Bridges are protocols that facilitate the transfer of assets and data between blockchains. Each type of bridge (i.e., multisig, optimistic, and zero-knowledge) offers different tradeoffs between security, complexity, and performance.
Ethereum’s cumulative TVL held in bridges increased ~40% between 2021 and 2023. This has started to retrace as users moved assets from Ethereum to Layer-2s (L2s) and other chains.
The Vara ⇌ Ethereum Bridge, now live on mainnet, uses zero-knowledge proofs to enable trustless asset transfers between Vara Network and Ethereum.
Gear Technologies, the infrastructure provider behind the Vara Network, is expected to launch Vara.eth on testnet in Q4 2025. This application layer will enable Ethereum-based applications to offload intensive computations, thereby improving scalability and performance across the network.
Primer
Vara Network (VARA) is a Layer-1 blockchain built on the Gear Protocol, a Substrate-based smart contract platform for the development of decentralized applications (dApps). Specifically, Gear Protocol uses the actor model, where smart contracts and users are independent actors with private states that communicate through asynchronous messages, allowing parallel execution. Other key features include WebAssembly (Wasm) execution and persistent memory.
In addition to implementing Gear Protocol’s features for dApp development, Vara supports gasless and signless transactions. Gasless transactions are enabled through a voucher system, allowing developers to issue vouchers that cover gas fees so that users can interact with dApps on Vara Network without holding any VARA tokens. To facilitate signless transactions, Vara Network implements temporary sub-accounts to which users grant signing rights, allowing dApps to execute actions on their behalf without requiring them to manually sign every transaction.
The network is secured by a Nominated Proof-of-Stake (NPoS) mechanism, where VARA tokenholders nominate validators, earn a portion of their staking rewards, and bear slashing risk. In addition to securing the network through staking, VARA is used to settle transaction fees and participate in governance, which uses the OpenGov framework. Vara Network also has several initiatives to support developers building on Vara, such as Gear Academy (a free Web3 development education platform), Vara Grants (a grant program), and Varathon (an online hackathon).
Bridges facilitate the transfer of assets or data between different blockchains. They enable cross-chain interoperability, promote broader access to liquidity pools across ecosystems, and can reduce congestion by distributing activity across multiple chains. The most common bridging mechanism is ”lock-and-mint,” in which a user deposits tokens into a smart contract on a source chain where they are locked as collateral. After the deposit is confirmed, an equivalent amount of wrapped tokens is minted on a destination chain, representing said locked assets. The assets on the destination chain are burned to release the original assets on the source chain.
Types of Bridges
There are several types of bridges, each with different mechanisms and tradeoffs. For example, trusted bridges rely on a centralized entity that receives the asset onchain and mints the corresponding wrapped asset on a destination chain. Trusted bridges typically offer lower gas fees and quicker transactions than trustless bridges, but their limited decentralization introduces security vulnerabilities. For example, Multisig bridges, the most common type of trusted bridge, use a multi-signature wallet to authorize cross-chain transactions, making the bridge’s security dependent on the assumption that a majority of signers will not collude, be compromised, or become unavailable. Multisigs can be corrupted in several ways, such as key leakage, internal collusion, or signers being misled into authorization. Historically, multisig bridges have been the target of several high-profile exploits, most notably the Ronin and Multichain breaches.
In contrast, trustless bridges validate transactions using algorithms and smart contracts rather than relying on a centralized entity. They offer greater decentralization and transparency because validation occurs onchain; however, they typically have higher gas fees and latency due to the increased computational complexity required for onchain verification. Optimistic bridges are another common type of trustless bridge, used by Optimism and Arbitrum. Optimistic bridges assume messages are valid, but delay final execution to allow time for a permissionless actor to submit a fraud-proof challenge to halt the execution of a malicious message. If no challenge is submitted during the dispute window, the message is finalized. zkBridges are another type of trustless bridging mechanism, detailed in the next section.
