Key Features
What makes Across the fastest, cheapest, and most secure crosschain interoperability protocol.
Feature Highlights
| Feature | Details |
|---|---|
| Sub-2-second fills | Competitive relayer network delivers funds on the destination chain in ~2 seconds on mainnet |
| 26 mainnet chains | Solana, MegaETH, Plasma, Monad, Hyperliquid, and all major L2s |
| CCTP V2 / CCTPFast | Native USDC settlement up to $10M per transaction. CCTPFast offers faster attestation where available |
| Sponsored routes | Zero-fee transfers on select routes (e.g., USDC to USDH on Hyperliquid) |
| Embedded crosschain actions | Compose DeFi operations — swap, bridge, and execute destination-chain calls in a single transaction |
| OFT for USDT0 | Native USDT0 mint-and-burn settlement via LayerZero. More tokens coming soon |
| ERC-7683 standard | Implements the crosschain intent standard for interoperability with other intent-based systems |
| ZK proofs | Succinct/SP1 zero-knowledge proofs enable permissionless chain expansion without governance votes |
API Comparison
The two primary APIs for initiating crosschain transfers are /swap/approval and /swap/counterfactual. They serve different use cases and have different capabilities.
| Features | /swap/approval | /swap/counterfactual |
|---|---|---|
| How it works | Returns a transaction for the user to sign and submit on-chain | Returns a deposit address the user sends tokens to — no signing required |
| HTTP methods | GET (simple bridge) / POST (embedded actions) | GET only |
| API key required | Yes | Yes |
| Integrator ID required | Yes | Yes |
| Supported origin chains | All 26 mainnet chains | Ethereum, Optimism, Unichain, Polygon, Base, Arbitrum, World Chain |
| Supported destination chains | All 26 mainnet chains | HyperEVM (USDH, USDC), HyperCore (USDC-SPOT, USDH-SPOT) |
| Supported tokens (origin) | All bridgeable tokens (per /swap/tokens) | USDC |
| Trade types | exactInput, minOutput, exactOutput | exactInput only |
| Embedded crosschain actions | Yes (via POST with crossChainMessage) | No |
| Origin swaps | Yes (automatic if input token is not directly bridgeable) | No |
| Refund mechanism | Automatic via SpokePool to refundAddress | Built-in withdraw escape hatch (details) |
| Ideal for | Wallets, dApps, DEX aggregators — any flow with wallet signing | CEX onramps, bots, automation — flows where no wallet signing is available |
| Settlement mechanisms | Intents, CCTP, OFT (auto-selected) | CCTP, Intents (auto-selected) |
| Expected fill time | Less than 2 seconds | Less than 2 seconds |
| Deposit address TTL | N/A | 24 hours |
| Status | Generally available | Early access (request access) |
Speed
Across's relayer network fills most transfers in ~2 seconds on mainnet. Relayers compete on speed, fronting their own capital on the destination chain and getting repaid later through the settlement process.
Chain Coverage
Across supports 23+ mainnet chains including:
- EVM L2s — Arbitrum, Optimism, Base, Polygon, zkSync, Linea, Scroll, Blast, Mode, Redstone, Zora, and more
- Alt-L1s and new chains — Solana, MegaETH, Plasma, Monad
- App-specific chains — Hyperliquid (HyperCore + HyperEVM)
- Testnet support — 8 testnet chains for development
See the full list here.
Sponsored Routes
Certain routes are zero-fee — the protocol or partners subsidize the transfer cost. For example, USDC to USDH on Hyperliquid is a sponsored route with no bridge fee.
Check the /swap/approval response for fee breakdowns. Sponsored routes show 0 total fees.
Embedded Crosschain Actions
Bridge and execute in one transaction. Attach arbitrary contract calls to your crosschain transfer — the MulticallHandler executes them atomically on the destination chain.
Use cases:
- Swap + deposit into Aave
- Bridge + add liquidity to a DEX
- Transfer + stake on the destination chain
ERC-7683
Across implements the ERC-7683 crosschain intent standard, enabling interoperability with other intent-based protocols and standardized order formats.
V4 — ZK-Powered Expansion
Across V4 introduces zero-knowledge proofs via Succinct's SP1 prover for settlement verification. This enables:
- Permissionless chain expansion — new chains can be added without governance votes
- Faster settlement — ZK proofs replace the optimistic challenge period
- Reduced trust assumptions — cryptographic verification instead of economic security
See Across V4 for technical details.