Users deposit and lock assets on Ethereum in exchange for an equivalent amount of a corresponding token on zkSync Era. Conversely, users can withdraw assets from zkSync Era in exchange for the same amount on Ethereum.

zkSync Era Bridge is an asset bridge built on Ethereum and zkSync Era. zkSync Era Bridge was developed by Matter Labs and launched in 2023.

Matter Labs team owns and governs the protocol. Matter Labs' investors include a16z, Lightspeed Venture Partners, Blockchain Capital, etc.

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zkSync Era Bridge

# zkSync Era Bridge Average fees per user (AFPU) Methodology

## 1. Overview

Average Fees Per User (AFPU) measures the average fees collected per daily active user on the zkSync Era Bridge. The metric is calculated by dividing total daily fees by the number of daily active users. For zkSync Era Bridge, this metric is currently zero because the protocol does not charge fees for bridging operations between Ethereum Layer 1 and zkSync Era Layer 2.

## 2. Data sources

- **Ethereum event logs**: Parsed events from the L1ERC20Bridge contract including `DepositInitiated` and `WithdrawalFinalized` events
- **Ethereum event logs**: Parsed events from the Diamond contract including `EthWithdrawalFinalized` and `NewPriorityRequest` events  
- **Ethereum transaction data**: Function calls to the Diamond contract's `requestL2Transaction` function
- **End-of-day token price feeds**: Used for USD conversion in related transfer volume calculations
- **Token metadata**: Contract addresses and decimal place information for proper amount calculations

## 3. Step-by-step calculation

### Component A: User identification and classification
- **Purpose**: Identify and classify all users who interact with the zkSync Era Bridge on a daily basis
- **Logic**: Extract user addresses from three types of Ethereum bridge interactions. Depositors are identified from `DepositInitiated` events using the `from` field and from successful `requestL2Transaction` function calls using the `from_address` field. Withdrawers are identified from `WithdrawalFinalized` and `EthWithdrawalFinalized` events using the `to` field. Each interaction is timestamped and classified by user type (Depositor or Withdrawer) and includes chain, market sector, and business segment metadata.
- **Key fields**: `user_address`, `user_type`, `block_timestamp`, `chain`, `market_sector_id`, `business_segment_id`

### Component B: Daily active user aggregation  
- **Purpose**: Count unique daily active users across different dimensional breakdowns using probabilistic counting
- **Logic**: Aggregate user interactions by truncating timestamps to daily boundaries. Use HyperLogLog functions to count distinct users, which handles potential overlaps when users perform multiple interactions per day. Create separate aggregations for project-level totals, chain-level breakdowns, user-type breakdowns (Depositor vs Withdrawer), and product-level breakdowns. Apply chain availability filtering to ensure data completeness.
- **Key fields**: `user_dau` (distinct user count), `timestamp`, `dimensions`, `chain_id`, `user_type`, `product_id`

### Component C: Fee calculation
- **Purpose**: Calculate total fees collected by the bridge protocol
- **Logic**: Set fees to zero for all time periods and dimensional combinations. Use the same timestamp, chain, and product structure as the transfer volume metric to maintain consistency across metrics, but assign zero values to the `fees` field since zkSync Era Bridge does not charge bridging fees.
- **Key fields**: `fees` (always 0), `timestamp`, `chain_id`, `product_id`

### Final aggregation
- **Combining components**: Apply the ARPU calculation formula by dividing total daily fees by daily active users using the `calculate_arpu` macro, which matches records by timestamp and dimensional attributes
- **Currency conversion**: No currency conversion needed since fees are zero
- **Time aggregation**: Daily boundaries established through timestamp truncation to day level
- **Final calculation**: AFPU = Daily Fees ÷ Daily Active Users. Since fees are always zero, the result is always 0 regardless of user count. The calculation is finalized using standardized metric schema and gap-filling strategies to ensure complete time series data.

*This methodology was automatically generated by Token Terminal's methodology analyzer.*

zkSync Era Bridge

Average fees per user (AFPU)

Average fees per user (AFPU)

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