ZK
Zero-knowledge (ZK) technology is a cryptographic technique that allows one party to prove the possession of information to another party without revealing the underlying data itself. This is done through zero-knowledge proofs (ZKPs). The two most common ZKPs used in blockchain are zk-SNARKs (succinct non-interactive arguments of knowledge) and zk-STARKs (scalable transparent arguments of knowledge). Layer-2 protocols frequently use ZKPs to scale Ethereum by bundling transactions into ZK rollups (e.g., ZKsync, Starknet, and Polygon zkEVM). These rollups generate cryptographic proofs of validity and submit only those proofs to the Layer-1 blockchain, allowing large volumes of transactions to be processed offchain while the Layer-1 handles the final verification onchain. ZKPs enhance confidentiality and security by verifying sensitive information without disclosing underlying data or relying on a centralized intermediary.
Putting it Together: zkBridges
zkBridges are trustless bridges that generate ZKPs offchain that verify the validity of a finalized state or transaction on a source blockchain. These proofs are then verified onchain on a destination chain without exposing the underlying data, offering data integrity and trustlessness. However, zkBridges have the most complex architecture of the above-mentioned bridging models. Producing a ZKP to prove an event on one chain typically requires developing chain-specific logic to generate ZKPs to account for different consensus mechanisms. Additionally, proof generation is computationally intensive and time-consuming, which can result in increased latency for users. Here is an example of how a zkBridge transfers tokens:
A user deposits tokens into a bridge smart contract on the source chain, generating an event that must be proven on the destination chain.
An offchain node (prover) constructs a ZKP to validate that the event occurred as claimed.
The ZKP and other necessary data (e.g., block headers or Merkle roots) are sent to a verifier contract deployed on the destination chain.
The verifier contract validates the ZKP, and the bridge contract mints the equivalent amount of tokens (e.g., wrapped or canonical representations) or releases previously locked collateral held in a liquidity vault.
The rise of Layer-2 rollups (e.g., Arbitrum, Polygon, zkSync) and alternative Layer-1s (e.g., Solana, Sui) has shifted computational activity off Ethereum’s mainnet, positioning Ethereum primarily as a settlement and security layer. By moving activity to other blockchains (such as Ethereum L2s), users and developers can access lower fees, faster finality, and greater scalability while relying on Ethereum for settlement, security, liquidity, and other ecosystem benefits (e.g., wallet compatibility, token standards, and access to a broader user base). This shift is reflected in the growth of Ethereum’s bridged TVL (i.e., an increase in bridged TVL means that value is flowing out of Ethereum and onto other blockchains), which increased ~35% between 2021 and 2023, and has since begun to retrace.
Specifically, in late 2021 and early 2022, bridges began to emerge more rapidly to connect Ethereum with Layer-2 rollups, notably, the launch of the Arbitrum bridge and Optimism bridge in August 2021. This shift drove over $10 billion in capital outflows from Ethereum and into bridge contracts. In February 2022, bridged TVL peaked at over $27.5 billion, accounting for ~35% of Ethereum’s cumulative TVL.
Over time, Ethereum bridged TVL has shifted to concentrate primarily on a few dominant L2s, with the following points outlining the respective development timeline:
August 2021: Launch of three major bridges - Optimism, Arbitrum, and Wormhole.
September-October 2021: Bridged TVL across all networks increased by ~75%, from $13.6 billion to $23.2 billion, during which the share of Ethereum’s cumulative TVL in bridges increased by ~10%, from 16.4% to 26.0%. This indicates more assets were locked in bridge contracts, moving their liquidity from Ethereum to another network.
October 2021-November 2023: The share of Ethereum’s cumulative TVL in bridges continued to increase, reaching ~40.0% ($10.6 billion) in November 2023. During this period, most bridged TVL was concentrated on a few chains, with Polygon and Arbitrum consistently capturing the majority, with Arbitrum alone exceeding a 50% share at several points.
