Uptime Monitor for Contract-Dependent Frontends

WHAT IT DOES

Uptime Monitor for Contract-Dependent Frontends helps you verify that your critical smart contracts are available and returning expected responses. It performs automated checks on contract addresses you specify by calling view functions and verifying the results. Each check includes: verifying that bytecode exists at the address, calling a function you define (such as totalSupply(), balanceOf(), or any view function), and optionally validating that the return value matches an expected result. The tool displays each check with a clear up/down status, the response value, and the response time in milliseconds. It aggregates results into an uptime percentage, showing you how many of your contract dependencies are healthy at a glance. This is essential for frontend developers who need to ensure their dApp's contract dependencies are operational, for DevOps teams monitoring production deployments, or for anyone who wants to proactively detect contract issues before users are affected.

HOW TO USE

Connect your wallet to access the EVM network. Add one or more contract checks by entering a contract address, a description, a function signature to test, and optionally an expected return value. Click "Add Check" for each contract you want to monitor. Once you've added all your checks, click "Run Uptime Checks." The tool sequentially processes each check: it first verifies that bytecode exists at the address using eth_getCode, then encodes and executes an eth_call for the function signature you provided. If you specified an expected value, the tool compares the actual return value against it. Results are displayed as a summary dashboard showing total checks, number of up/down checks, and an overall uptime percentage. Each individual check shows its status, the returned value, the expected value if applicable, and the duration of the call. You can add as many checks as you need to monitor all your contract dependencies in one dashboard.

THE REAL MECHANISM

The tool uses direct RPC calls to the connected EVM node. For each check, it first calls eth_getCode to confirm the contract exists. If the contract is present, it builds an ethers.js Interface from the function signature and encodes the function call using encodeFunctionData. It then sends an eth_call to the node, which executes the function in the context of the current block without modifying state. If the call succeeds, the tool decodes the return value using decodeFunctionResult and compares it to the expected value if provided. The tool also tracks the time from request to response to measure latency. All checks run sequentially to avoid rate-limiting issues. The tool does not rely on external APIs or indexers—it uses only the same RPC your wallet uses, ensuring consistency with your application's actual view of the chain. The results are processed and displayed locally without any data leaving your browser.

WHAT IT CANNOT SEE

This tool cannot monitor frontend availability or off-chain services such as APIs, databases, or hosting providers. It cannot detect contract failures that do not revert with visible errors—for example, a contract that returns incorrect data without reverting will pass the check if no expected value is specified. It cannot distinguish between network congestion and contract issues; a slow response could be due to network latency rather than contract problems. The tool cannot monitor events, logs, or transaction history in real-time—it only checks current state via eth_call. It cannot detect if a contract has been paused or disabled unless that state is exposed through a view function that you include in your checks. It cannot detect upgradeable proxy implementations—it only checks the address you provide, not the implementation contract. The tool cannot verify that the contract's bytecode matches a specific version or source code—it only checks that bytecode exists.

PLEASE NOTE

Uptime Monitor for Contract-Dependent Frontends works exclusively with Ethereum Virtual Machine (EVM) compatible chains including Ethereum, Goerli, Sepolia, Polygon, BSC, Arbitrum, Optimism, Avalanche, and others. The tool requires the contract address to be valid on the selected network and for the RPC node to support eth_getCode and eth_call. It reads data only and does not send any transactions or modifications to the blockchain. All processing occurs client-side in your browser; no data is sent to any external server. The tool is free to use and does not require authentication. For best results, use view functions that are cheap to execute and return consistent values.