Key Features
What makes Across the fastest, cheapest, and most secure crosschain interoperability protocol.
Integration methods
Across supports three integration methods. The Swap API is the default and covers most use cases.
| Method | What it is | Use when |
|---|---|---|
| Swap API (primary) | Quote a route, then execute the returned transaction from the user's wallet | All Standard integrations — the primary path |
| Gasless | The user signs a message; Across submits the transaction on-chain, no gas from the user | You want users to transact without holding gas |
| Deposit address | Send funds to a persistent infinite-TTL address to conduct a crosschain swap | automation, on-ramps, deposit flows |
Feature Highlights
| Feature | Details |
|---|---|
| Sub-2-second fills | Competitive relayer network delivers funds on the destination chain in ~2 seconds on mainnet |
| 28 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 USDT/USDT0 → USDC-SPOT/USDC-PERPS on HyperCore from Ethereum, Arbitrum, Monad, Polygon, Unichain. |
| 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 28 mainnet chains | Ethereum, Optimism, Unichain, Polygon, Base, Arbitrum, World Chain, Linea, Ink, Monad |
| Supported destination chains | All 28 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 | N/A — amount agnostic (see details) |
| 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 infrastructure fills most transfers in ~2 seconds on all supported chains, so funds reach the recipient on the destination chain almost immediately.
Chain Coverage
Across supports 28 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
Select routes have zero bridge fees, subsidized by the protocol or partners.
Currently sponsored:
- USDT / USDT0 → USDC-SPOT, USDC-PERPS on HyperCore from Ethereum, Arbitrum, Monad, Polygon, Unichain
Sponsored routes change over time. Check the /swap/approval response for fee breakdowns to see if a route is currently sponsored.
Embedded Crosschain Actions
Bridge and execute any arbitrary action (like swap, mint, deposit etc.) 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