Overview

Transaction Simulation lets you preview the expected results of a contract or program call transaction before signing it. When using decentralized applications (dApps) or interacting directly with smart contracts, transactions can contain complex information that's difficult to parse. Simulating them first helps you confirm your intended action is reflected correctly, identify unexpected balance changes, and catch potentially malicious calls. Estimates are based on blockchain simulation and may not reflect exact results.

After initiating a contract or program call transaction on Fireblocks, the transaction is sent to your Fireblocks mobile app or via the Fireblocks API for approval. The approval request includes the expected events and balance changes for the transaction. Tap these estimates to view further details.

Transaction Simulation provides estimates for the following contract or program call operations:

• Approvals
• Wrap
• Unwrap
• Swap
• Stake
• NFT purchase
• Mint
• Burn
• Cancel order
• Borrow

If a transaction contains unsupported events, simulated estimates will not appear for it. This does not affect the approval flow; you can still proceed with the transaction.

Transaction simulation details

The approval request in your Fireblocks mobile app displays the following information for each simulated transaction:

• The number of supported events simulated in the transaction
• The network on which the transaction will occur
• The estimated USD balance change
• Details for each event

Event types

Transaction Simulation displays the following event types:

• Outgoing
• Incoming
• Mint token
• Burn token
• Approval

When a transaction includes multiple actions, such as more than one token transfer, the actions are grouped as outgoing or incoming.

Event details

Each event in the simulation displays the following information:

• The event name and icon
• The asset name and amount
• The USD value

Event representation

Events are color-coded based on their value:

• Events with a positive amount are highlighted in green.
• Events with a negative amount are highlighted in white.
• Approval events are highlighted in yellow.

Expanded simulation view

Tap the transaction simulation to expand it and see the full set of estimates. The expanded view organizes information into two tabs: Events and Assets.

• Events: Shows all actions that will take place during the transaction, including outgoing and incoming transfers, mints, burns, and token approvals. Each event shows the token amount and USD value.
• Assets: Shows all assets involved in the transaction, including the token name, contract address, amount, and USD value.

Supported blockchains

Currently, the Transaction Simulation feature only covers contract or program call transactions on EVM and Solana Blockchain, specifically. For inquiries about networks not listed here, contact your Customer Success Manager.