Cross-Chain Bridge Route API

Cross-Chain Bridge Route API

  

Best cross-chain bridge routes via LI.FI -- 60+ chains, 18+ bridges, fees and time compared. Pay-per-call via x402 (USDC on Base L2) -- no API key, no signup, no rate-limit wall.

Part of the klymax402 marketplace -- 100 x402 micropayment APIs for AI agents, one wallet, USDC on Base.

Quickstart -- MCP

Add to your MCP client config (Claude Desktop, Cursor, ElizaOS, etc.):

{
  "mcpServers": {
    "bridge-routes": {
      "url": "https://bridge-routes.api.klymax402.com/mcp"
    }
  }
}

Quickstart -- HTTP (x402)

curl "https://bridge-routes.api.klymax402.com/api/route?fromChain=...&toChain=...&token=...&amount=..."
# -> 402 Payment Required, with an x402 payment challenge in the response body

Any x402-aware client (@x402/fetch, x402-agent-tools, ATXP) handles the 402 -> sign -> retry cycle automatically.

Tools

| Tool | Method | Path | Price | Description | |---|---|---|---|---| | bridge_find_best_route | GET | /api/route | $0.008 | Find the best cross-chain bridge route | | bridge_find_best_route | POST | /api/route | $0.008 | Find the best cross-chain bridge route (POST variant) |

bridge_find_best_route

Use this when you need to bridge tokens between different blockchains. Returns ranked bridge routes with fees and timing in JSON.

Parameters

| Name | Type | Required | Description | |---|---|---|---| | fromChain | string | yes | Source chain ID (1=Ethereum, 8453=Base, 42161=Arbitrum, 10=Optimism, 137=Polygon, 56=BSC, 43114=Avalanche) | | toChain | string | yes | Destination chain ID (1=Ethereum, 8453=Base, 42161=Arbitrum, 10=Optimism, 137=Polygon, 56=BSC, 43114=Avalanche) | | token | string | yes | Token symbol to bridge (e.g. USDC, USDT, ETH, WETH) | | amount | string | yes | Amount in smallest unit (e.g. 1000000 for 1 USDC with 6 decimals, 1000000000000000000 for 1 ETH) | | toToken | string | no | Destination token symbol if different from source (optional, defaults to same as token) |

Returns

• routes -- array of bridge options ranked by best value
• bridgeProvider -- which bridge protocol (Stargate, Across, Hop, Connext, etc.)
• estimatedTime -- expected bridge completion time in seconds
• fee -- total bridging fee in USD
• amountReceived -- expected output amount on destination chain
• steps -- detailed step-by-step route (approve, bridge, swap if needed)

Example response:

{"routes":[{"bridgeProvider":"Stargate","estimatedTime":60,"fee":0.85,"amountReceived":"999.15","steps":["approve USDC","bridge via Stargate"]}],"fromChain":"Ethereum","toChain":"Base","token":"USDC"}

When to use: moving assets cross-chain to find the cheapest and fastest bridge. Essential for multi-chain portfolio management.

Not for: gas prices (use gas_get_current_price).

bridge_find_best_route

Use this when you need to bridge tokens between different blockchains. Returns ranked bridge routes with fees and timing in JSON. POST variant of bridge_find_best_route -- same params passed as JSON body instead of query string.

Parameters

| Name | Type | Required | Description | |---|---|---|---| | fromChain | string | yes | Source chain ID (1=Ethereum, 8453=Base, 42161=Arbitrum, 10=Optimism, 137=Polygon, 56=BSC, 43114=Avalanche) | | toChain | string | yes | Destination chain ID (1=Ethereum, 8453=Base, 42161=Arbitrum, 10=Optimism, 137=Polygon, 56=BSC, 43114=Avalanche) | | token | string | yes | Token symbol to bridge (e.g. USDC, USDT, ETH, WETH) | | amount | string | yes | Amount in smallest unit (e.g. 1000000 for 1 USDC with 6 decimals, 1000000000000000000 for 1 ETH) | | toToken | string | no | Destination token symbol if different from source (optional, defaults to same as token) |

Returns

• routes -- array of bridge options ranked by best value
• bridgeProvider -- which bridge protocol (Stargate, Across, Hop, Connext, etc.)
• estimatedTime -- expected bridge completion time in seconds
• fee -- total bridging fee in USD
• amountReceived -- expected output amount on destination chain
• steps -- detailed step-by-step route (approve, bridge, swap if needed)

Example response:

{"routes":[{"bridgeProvider":"Stargate","estimatedTime":60,"fee":0.85,"amountReceived":"999.15","steps":["approve USDC","bridge via Stargate"]}],"fromChain":"Ethereum","toChain":"Base","token":"USDC"}

When to use: moving assets cross-chain to find the cheapest and fastest bridge. Essential for multi-chain portfolio management.

Not for: gas prices (use gas_get_current_price).

Example agent prompts

• "Bridge tokens between different blockchains"
• "Bridge tokens between different blockchains"

Payment

• Protocol: x402 -- HTTP-native pay-per-call, no signup, no API key
• Network: Base L2 (eip155:8453)
• Asset: USDC
• Facilitator: Coinbase CDP (primary), PayAI (fallback)
• Also reachable via ATXP (OAuth-wrapped x402, RFC 9728 protected-resource metadata)

Part of klymax402

100 x402 micropayment APIs for AI agents -- one wallet, USDC on Base, zero signup.

• Catalog: https://klymax402.com/llms.txt
• Full API reference: https://klymax402.com/llms-full.txt
• Live stats: https://klymax402.com/stats

License

MIT