This is a Kotlin Multiplatform library that provides PHP serialization format support for kotlinx.serialization.

Add the following dependency to your build.gradle.kts or build.gradle file:

dependencies {
    implementation("com.jsoizo:kotlinx-serialization-php:0.2.1")
}

encoding

@Serializable
data class User(val id: Int, val name: String)

val user = User(id = 100, name = "John")

val encoded = PHP.encodeToString(user)
// "O:4:\"User\":2:{s:2:\"id\";i:100;s:4:\"name\";s:4:\"John\";}"

decoding

val encoded = "O:4:\"User\":2:{s:2:\"id\";i:100;s:4:\"name\";s:4:\"John\";}"

val decodedUser = PHP.decodeFromString<User>(encoded)
// User(id=100, name="John")

To customize the behavior, build a configured instance with the PHP {} builder:

val php = PHP {
    // Skip fields in the PHP data that the Kotlin class does not declare
    // (default: false, unknown fields raise SerializationException)
    ignoreUnknownKeys = true
    // Register contextual/custom serializers
    serializersModule = SerializersModule { /* ... */ }
}

val decoded = php.decodeFromString<User>(encoded)

PHP serializes protected properties as "\0*\0name" and private ones as "\0ClassName\0name"; these are automatically matched to the Kotlin property by their bare name when decoding.

To see more usage and examples, please refer to the kotlinx.serialization documentation

Kotlin types that can be serialized to and deserialized from PHP serialization format.

Float.NaN and infinities are mapped to PHP's NAN / INF / -INF in both directions. Map keys must be Int, Long, String or Char because PHP array keys can only be integers or strings; other key types fail with SerializationException.

• JVM
• Android
• Native (iOS, macOS, Linux, Windows)
• JS
• WebAssembly (wasm-js, wasm-wasi)

• Sealed classes are encode-only. The output contains no type discriminator, so the original subclass cannot be recovered when decoding — neither by this library nor by PHP.
• Class names are not validated or mapped. Encoding uses the Kotlin class's simple name (PSR-1 validated); decoding ignores the class name in the input entirely. There is no mapping for namespaced PHP class names such as App\Models\User.
• PHP references and custom serializable objects are not supported. Payloads containing R: / r: (references) or C: (classes implementing Serializable) cannot be decoded.
• List decoding ignores array keys. Elements are read in their serialized order, so sparse arrays (e.g. a:2:{i:5;...;i:9;...;}) lose their indices. Decode such data into a Map instead.
• Integer-like string keys. PHP converts array keys like "123" to integers when serializing; such keys cannot be decoded into a Map<String, V> (use Map<Long, V> when keys may be numeric).