August 2023-Present: This balance shifted after Base launched on Aug. 9, 2023. Within a year, Base captured ~10.0% (~$1.8 billion) of Ethereum’s bridged TVL. Base’s share has continued to increase over time, currently capturing ~40.0% of said TVL. The share of Ethereum’s cumulative TVL in bridges increased until it peaked on Oct. 13, 2023, at 44.3%. It has trended downward since, reaching ~23.0% as of June 2025.
These developments illustrate how bridges have shifted liquidity and activity away from Ethereum mainnet, with most of it consolidating onto a few major L2 networks.
Introducing the Vara ⇌ Ethereum Bridge
Bridges have shifted activity to blockchains with lower fees and faster finality, while keeping interoperability with Ethereum’s liquidity and composability. The Vara zkBridge extends this by connecting Vara Network and Ethereum in a decentralized and trustless manner via ZKPs and an onchain Ethereum light client that verifies messages without a centralized intermediary. The bridge is already live on mainnet via Eitherway, Vara’s supported interface, has completed a security audit, and is currently on mainnet as of October 28, 2025. Additionally, the developer portal provides APIs, SDKs, and technical documentation to support developer onboarding.
The Technology
At a high level, the bridge design relies on two core components: (1) ZKP-based message verification for Vara Network-originated transfers and (2) an onchain Ethereum light client with Sync Committee integration for verifying Ethereum state.
ZKP-Based Message Verification
When bridging from Vara Network to Ethereum, the bridge uses a ZKP system that allows Ethereum to trust messages finalized on Vara without relying on a centralized entity. This process uses cryptographic proofs to demonstrate that a message was included in Vara’s state and signed by the active validator set, while keeping all underlying transaction data private. By verifying these proofs onchain, Ethereum can execute bridging operations without additional trust assumptions. Below is an operational flow that shows how ZKPs are used by the Vara ⇌ Ethereum Bridge Vara’s when bridging from Vara to Ethereum.
The tokens the user wishes to bridge are locked, generating a message that is added to an outbound message queue. A new Merkle root of the message is computed when a new block is produced on Vara, which occurs approximately three seconds later.
A ZKP is generated by permissionless relayers to validate that the Merkle root was signed by Vara’s active validator set (66 total validators). Relayers are independent, permissionless actors that transport zk-proofs, Merkle roots, and finalized headers between Ethereum and Vara. Relayers do not possess the ability to validate or interpret the data they carry, but they can earn rewards for successfully transporting messages. Relayers do not possess the ability to validate or interpret the data they carry, but they can earn rewards for successfully transporting messages.
Relayers may claim rewards from users via optional bridging fee contracts.
The fee is typically small and included when the user initiates the cross-chain message.
Rewards are claimed onchain, where multiple relayers can compete to complete the task.
If one relayer goes offline, another can pick up the task, ensuring liveness.
The ZKP, Merkle root, and transaction data are submitted to the proof verification contract on Ethereum, where it is validated using gnark, a zk-SNARK library for generating and verifying proofs.
Once verified, a message (e.g., mint tokens) can be submitted to the Bridge Message Contract along with a Merkle proof of inclusion.
The contract checks that the message belongs to an approved Merkle root and has not been previously processed. Once the contract verifies this, the corresponding message action is executed.
Built-in Ethereum Light Client and Sync Committee Integration
On the other hand, when bridging from Ethereum to Vara Network, an onchain Ethereum light client is used to verify that events are finalized without relying on a centralized entity for verification. Specifically, the light client tracks Ethereum block headers and validates consensus signatures from the Sync Committee to verify a message has been confirmed by Ethereum’s consensus mechanism. This approach allows Vara to prove the Ethereum state trustlessly and execute bridging actions without running a full Ethereum node. Below is an operational flow that shows how the built-in light client functions when bridging from Ethereum to Vara:
A user deposits tokens into the bridge contract on Ethereum, generating a bridging event.
