Tatum provides you access to the blockchain via RPC.

Here's a guide on how to retrieve the token balance of an ERC-20 token from a blockchain address via RPC call. This makes use of standard eth_call via balanceOf() to call a SmartContract ABI.

ERC-20 or compatible

Steps

Step_1: Fetch the Smart Contract Address

• For example USDC over ETH: 0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48

Step_2: Fetch the Wallet Address

From which you want to retrieve the token balance

1. For example: 0xCD531Ae9EFCCE479654c4926dec5F6209531Ca7b
2. Exclude the 0x --> CD531Ae9EFCCE479654c4926dec5F6209531Ca7b

Step_3: Make an RPC call with the method eth_call

Example request:

• "to" is the ContractAddress for USDC
• "data" has three parts:
  • Method ID: 70a08231 - This is the 4-byte function selector for ABI balanceOf(address).
  • Padding: "000000000000000000000000"
  • Wallet Address: CD531Ae9EFCCE479654c4926dec5F6209531Ca7b - The address to query the balance for, padded to 32 bytes (64 characters) CD531Ae9EFCCE479654c4926dec5F6209531Ca7b
  • The full data field will be: "0x70a08231" + "000000000000000000000000" + "CD531Ae9EFCCE479654c4926dec5F6209531Ca7b"

curl --location 'https://api.tatum.io/v3/blockchain/node/ethereum-mainnet/' \
--header 'Content-Type: application/json' \
--header 'x-api-key: {YOUR_API_KEY}' \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_call",
    "params":[
      {
        "to": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
        "data": "0x70a08231000000000000000000000000CD531Ae9EFCCE479654c4926dec5F6209531Ca7b"
      },
      "latest"
    ],
    "id":1
  }'
//response:
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": "0x0000000000000000000000000000000000000000000000000000000000f4240"
}

Step_4: Interpret and convert the response.

Example request:

1. The "result" field is the balance in hexadecimal (Wei).
2. Convert the result in hex to decimal and adjust for the token's decimals (USDC uses 6 decimals).

# Example response balance in hexadecimal
balance_hex = "0x0000000000000000000000000000000000000000000000000000000000f4240"

# Convert hexadecimal to integer
balance_wei = int(balance_hex, 16)

# USDC uses 6 decimals
decimals = 6

# Convert to human-readable format
balance_human_readable = balance_wei / (10 ** decimals)

print(balance_human_readable)

TRC-20 (Tron)

Steps

Step_1: Fetch the Smart Contract Address

1. For example USDT over Tron: TR7NHqjeKQxGTCi8q8ZY4pL8otSzgjLj6t
2. Convert the Address in hexadecimal format. You may use an online service.
3. Address converted: 0xa614f803B6FD780986A42c78Ec9c7f77e6DeD13C

Step_2: Fetch the Wallet Address

1. For example TJDENsfBJs4RFETt1X1W8wMDc8M5XnJhCe
2. Convert the Address in hexadecimal format. You may use an online service.
3. Exclude the 0x --> 415a67fa7cc56bd6d043a98e17d329c1dc9e14753f

Step_3: Make an RPC call with the method eth_call

Example request:

• "to" is the ContractAddress for USDT (converted) 0xa614f803B6FD780986A42c78Ec9c7f77e6DeD13C
• "data" has three parts:
  • Method ID: 70a08231 - This is the 4-byte function selector for ABI balanceOf(address).
  • Padding: "000000000000000000000000"
  • Wallet Address: 415a67fa7cc56bd6d043a98e17d329c1dc9e14753f - The address to query the balance for, padded to 32 bytes (64 characters) 415a67fa7cc56bd6d043a98e17d329c1dc9e14753f
  • The full data field will be: "0x70a08231" + "000000000000000000000000" + "415a67fa7cc56bd6d043a98e17d329c1dc9e14753f"

curl --location 'https://api.tatum.io/v3/blockchain/node/tron-mainnet/jsonrpc' \
--header 'Content-Type: application/json' \
--header 'x-api-key: {YOUR_API_KEY}' \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_call",
    "params":[
        {
            "to": "0xa614f803B6FD780986A42c78Ec9c7f77e6DeD13C",
            "data": "0x70a082310000000000000000000000415a67fa7cc56bd6d043a98e17d329c1dc9e14753f"
        },
        "latest"
    ],
    "id":1
}'
//response:
{
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x00000000000000000000000000000000000000000000000000003444b797a568"
}

Step_4: Interpret and convert the response.

Example request:

1. The "result" field is the balance in hexadecimal (Wei).
2. Convert the result in hex to decimal and adjust for the token's decimals (USDT uses 6 decimals).

# Example response balance in hexadecimal
balance_hex = "0x0000000000000000000000000000000000000000000000000000000000f4240"

# Convert hexadecimal to integer
balance_wei = int(balance_hex, 16)

# USDC uses 6 decimals
decimals = 6

# Convert to human-readable format
balance_human_readable = balance_wei / (10 ** decimals)

print(balance_human_readable)

Good to know

• Depending on the Smart Contract code, the method to fetch the balance may vary.
• Tatum staff generally does not troubleshoot RPC requests, unless there's an error explicitly related to our infrastructure.