Cross-Chain Bridge Integration in a Mobile Crypto Wallet
The most common scenario in a mobile crypto wallet: a user sends USDC from Ethereum to Polygon, and the funds get stuck during finalization. Without correct tracking, this causes panic and negative support tickets. We solve this by integrating cross-chain bridge aggregators with full status monitoring. Over 5 years, we have implemented bridge functionality for 15+ crypto wallets and handled hundreds of thousands of cross-chain transfers. Our experience allows us to anticipate typical problems: insufficient bridge liquidity, destination network configuration errors, delays due to forks. We have solved and documented each such case so that users never lose funds.
How do bridge aggregators work?
Aggregators are middleware that combine multiple bridge protocols into a single API. The app sends a transfer request, and the aggregator calculates the best route by speed, fee, and final amount. We use proven solutions: Li.Fi, Squid Router, Stargate Finance. Each has its strengths. Compare them:
| Aggregator | Network Coverage | Transfer Time | Fee | Features |
|---|---|---|---|---|
| Li.Fi | 20+ EVM, Cosmos (via Squid) | 1-20 min | 0.1-0.5% + fixed | Built-in recovery |
| Squid Router | EVM, Cosmos, Polkadot | 2-15 min | 0.3-0.8% | Routing via Axelar |
| Stargate (LayerZero) | Major EVM | 3-10 min | ~$2 fixed | Stablecoins only |
Li.Fi is the most flexible, supporting recoverTx for stuck transfers. Squid is better for Cosmos. Stargate is simple and fast for USDC/USDT.
How to choose the right bridge for your wallet?
Consider: which networks do your users need? Which tokens? If only EVM and stablecoins, Stargate is sufficient. If Cosmos or Polkadot are needed, we integrate Squid via Li.Fi. In any case, integration through an aggregator gives one API for dozens of bridges.
// iOS — routes via Li.Fi SDK import LiFi let lifi = LIFI() let routesRequest = RoutesRequest( fromChainId: 1, // Ethereum toChainId: 137, // Polygon fromTokenAddress: "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48", // USDC toTokenAddress: "0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174", fromAmount: "100000000" // 100 USDC (6 decimals) ) let routes = try await lifi.getRoutes(request: routesRequest) Detailed API description can be found in the Li.Fi documentation.
Routing and bridge selection
Li.Fi returns multiple routes with different parameters. Show the user:
| Route | Time | Fee | You receive |
|---|---|---|---|
| Stargate | ~5 min | $2.50 | 97.5 USDC |
| Hop Protocol | ~20 min | $1.80 | 98.2 USDC |
| Across | ~3 min | $3.10 | 96.9 USDC |
Default sorting by maximum output. Provide a toggle "faster" / "cheaper".
How to implement background transfer tracking?
After sending the transaction in network A, the user gets a txHash in the source chain. Funds will appear in the destination chain after some time, depending on the finalization mechanism.
Li.Fi provides a status API: GET /v1/status?txHash={hash}&fromChain={chainId}&toChain={chainId}&bridge={bridgeName}. Statuses: PENDING → DONE / FAILED.
// Android — polling bridge status suspend fun pollBridgeStatus(txHash: String, fromChain: Int, toChain: Int): BridgeStatus { repeat(180) { // 30 minutes * 10 sec delay(10_000) val status = lifiBridgeApi.getStatus(txHash, fromChain, toChain) if (status.status == "DONE" || status.status == "FAILED") return status } return BridgeStatus(status = "TIMEOUT") } Background polling via WorkManager (Android) or BackgroundTasks (iOS) so the user gets a push notification on completion, even if the app was closed.
Handling stuck transfers
Some bridges do not automatically refund on error. Li.Fi provides a recoverTx API for some cases. You need to store the entire bridge transaction history locally with the ability to recheck and a link to bridge support. We guarantee that no transaction goes unattended — all statuses are logged and accessible in the interface. If funds haven't arrived within 30 minutes, the user can initiate a recheck. In rare cases, manual recovery via the aggregator's API is needed — our engineers assist with this as part of support.
Our integration process
- Requirements analysis: supported networks, tokens, use cases.
- Aggregator selection and architecture design.
- API call implementation and response handling.
- Background tracking with push notifications.
- Testing on testnets (Rinkeby, Goerli, Mumbai) with real transactions.
- Production deployment and monitoring.
What is included in the work
When ordering integration, we provide:
- Integration documentation for the aggregator and architecture.
- Access to API and SDK with code examples for iOS and Android.
- Training of the client's team on bridge functionality.
- Support during testing and deployment.
- Warranty support after launch.
Timeline
Integration through an aggregator with one supported route: 1-2 weeks. Multi-aggregator system with route selection, background tracking, and history: 3-6 weeks. Contact us — we will estimate your project in one business day. We are ready to implement cross-chain functionality in your wallet — get a consultation from an engineer with 10 years of experience in mobile development turnkey.