Relayers continuously monitor Ethereum’s Beacon Chain, the consensus layer that finalizes blocks, and the Sync Committee, a rotating group of 512 validators that sign block headers to prove finality.
When a block is finalized, a relayer submits the block header and corresponding Sync Committee signatures to Vara’s built-in Ethereum checkpoint light client, which verifies the block is finalized.
After the block’s finality is verified, the bridging event within that block can be proven by Vara using a Merkle inclusion proof, and the bridging action is completed.
Upcoming Vara.eth Testnet Launch
The Gear Technologies team is also launching Vara.eth on testnet in Q4 2025, which will be an application layer that Ethereum dApp developers can integrate to offload computation from Ethereum to improve latency and gas fees. Unlike Vara Network, a Layer-1 blockchain on which developers can build and deploy dApps, Vara.eth is an execution layer for both stateless and stateful computations. It can be integrated either natively or with an event-based model into Ethereum dApps to scale them without relocating off the Ethereum mainnet. When called, Vara.eth validators will compute the program and send the results to a Gear contract on Ethereum for execution. The above diagram illustrates native integration of Vara.eth, showing a workflow where the dApp (i) calls Vara.eth to perform computation, (ii) the sequencer aggregates and batches the signed results, and (iii) Vara.eth returns the results via its smart contracts, which then deliver them to the dApp’s smart contract. Validators on Vara.eth that perform the computation must stake collateral that is subject to slashing in the event of dishonesty. Vara.eth inherits the features of Gear Protocol mentioned in this report’s “Primer” section, such as WebAssembly (Wasm) execution and persistent memory, which validators implement to run efficient computation.
Future Outlook
Bridges that power interoperability with Ethereum are emerging as essential infrastructure, particularly as traditional financial institutions begin to explore blockchain technology and are drawn to Ethereum for its dominance in DeFi activity and stablecoin issuance. BlackRock’s BUIDL fund expanding to Arbitrum and Optimism, alongside WisdomTree’s integration of multiple Ethereum L2s into its tokenized asset platform, highlights Ethereum’s role as programmable financial infrastructure. For developers on Vara, this creates new opportunities to reduce fragmentation on Vara-native dApps and integrate with Ethereum-native assets and protocols. For example, a gaming developer on Vara could incorporate Ethereum NFT marketplaces into their dApp. As multichain ecosystems evolve and traditional finance turns to Ethereum as an infrastructure layer, bridge design will need to become more abstracted to attract Web2 users. Simple interfaces where users do not realize they are making a cross-chain transaction will support future mainstream adoption. AI agents could play a key role in simplifying UX, especially for multichain asset transfers, allowing users to interact with complex bridging operations through a single command.
Closing Summary
The Vara ⇌ Ethereum Bridge uses ZKPs and a built-in Ethereum light client to create a decentralized and secure bridge between Vara Network and Ethereum. The bridge is currently live on Mainnet. For developers and users, this will unlock access to deeper liquidity and broader composability with Ethereum.
In addition to the bridge, the Gear Technologies team will launch Vara.eth on testnet in Q4 2025, which will serve as a decentralized application layer. Unlike rollups or separate L2s, it will operate directly within the Ethereum ecosystem, offering high-performance execution through a WASM-based actor model. It supports both zk-verified and PoS-backed modes, allowing developers to choose between Ethereum-level security and faster, cheaper execution.
The mainnet launch of Vara’s zkBridge and the upcoming testnet launch of Vara.eth highlights how Vara and Gear Technologies combine a developer-friendly Layer-1 with trustless interoperability and scalable compute. By bridging from Ethereum and providing tools like gasless and signless transactions, Vara makes it easier for developers to build and for new users to interact with reduced onboarding friction.
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Natalie is a Research Analyst Intern at Messari. She is a student at Vanderbilt University studying economics. Her interests include DeFi, infra, music, and nature.
Natalie is a Research Analyst Intern at Messari. She is a student at Vanderbilt University studying economics. Her interests include DeFi, infra, music, and nature.
