What Is a Crypto Bridge? Cross-Chain Bridges Explained

A crypto bridge is a protocol that moves tokens or data from one blockchain to another, usually by locking the asset on the source chain and issuing an equivalent wrapped token on the destination chain. Blockchains cannot read each other's state directly, so bridges act as the go-between.

Crypto bridge definition

Ethereum, Bitcoin, Sui, MultiversX and Radix are separate ledgers. ETH cannot literally travel to Sui. What a cross-chain bridge does is keep the original asset in custody on one chain and create a claim on it, a wrapped token, on another.

A wrapped token is that claim: a token on chain B that is supposed to be redeemable 1:1 for the asset held on chain A. It is only worth what the bridge's custody and redemption guarantees are worth.

How a crypto bridge works

Most bridges use one of three models:

1. Lock and mint: you lock tokens in a contract on chain A; the bridge mints wrapped tokens on chain B. Burning them on B unlocks the originals on A.
2. Burn and mint: the issuer burns the token on A and mints the native version on B. Some stablecoin issuers do this for their own tokens, which avoids wrapped copies.
3. Liquidity networks: the bridge holds pools of the asset on both chains and swaps you out of one and into the other.

Something has to confirm that the deposit on A really happened. That verifier may be a set of validators or a multisig, an external oracle network, or a light client that checks the other chain's proofs. The verifier is where most of the trust, and most of the risk, sits. Our multi-chain DeFi explainer covers why users end up needing bridges at all.

Crypto bridge example

Say you want to use 10 ETH in a Sui DeFi app. You deposit 10 ETH into a lock-and-mint bridge contract on Ethereum. After the bridge's verifiers confirm the deposit, roughly 10 wrapped ETH appear in your Sui wallet, minus a bridge fee (hypothetically 0.05%, or 0.005 ETH) plus gas on both chains.

The 10 real ETH now sit in the bridge contract on Ethereum. If that contract or its verifiers are compromised and the ETH is stolen, your wrapped ETH on Sui is backed by nothing and its market price can collapse, even though nothing went wrong on Sui itself.

Why a crypto bridge matters

Bridges concentrate large amounts of locked value behind a small set of keys or contracts, which makes them prime targets. The Ronin bridge lost about $625 million in March 2022 after attackers obtained 5 of its 9 validator keys (Security Affairs).

• Check who verifies transfers and how many independent parties must agree.
• Prefer native or issuer-run versions of an asset over wrapped copies when they exist.
• Know which version of a token a DeFi app accepts; two "USDC" tokens on the same chain from different bridges are not interchangeable.
• Bridge only what you need, and avoid leaving large balances in wrapped form long-term.

Bridge design belongs on the checklist in how to check a DeFi protocol is safe, because a protocol built on a wrapped asset inherits the bridge's risk.

Related terms

• Multisig wallet — the multi-key setup many bridges use to approve transfers.
• Gas fees — transaction costs you pay on both sides of a bridge.
• Price oracle — external data feeds, a close cousin of bridge verifiers.
• DEX (decentralized exchange) — where bridged tokens are usually traded.
• Rug pull — exit scams that can also hit poorly run bridges.

Learn more on the JewelSwap blog

• Multi-chain DeFi explained — why liquidity is spread across chains and how users move between them.
• How to check a DeFi protocol is safe — a practical checklist that includes bridge and custody risk.
• Stablecoin chains: Tempo, Arc and Plasma — new payment-focused chains and how stablecoins move onto them.

Frequently asked questions

What is a blockchain bridge?

A blockchain bridge, also called a cross-chain bridge, is a protocol that moves assets or messages between two blockchains, typically by locking tokens on one chain and minting wrapped tokens on the other.

What is a wrapped token?

A wrapped token is a token on one chain that represents an asset held on another chain, redeemable 1:1 through the bridge that issued it. Its value depends on that bridge staying solvent and secure.

Are crypto bridges safe?

They carry extra risk. A bridge holds large pooled deposits behind a verifier set or contract, and if that is compromised the wrapped tokens can lose their backing. Some of the largest crypto hacks, such as Ronin in 2022, were bridge hacks.

JewelSwap Crypto Glossary · educational, not financial advice. Updated 2 October 2026. Browse the full glossary.