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