, Helm charts, application config. Converting it to strongly-typed Kotlin structures eliminates runtime surprises and speeds up development. This tool does it in one click, entirely in your browser.

Generate Kotlin data classes with null safety, default values, and Moshi/Gson serialization annotations.

How to use this converter

1. Paste your YAML into the left editor panel
2. Click Generate
3. Copy the generated Kotlin code from the right panel

No account. No upload. No tracking. Runs entirely in your browser.

Example Kotlin output

import com.google.gson.annotations.SerializedName
 
data class Address(
    @SerializedName("city") val city: String,
    @SerializedName("zip") val zip: String
)
 
data class User(
    @SerializedName("id") val id: Long,
    @SerializedName("name") val name: String,
    @SerializedName("email") val email: String? = null,
    @SerializedName("address") val address: Address
)

The problem with manual YAML-to-Kotlin mapping

Kotlin is a concise, null-safe JVM language language — typed data models are central to how it works. Yet copying fields from YAML payloads into Kotlin data class definitions introduces subtle errors:

• Mistyped field names cause silent deserialization failures
• Missing optional fields trigger runtime panics or null errors
• Schema drift between API and model goes undetected until production

Kotlin data classes automatically generate equals(), hashCode(), copy(), and toString() — perfect for immutable data transfer objects.

This converter eliminates the manual step entirely.

Kotlin and YAML: what you need to know

Kotlin is a concise, null-safe JVM language language, official Android language and popular for Spring Boot on JVM. It uses data class based with null-safety built in for structured data — making it a natural fit for YAML-driven applications.

What the converter generates

Output uses Kotlin data class syntax with nullable types (String?) for optional fields. Constructor parameters include @SerializedName or @Json annotations for Gson and Moshi compatibility.

A common gotcha

Kotlin distinguishes between nullable (String?) and non-nullable (String) types — this converter infers nullability from your input data.

YAML input characteristics

YAML is a superset of JSON and supports multi-line strings, block scalars, and complex nested structures. YAML is the de-facto standard for cloud-native configuration — Kubernetes, GitHub Actions, and Ansible all use YAML.

When should I use this converter?

Use this for Android or Kotlin Multiplatform projects where you need idiomatic data classes from API response payloads without manually mapping each field.

Common use cases

• Generating data classes for Retrofit + Gson/Moshi in Android projects
• Creating Kotlin models for Ktor server-side API response handling
• Producing serializable models for Kotlin Multiplatform shared modules
• Validating YAML contract compatibility with Kotlin type definitions
• Generating Kotlin models from Android development API responses
• Creating typed DTOs for Ktor APIs
• Rapid prototyping with real YAML payloads
• Keeping Kotlin structs in sync when YAML schemas evolve
• Onboarding new team members by auto-generating the data layer

Frequently asked questions

What version of Kotlin does the output target?

The converter targets modern Kotlin conventions — Kotlin data class with nullable (?) fields and default values. If you need output for an older version, the generated code can typically be adapted with minor changes.

Is my YAML data sent to a server?

No. All conversion runs locally in your browser using client-side JavaScript. Your YAML data never leaves your machine.

What YAML inputs does this converter accept?

Paste any valid YAML — including Kubernetes manifests, Docker Compose, CI/CD pipelines, Helm charts, application config. The converter infers types and generates a matching Kotlin model.

What serialization library does the generated Kotlin code assume?

The generated code is compatible with the standard Kotlin serialization ecosystem — Kotlin data class with nullable (?) fields and default values. No unusual dependencies required.

Related tools on LangStop

• YAML Formatter & Validator
• YAML to Python Converter
• YAML to Go Converter
• YAML to Java Converter
• YAML to JSON Schema

If you work frequently with YAML and Kotlin, bookmark this page to skip the manual model-writing step entirely.