Casper FFG Checker

WHAT IT DOES

Casper FFG Checker gives you complete visibility into the live consensus state of any EVM-based Casper FFG (Friendly Finality Gadget) consensus contract. It reads and displays the current consensus contract state including epoch information tracking current, previous, justified, and finalized epochs, the complete validator set with individual weights, checkpoint states showing the current checkpoint root, justified checkpoints that have received supermajority support, finalized checkpoints that are irrevocably confirmed, pending checkpoints awaiting voting, validator voting records showing how each validator voted on checkpoints, FFG vote counts aggregating support for each checkpoint, slashable offenses that could trigger penalties, slashing conditions defining penalty parameters, source checkpoint and target checkpoint for the current voting period, validator rewards earned from participation, epoch proposers for each epoch, block heights at which checkpoints are created, deposit contract state tracking validator deposits, withdrawal credentials for staked funds, individual validator balances, active validator count, total staked ETH across all validators, finality status indicating whether the current epoch is finalized, checkpoint root hashes for verification, validator activation queue for new entrants, validator exit queue for exiting validators, and validator status flags indicating active, pending, or slashed states. All data is organized in a clean dashboard with real-time checkpoint tracking, giving developers and protocol researchers deep insight into Casper FFG consensus execution and finality.

HOW TO USE

Connect your wallet to the tool and select the network where your Casper FFG consensus contract is deployed. Enter the consensus contract address in the input field and click "Check FFG State". The tool immediately queries the contract using batched multicall to retrieve all consensus state variables in a single consistent snapshot. Results are displayed in organized cards showing the overall system state, checkpoint status with justified and finalized epochs, validator statistics including active count and total staked ETH, and pending operations like activation and exit queues. The tool refreshes data on demand by clicking the Check FFG State button again. The tool works with any EVM Casper FFG contract that implements standard view functions for epochs, checkpoints, validators, and finality tracking.

THE MECHANISM

Casper FFG Checker uses a batched multicall pattern to fetch all consensus state variables in a single RPC request, ensuring that every piece of displayed data comes from the exact same block height. This prevents inconsistencies that would occur if separate calls were made — for example, justified epoch and finalized epoch might change between calls if a new checkpoint is finalized mid-query. The tool constructs a single multicall transaction containing all required view functions including currentEpoch, justifiedEpoch, finalizedEpoch, checkpointRoot, activeValidatorCount, and totalStakedETH, sends it to the provider, and decodes the aggregated response. If the multicall fails due to provider limits or timeouts, the tool automatically falls back to individual calls, then reconciles results by block number, discarding any data that comes from a different height than the majority. The tool also implements automatic retry with exponential backoff for each call attempt, because public RPC endpoints frequently timeout or reject large batch requests. All validator weights and staked amounts are formatted to 18 decimals by default using ethers.js utilities, and finality status is computed by checking whether the current epoch matches the finalized epoch. The tool also tracks pending checkpoints by reading the pendingCheckpoints view function, providing insight into checkpoint accumulation.

WHAT IT CANNOT SEE

Casper FFG Checker cannot verify actual validator performance or detect if validators are voting honestly or following the Casper FFG protocol, as those require analyzing actual vote patterns. The tool cannot prove that validators are not double-voting or surrounding votes without running a consensus client and validating each vote individually. It cannot detect off-chain validator coordination or collusion among validators, as that is not recorded on-chain. The tool cannot verify the cryptographic validity of validator signatures without running a consensus client and validating each signature individually. It cannot predict future finality or guarantee that current checkpoints will remain justified, as finality depends on ongoing validator voting. The tool also cannot detect if validators are sharing private keys or engaging in malicious activities off-chain. It cannot verify that the consensus contract itself is secure or free from vulnerabilities — it only reports what the contract states.

PLEASE NOTE

Casper FFG Checker supports EVM-compatible chains only. It requires that the consensus contract implements standard view functions for the data displayed. Some Casper FFG contracts may use custom function names or data structures not covered by the default ABI — users can adapt the tool by modifying the ABI definition in the script. The tool is read-only and does not modify any contract state or initiate transactions. It is free to use and does not store or transmit any data off-device. Always verify consensus contract addresses from official sources before use.