Current Sate of L2 Bridges

7 November 2024

The EEA is today publishing the Ethereum L2 Working Group’s 2024 report on “the Current State of L2 Bridges”, providing an updated survey of the L2 Bridge ecosystem.

The full report of 9 pages (PDF), edited by Dr Andreas Freund on behalf of the group includes a survey of L2 Bridges with a name, brief summary, and bridge design type. Note that it does not cover token bridges for L2s or sidechains where the transfers happen from L1 to the L2, nor L1-L1 bridges.

Summary of the Update

  • L2 Bridges have become THE crucial glue of the L2 ecosystem to further L2 interoperability and efficient use of assets and applications across the ecosystem.
  • L2 Bridges still have very different trust assumptions between them, e.g., trusted vs. trustless bridges, and very different design choices, e.g., lock-mint-burn vs. liquidity networks. The ecosystem has not coalesced behind a dominant design paradigm or best practices.
  • The L2 Bridges ecosystem is still nascent and continues to be in a state of flux and growth, although the rate of change has slowed.
  • Users, in particular Enterprises, must still do their due diligence to assess which L2 bridges offer the best risk-reward profile for their needs.

    While still early in the journey toward a standardized L2 interoperability framework, recent developments show that designs have started to favor Liquidity Networks or (atomistic) Token Bridges, with some projects offering both. It will be interesting to see if the new bridge design paradigm pioneered by zkBridge that only relies on zkps will become the dominant paradigm due to its flexibility and limited trust assumptions, or if its technical complexity will prevent wider adoption. The recent work by the EEA Interoperability Group, EEA Distributed Ledger Technology Interoperability Specification Version 1.0, gives a guide on preferred bridge designs and approaches without taking into account the all-important bridge liquidity question, as this is an economic parameter related to trading and arbitrage, not a technical one. However, it is highly relevant for assessing bridge risk profiles as was discussed in the previous report.