Monitor & Manage Multi-Chain Wallets with FluxRail's API

Introduction

Managing wallets across multiple blockchains is a constant challenge for Web3 developers, exchanges, and fintechs. Each chain has its own RPC endpoints, event formats, and monitoring tools. FluxRail unifies this complexity into a single API, letting you monitor blockchain events and manage wallet operations across 36+ chains without touching an RPC node. In this guide, you'll learn how to use FluxRail's Core and Wallet products to watch addresses, detect transactions, and derive wallets—all with simple REST calls.

Prerequisites

You'll need a FluxRail account. Head to fluxrail.io and grab your test API key (flux_test_...) from the dashboard. All examples use the test environment; no real funds or network fees are involved.

Step 1: Subscribe to an Address

FluxRail's Core product lets you subscribe to any address or contract and receive webhooks when events occur. To monitor an Ethereum address, create a subscription:

curl -X POST https://api.fluxrail.io/api/v1/subscriptions \
  -H "X-API-Key: flux_test_xxx" \
  -H "Content-Type: application/json" \
  -d '{
    "chain": "ethereum",
    "address": "0x742d35Cc6634C0532925a3b844Bc4b9f5b3b1b3b",
    "webhook_url": "https://your-server.com/webhook",
    "events": ["native_transfer", "token_transfer"]
  }'

Response:

{
  "id": "sub_abc123",
  "chain": "ethereum",
  "address": "0x742d35Cc6634C0532925a3b844Bc4b9f5b3b1b3b",
  "status": "active",
  "created_at": "2025-03-01T12:00:00Z"
}

You can subscribe to multiple chains with the same address. For example, to also monitor the same address on Polygon, create another subscription with "chain": "polygon".

Step 2: List and Manage Subscriptions

View all your subscriptions:

curl -X GET https://api.fluxrail.io/api/v1/subscriptions \
  -H "X-API-Key: flux_test_xxx"

To update a subscription (e.g., change webhook URL):

curl -X PATCH https://api.fluxrail.io/api/v1/subscriptions/sub_abc123 \
  -H "X-API-Key: flux_test_xxx" \
  -H "Content-Type: application/json" \
  -d '{"webhook_url": "https://new-server.com/webhook"}'

To delete a subscription:

curl -X DELETE https://api.fluxrail.io/api/v1/subscriptions/sub_abc123 \
  -H "X-API-Key: flux_test_xxx"

Step 3: Receive and Verify Webhooks

When a monitored address receives a transaction, FluxRail sends a signed webhook to your endpoint. The signature is in the X-FluxRail-Signature header. Verify it using your API key secret (HMAC SHA-256). Example webhook payload:

{
  "event": "native_transfer",
  "id": "evt_xyz789",
  "chain": "ethereum",
  "address": "0x742d35Cc6634C0532925a3b844Bc4b9f5b3b1b3b",
  "tx_hash": "0xabcdef...",
  "from": "0x...",
  "to": "0x...",
  "value": "1000000000000000000",
  "block_number": 12345678,
  "timestamp": "2025-03-01T12:05:00Z"
}

You can list recent events for a subscription:

curl -X GET https://api.fluxrail.io/api/v1/events?subscription_id=sub_abc123 \
  -H "X-API-Key: flux_test_xxx"

Step 4: Derive Wallet Addresses

FluxRail's Wallet product provides stateless helpers for key management. Generate a mnemonic:

curl -X POST https://api.fluxrail.io/api/v1/wallet/mnemonic \
  -H "X-API-Key: flux_test_xxx" \
  -H "Content-Type: application/json" \
  -d '{"strength": 128}'

Response:

{
  "mnemonic": "abandon ...",
  "seed": "0x..."
}

Derive an address from a mnemonic:

curl -X POST https://api.fluxrail.io/api/v1/wallet/derive \
  -H "X-API-Key: flux_test_xxx" \
  -H "Content-Type: application/json" \
  -d '{
    "mnemonic": "abandon ...",
    "path": "m/44\'/60\'/0\'/0/0",
    "chain": "ethereum"
  }'

Response:

{
  "address": "0x742d35Cc6634C0532925a3b844Bc4b9f5b3b1b3b",
  "public_key": "0x...",
  "chain": "ethereum"
}

Validate an address:

curl -X POST https://api.fluxrail.io/api/v1/wallet/validate \
  -H "X-API-Key: flux_test_xxx" \
  -H "Content-Type: application/json" \
  -d '{"address": "0x742d35Cc6634C0532925a3b844Bc4b9f5b3b1b3b", "chain": "ethereum"}'

Response:

{"valid": true}

Step 5: Monitor Multiple Chains Simultaneously

To monitor the same address on Ethereum, Polygon, and BNB Smart Chain, create subscriptions for each chain. Use the /api/v1/subscriptions/bulk endpoint for efficiency:

curl -X POST https://api.fluxrail.io/api/v1/subscriptions/bulk \
  -H "X-API-Key: flux_test_xxx" \
  -H "Content-Type: application/json" \
  -d '{
    "subscriptions": [
      {"chain": "ethereum", "address": "0x...", "webhook_url": "...", "events": ["native_transfer"]},
      {"chain": "polygon", "address": "0x...", "webhook_url": "...", "events": ["native_transfer"]},
      {"chain": "bsc", "address": "0x...", "webhook_url": "...", "events": ["native_transfer"]}
    ]
  }'

FluxRail handles the RPC connections and event parsing for each chain. You get a unified webhook format regardless of the source chain.

Step 6: Monitor Contract Events

Subscribe to a smart contract for specific events (e.g., Transfer):

curl -X POST https://api.fluxrail.io/api/v1/subscriptions \
  -H "X-API-Key: flux_test_xxx" \
  -H "Content-Type: application/json" \
  -d '{
    "chain": "ethereum",
    "address": "0xdAC17F958D2ee523a2206206994597C13D831ec7",
    "webhook_url": "https://your-server.com/webhook",
    "events": ["contract_event"],
    "contract_abi": [{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"}]
  }'

Now you'll receive webhooks whenever a Transfer event is emitted by the USDT contract.

Step 7: Fetch Available Chains

See the full list of supported chains:

curl -X GET https://api.fluxrail.io/api/v1/chains \
  -H "X-API-Key: flux_test_xxx"

Response includes chain slugs, names, and native currency info.

Conclusion

FluxRail's Core and Wallet products give you a unified API to monitor and manage multi-chain wallets. No more juggling multiple RPC endpoints or writing custom event parsers. With one API key, you can subscribe to addresses on 36+ chains, receive signed webhooks, derive wallets, and validate addresses. Combine this with FluxRail's Pay, Liquidity, and Payouts products to build complete cross-chain payment flows. Start today at fluxrail.io and check the docs for more details.