Account Traffic Control monitors your vault accounts for stuck transactions on blockchains and sends real-time webhook and console notifications before delays escalate.
What is Account Traffic Control?
Account Traffic Control (ATC) is a proactive transaction monitoring feature that continuously tracks the health of your vault accounts, primarily on EVM blockchains. When a transaction gets stuck, ATC detects it in real time and sends an actionable webhook alert so you can resolve it before it affects activity downstream.
ATC monitors each combination of vault account and base asset (for example, Vault 5 on ETH) and continuously re-evaluates the stuck state as conditions change.
Why this matters
EVM blockchains use a sequential nonce system, where each transaction from a given address is numbered and must be processed in order. When one transaction gets stuck, every later transaction from the same vault account and blockchain waits behind it. There is no way to skip a nonce.
Without proactive visibility, most teams discover stuck transactions reactively: through user complaints, manual inspection, or custom-built monitoring on top of Fireblocks. ATC closes that gap by surfacing the problem the moment it appears, along with a specific recommended action.
How to configure webhook notifications?
Navigate to the Developer Center.
Select Webhooks.
Create or edit a webhook.
Under Transactions, select transaction.stuck.alert.
Check the alert: you can now automate your stuck transaction workflows.
How to respond to an alert
Every alert includes a recommendedAction field with a stuckTxId (the transaction ID you need to act on).
For low-fee issues, use that ID to submit a replacement transaction with a higher fee, or drop the original transaction entirely. Both options unblock the queue behind the stuck transaction. For step-by-step instructions, see Boost or drop a stuck EVM-based transaction.
How it works
Account Traffic Control (ATC) watches each vault account and base asset combination continuously. When ATC determines that a transaction is stuck, it sends a transaction.alert.stuck webhook event containing everything you need to act on the issue:
- The affected vault account and base asset
- The number of transactions blocked behind the stuck transaction
- The last completed nonce
- The number of blocks elapsed since the transaction got stuck
- A specific recommended action (for example, boosting the transaction)
- The transaction ID to act on
The detection threshold is managed internally and may be refined over time as Fireblocks tunes the feature.
Console notifications
In addition to webhook alerts, ATC surfaces stuck transaction alerts directly in the Fireblocks Console under the notification bell. Alerts appear as Stuck transactions detected and include the affected vault account, asset, and status (for example, "4 ETH transactions in vault account 0 are stuck in CONFIRMING status"), along with a prompt to take action.
Selecting the notification opens the Replace stuck transaction dialog, with the original stuck transaction already pre-filled. Select Boost or Drop using Replace-by-Fee (RBF) without leaving the Console.
Supported transaction statuses
Account Traffic Control currently monitors transactions in the CONFIRMING and BROADCASTING statuses on supported networks.
Supported blockchains
- AVAX
- BASECHAIN_ETH
- BNB_BSC
- ETH
- ETH-AETH
- ETH-OPT
- ETH-TEST5
- MATIC_POLYGON
- WORLDCHAIN
Escalating alerts
Account Traffic Control does not fire once and stop, but rather continuously re-evaluates each stuck state. Instead of a fixed severity label, ATC adjusts how frequently it alerts based on how many transactions are piled up behind the stuck one: the more transactions are blocked, the faster the alerts fire. Treat each alert as the most up-to-date view of the stuck account.