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Bridge Assets

Move tokens between external EVM chains and STRATO.

In the app, bridging in lives on Fund and bridging out lives on Bridge Out. Both are in the sidebar under TRADE.

Networks and assets change

The Fund and Bridge Out pages list the networks and tokens currently enabled on-chain. Use those lists as the source of truth.

Supported Networks

When this page was written (September 2026), the bridge contract had these external chains enabled:

STRATO network External chains
Mainnet (app.strato.nexus) Ethereum, Base, Linea, Robinhood Chain, HyperEVM
Testnet (app.testnet.strato.nexus) Ethereum Sepolia, Base Sepolia, Robinhood Chain Testnet, HyperEVM

Each asset is enabled per chain. A token may be bridgeable from one chain and not another.

Fees

  • On the external chain you pay that chain's gas from your external wallet (approval plus deposit).
  • On STRATO every transaction costs 0.01 USDST, or one voucher if you hold one. Bridging out takes STRATO transactions (approval plus request), and the Transaction Summary shows the fee.
  • Deposit actions (auto-save, auto-forge) and Buy Metals show any conversion fee on their cards before you confirm.
  • Vouchers: when a bridge-in deposit is confirmed, the bridge service mints transaction vouchers to the recipient (currently 25 per confirmed deposit). Vouchers can't be transferred. See Transaction Vouchers.
  • A STRATO transaction pays its fee even if it reverts.

Bridge In (Fund)

  1. Open Fund. Under How Are You Funding?, choose Bridge In (the card lists the enabled networks). Buy Metals is covered at the end of this section.
  2. Click Connect External and connect the wallet that holds the tokens, for example MetaMask.
  3. Pick the source network and the token you're sending, and enter the amount in You Send.

  4. Choose what you receive. Each card shows the estimated amount:

    • The bridged token itself. On mainnet, bridged tokens keep their usual symbols (for example ETH, WBTC, sUSDS). Stablecoin routes can deliver USDST.
    • Auto-save: the deposit is converted to USDST and put in the USDST Savings Vault, and you receive saveUSDST
    • Auto-forge: the deposit is converted into a metal token such as GOLDST or SILVST through MetalForge

    Auto-save and auto-forge appear only for routes and chains that support them.

  5. Click Deposit, or Redeem to STRATO for a native-token route (see Native STRATO Tokens). Approve the token if prompted, then confirm the deposit in your external wallet.

  6. Follow progress in Recent Transactions next to the form.

Rebasing tokens

For rebasing tokens the app shows a notice. The amount you receive on STRATO reflects your underlying share at the current rebase multiplier, so it can differ from the token quantity you sent.

What Happens Behind the Scenes

  1. Your deposit goes to the bridge's deposit contract on the external chain.
  2. The bridge relayer sees it and records it on STRATO's MercataBridge contract (Initiated). Each external transaction can be recorded only once.
  3. The relayer verifies the deposit:
    • If it checks out: the deposit is confirmed and the tokens (or USDST) are minted to your STRATO address (Completed).
    • If it doesn't: the deposit is held for manual review (Pending Review) and later confirmed or aborted.

Buy Metals

Buy Metals ("Gold, Silver & more") uses tokens you already hold on STRATO to mint a metal token through MetalForge. It does not bridge. The card shows the spot price and fee.

Bridge Out

  1. Open Bridge Out.
  2. Click Connect External Wallet. That wallet's address is where the tokens will be sent.
  3. Choose the destination network and token, and enter the Amount.
  4. Check the summary:
    • Transaction Fee
    • Max Per Withdrawal: a per-transaction cap set for the route
    • Outcome
  5. Click Bridge Out and confirm in Confirm Bridge Transaction.

The app confirms the request is pending approval. The Bridge Out Summary shows Total Bridged Out (30d) and Pending Bridge Outs, and Bridge Out History lists your requests.

Bridge outs are not instant

The app states that bridge outs are processed within 1-3 business days and depend on available liquidity. Double-check the destination address: transfers on the external chain can't be reversed.

What Happens Behind the Scenes

  1. Your tokens move into escrow in MercataBridge (Initiated).
  2. The relayer builds the payout transaction on the external chain (Pending Review):
    • Small withdrawals: at or under a per-token threshold, and only on chains with a hot wallet configured, the payout can come from that operational hot wallet.
    • All other withdrawals: proposed to the bridge's Safe multisig custody wallet and executed only after the Safe's signers approve.
  3. Once the payout executes, the withdrawal is finalized and the escrowed tokens are burned (Completed).
  4. A withdrawal that isn't processed can be Aborted, which refunds the escrowed tokens to you. The contract lets you abort your own request only if it is still Initiated 48 hours after you made it. The app has no button for this, so contact support.

Native STRATO Tokens

Tokens that originate on STRATO use a separate native bridge (StratoNativeBridge). When this page was written, the native route to Ethereum covered USDST, GOLDST, SILVST, STRATO and saveUSDST.

  • Bridging out locks the token in a STRATO custody vault. A representation token is then minted on the external chain after an attestation. Amounts under the route's instant threshold go through after a fixed delay; larger ones need approval through the external chain's admin Safe.
  • Bridging in ("Redeem to STRATO") burns the representation token on the external chain and unlocks the original on STRATO.

Tracking and Statuses

Open View Transactions (on Bridge Out) or the transaction links on Fund to see all bridge activity.

Status Meaning
Initiated Recorded on STRATO, waiting for the relayer
Pending Review Deposit: held for manual verification. Withdrawal: payout proposed or in progress on the external chain.
Completed Finished
Aborted Cancelled. Escrowed withdrawal tokens are refunded.

Trust Model

  • The bridge depends on an off-chain relayer to observe deposits and execute payouts. STRATO does not run a light client of the external chains.
  • External-chain funds are held in a Safe multisig custody wallet, plus an optional hot wallet for small payouts on some chains.
  • Admins (STRATO governance through AdminRegistry) can pause deposits and withdrawals separately, set per-route limits and the relayer, and in an incident move in-flight withdrawal escrow to a triage wallet.

See Safety.

Common Issues

Problem What to do
Deposit shows Pending Review It's held for manual verification. Contact support with your external transaction hash if it stays there.
Bridge out still pending Bridge outs can take up to the processing window shown in the app. Check Bridge Out History, then contact support with the request details.
"Bridge capacity reached" The route's limit is currently reached. Try a smaller amount or later.
Token or network missing That route isn't enabled. Check again later or use another chain.

Next Steps

Support: support.blockapps.net