Web3 Chucker: In-App OkHttp JSON-RPC Inspector & EVM Revert Decoder

#android #web3 #ethereum #solana

Building decentralized mobile applications (dApps) and crypto wallets on Android involves frequent JSON-RPC communications with Ethereum, Polygon, Arbitrum, or Solana RPC nodes (via Infura, Alchemy, or QuickNode).

Debugging failed transactions is notoriously difficult when raw JSON-RPC responses only return opaque 4-byte revert signatures (0x08c379a0) or generic execution reverted messages without clear parameter decoding.

web3-chucker extends OkHttp to inspect, parse, and decode Web3 JSON-RPC transactions and smart contract revert errors directly on-device.

🏗️ Architecture: JSON-RPC Parsing & Revert Lookup Engine

Method-Aware RPC Filtering: Automatically tags and filters JSON-RPC methods (eth_sendRawTransaction, eth_call, eth_estimateGas, personal_sign, solana_sendTransaction).
4-Byte Revert Decoder: Translates opaque error selectors (e.g. 0x4e487b71 -> Panic(uint256)) into human-readable contract revert reasons.
Latency & Gas Tracking: Measures round-trip RPC execution latency and flags gas estimation spikes.

🛠️ Step-by-Step Implementation Guide

1. Add Gradle Dependency

dependencies {
    // Debug builds: full JSON-RPC inspector & overlay UI
    debugImplementation("io.github.zakayothuku:web3-chucker:1.0.0")

    // Release builds: zero-overhead no-op artifact
    releaseImplementation("io.github.zakayothuku:web3-chucker-noop:1.0.0")
}

2. Configure Web3ChuckerInterceptor with OkHttp

val okHttpClient = OkHttpClient.Builder()
    .addInterceptor(
        Web3ChuckerInterceptor(
            context = applicationContext,
            maxContentLength = 250_000L,
            decodeReverts = true
        )
    )
    .build()

// Provide client to Web3j or custom RPC client
val web3j = Web3j.build(HttpService("https://mainnet.infura.io/v3/YOUR_KEY", okHttpClient))

3. Attach Floating Overlay

@Composable
fun WalletApp() {
    Box(modifier = Modifier.fillMaxSize()) {
        WalletNavHost()

        if (BuildConfig.DEBUG) {
            Web3ChuckerOverlay()
        }
    }
}

👉 GitHub Repository: github.com/zakayothuku/web3-chucker

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