A coroutine-first Socket.IO client for Kotlin Multiplatform — Android, iOS and JVM — with an in-house Engine.IO v4 / Socket.IO v5 implementation and no third-party protocol or logging dependencies.

implementation("io.github.adventures92:sockit:0.0.2")

val client = SocketClient.connect(
    "https://example.com",
    socketOptions {
        transports(Transports.WEBSOCKET)
        auth { put("token", jwt) }
    },
)
val socket = client.namespace()

launch { socket.connectionState.collect(::render) }
launch { socket.events("quote").collect(::handleQuote) }

socket.openAwait()
socket.emit(Subscribe(buildJsonObject { put("pair", "BTC-INR") }))

📖 Documentation · API reference

Transports are polling and WebSocket with automatic upgrade, multiplexed per origin, with exponential-backoff reconnect, binary attachments, server-initiated acks and a sealed error model. Verified against the official socket.io-protocol test vectors and a live socket.io 4.5.4 – 4.8.1 server matrix on every pull request.

Requires JDK 17+ and the Android SDK. Everything runs through the Gradle wrapper.

# Quality gates — run before considering any :socketio change done
./gradlew :socketio:apiCheck spotlessCheck :socketio:detekt

# Unit + protocol tests (no server needed)
./gradlew :socketio:jvmTest --tests "dev.adven.sockit.protocol.*"

# Full JVM suite — spawns the bundled Node echo server itself
cd socketio/src/jvmTest/resources && npm ci && cd -
./gradlew :socketio:jvmTest

# Platform smoke (simulator / device required)
./gradlew :socketio:iosSimulatorArm64Test
./gradlew :socketio:connectedAndroidDeviceTest

# API reference
./gradlew :socketio:dokkaGeneratePublicationHtml   # → socketio/build/dokka/html/

Formatting is spotless + ktlint (./gradlew spotlessApply); static analysis is detekt at maxIssues: 0. Any change to the public api/ package needs a matching ./gradlew :socketio:apiDump.

./gradlew :androidApp:assembleDebug     # Android
# iOS: open iosApp/ in Xcode and run

Full wire/FSM logs are compiled out of release builds. For local library development:

./scripts/toggle-socketio-internal-logging.sh on   # or off / status / (no arg = flip)
./gradlew :androidApp:installDebug                 # rebuild — the flag is compile-time

The script writes gradle/socketio-dev.local.properties (gitignored); every Gradle build reads it automatically. One-off override: ./gradlew -Psocketio.internalLogging=false …. Logs land in Logcat on Android, the Xcode console on iOS, and stdout under jvmTest.

Consumer-facing logging is separate and sanitized — Logger.essential { … } via socketOptions { logger = … }, single tag SocketIO, no URLs, tokens or payloads. See logging.

Issues and pull requests are welcome. See CONTRIBUTING.md for the workflow and the gates a change has to pass.

Apache 2.0 — see acknowledgements for prior art this client was studied against.