Real-Time Indexer Lag Monitor

WHAT IT DOES

The Real-Time Indexer Lag Monitor is an analytics tool that monitors and compares the block numbers of multiple RPC indexers against a reference block from your connected wallet provider. It continuously checks each indexer's latest block number, calculates the lag in blocks and approximate time delay, and visualizes the results. The tool provides real-time visibility into which indexers are keeping up with the chain and which are falling behind. This helps developers, dApp operators, and users identify reliable indexers for querying and ensuring data freshness.

HOW TO USE

Enter a list of RPC indexer URLs (one per line) into the input field. Optionally configure the check interval (default 10 seconds). Click "start monitoring" to begin real-time checks. The tool will fetch the reference block number from your connected wallet provider and compare each indexer's latest block against it. Results display in a detailed table showing each indexer's status, block number, lag in blocks, estimated lag time, and response time. A visual lag bar chart provides quick reference to identify the most lagging indexers. The monitoring continues at the configured interval until stopped.

TECHNICAL MECHANISM

The monitor operates by creating ethers JsonRpcProvider instances for each user-provided URL. It issues eth_blockNumber requests in parallel to all indexers and the reference provider. The reference block number is fetched from the wallet's connected provider using getBlock('latest'), providing a trusted baseline. For each indexer, the tool calculates lag as (referenceBlock - indexerBlock), estimates lag time by multiplying block difference by 12 seconds (standard Ethereum block time), and measures response time in milliseconds. The tool uses an exponential backoff strategy for errors and automatically handles provider failures. Results are rendered live with color-coded status indicators: green for synced (≤5 blocks behind), yellow for lagging (6-20 blocks behind), and red for severely lagging (>20 blocks behind or error). The monitoring loop runs at user-defined intervals, providing continuous visibility into indexer health.

WHAT IT CANNOT SEE

The tool cannot determine the exact lag of third-party indexers or subgraphs without their own APIs. It cannot measure RPC response times accurately without dedicated infrastructure, as network conditions and routing affect measurements. The tool cannot account for network propagation delays between different regions. It cannot detect reorgs that may affect block finality or identify whether an indexer has processed a specific transaction. The tool cannot monitor all available indexers simultaneously. It cannot determine the root cause of detected lag (network issues, provider throttling, infrastructure problems). The tool cannot predict future indexer performance or reliability.

PLEASE NOTE

This tool is designed for Ethereum Virtual Machine (EVM) compatible chains only. The estimated lag time (12 seconds per block) is approximate and varies by chain—users should adjust expectations based on the specific network's block time. The tool provides estimates only and should not be used as the sole basis for critical infrastructure decisions. Response times measured include both network latency and provider processing time. The tool requires a connected wallet provider to establish a reference baseline. Different wallet providers may report different latest block numbers due to their own indexing status.