Convert YAML to Kotlin online, free. YAML is an indentation-based superset of JSON favoured for human-edited config. Kotlin data classes model structured data with null-safety. YAML to Kotlin conversion parses your YAML against the YAML 1.2.2 grammar (https://yaml.org/spec/1.2.2/), builds an in-memory model of its keys, nested objects and arrays, then emits ready-to-use Kotlin types as data classes with nullable types following the Kotlin docs conventions. Processing runs in your browser in JavaScript with no upload or server round-trip — no size limit beyond your device's memory, so multi-megabyte documents convert in milliseconds and sensitive payloads never leave your machine. Typical uses include Android apps, Ktor services and kotlinx.serialization.
It maps the full structure of your YAML onto idiomatic Kotlin types, following the Kotlin docs conventions. 100% free, no registration, and complete privacy — everything runs locally in your browser, so your data never touches a server.
Paste YAML and generate Kotlin types from Kotlin immediately. Conversion runs client-side, so there is no upload wait and large documents stay fast.
Nested YAML objects, tables and arrays are mapped faithfully onto Kotlin, including nested types and optional fields.
Your YAML never leaves your device — everything is processed locally in JavaScript, with nothing logged or stored.
Unlimited conversions with no account, no quotas, and no watermark. Works on desktop and mobile.
A YAML document and its Kotlin equivalent:
YAML input:
label: web
replicas: 3
exposed: falseOutput:
@Serializable
data class Service(
val label: String,
val replicas: Int,
val exposed: Boolean,
)Paste your YAML into the editor and press "Convert to Kotlin". The tool parses it against the YAML 1.2.2 grammar, then generates Kotlin types following Kotlin docs conventions — instantly and entirely in your browser. You can validate or format the YAML first to be sure it is clean.
YAML anchors and aliases are expanded and comments are dropped before Kotlin is produced, and indentation defines the structure. Note that YAML 1.1 treats words like "yes" and "no" as booleans, so quote them if you want strings.
Optional or nullable members in the generated Kotlin are inferred from keys missing in some records of your YAML, following Kotlin docs. Include the optional fields in your sample so they are typed correctly.
YAML (YAML Ain't Markup Language) (YAML) — YAML is an indentation-based superset of JSON favoured for human-edited config. Kotlin data classes (Kotlin) — Kotlin data classes model structured data with null-safety. This converter maps the structure of your YAML onto Kotlin so you can use it for Android apps.
Yes. Invalid YAML is flagged with a clear error before anything is converted. Common YAML problems to check are spaces (never tabs) for indentation, consistent indent levels, and no duplicate keys. Starting from clean input keeps the generated Kotlin accurate.
Yes. The entire YAML-to-Kotlin conversion runs locally in your browser in JavaScript — your YAML is never uploaded, logged or stored. That matters when the data is something like Kubernetes & Docker Compose manifests, which should not leave your machine.
The generated Kotlin is ready for Android apps, Ktor services and kotlinx.serialization. Copy or download it and drop it straight into your codebase.
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