# Query Blocks

> Query Ethereum blocks, transactions, receipts, balances, and nonces using Nethereum (.NET). Use this skill whenever the user asks about getting block data, reading transactions, checking balances, fetching receipts, getting nonces, querying on-chain state, decoding event logs from receipts, detecting contracts, or reading ERC20 token balances with C# or .NET.

- Skill: `nethereum/query-blocks` (Agent Skill)
- Install (CLI): `npx skillmds@latest add nethereum/query-blocks`
- Raw SKILL.md: https://api.skillmd.com/api/skills/nethereum/query-blocks/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: nethereum (https://skillmd.com/u/nethereum)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/nethereum/query-blocks

---


# Query Blocks and Transactions

NuGet: `Nethereum.Web3`

All operations here are read-only — no private key needed.

## Connect

```csharp
using Nethereum.Web3;

var web3 = new Web3("https://mainnet.infura.io/v3/YOUR_KEY");
```

## Account Balance

```csharp
var balance = await web3.Eth.GetBalance.SendRequestAsync("0xaddress...");
var etherAmount = Nethereum.Util.UnitConversion.Convert.FromWei(balance.Value);
```

## Balance at Specific Block

```csharp
using Nethereum.RPC.Eth.DTOs;

var balance = await web3.Eth.GetBalance.SendRequestAsync(
    "0xaddress...",
    new BlockParameter(new HexBigInteger(15000000)));
```

`BlockParameter` also accepts `BlockParameter.CreateLatest()`, `CreatePending()`, `CreateEarliest()`.

## Block Number

```csharp
var blockNumber = await web3.Eth.Blocks.GetBlockNumber.SendRequestAsync();
```

## Block with Transactions

```csharp
using Nethereum.Hex.HexTypes;

var block = await web3.Eth.Blocks.GetBlockWithTransactionsByNumber
    .SendRequestAsync(new HexBigInteger(blockNumber));
// block.Number, block.Timestamp, block.Transactions[]
// block.BaseFee (present on EIP-1559 blocks)
```

For tx hashes only (lighter): `GetBlockWithTransactionsHashesByNumber`.

## Block by Hash

```csharp
var block = await web3.Eth.Blocks.GetBlockWithTransactionsByHash
    .SendRequestAsync("0xabc123...");
```

## Transaction by Hash

Returns the transaction as submitted (before execution):

```csharp
var tx = await web3.Eth.Transactions.GetTransactionByHash
    .SendRequestAsync("0xtxhash...");
// tx.From, tx.To, tx.Value, tx.GasPrice
// tx.MaxFeePerGas, tx.MaxPriorityFeePerGas (EIP-1559)
// tx.Type (0x0 = legacy, 0x2 = EIP-1559)
```

## Transaction Receipt

Available after mining. Shows success/failure, gas used, and events:

```csharp
var receipt = await web3.Eth.Transactions.GetTransactionReceipt
    .SendRequestAsync("0xtxhash...");
// receipt.Status (1 = success, 0 = revert)
// receipt.GasUsed, receipt.EffectiveGasPrice
// receipt.Logs, receipt.BlockNumber
```

Both `GetTransactionByHash` and `GetTransactionReceipt` return `null` for unconfirmed transactions.

## Transaction Count (Nonce)

```csharp
var nonce = await web3.Eth.Transactions.GetTransactionCount
    .SendRequestAsync("0xaddress...");
```

## Contract Detection

```csharp
var code = await web3.Eth.GetCode.SendRequestAsync("0xaddress...");
// Returns "0x" for EOAs, bytecode for contracts
var isContract = code != null && code != "0x";
```

## Decode Events from Receipt

```csharp
using Nethereum.Contracts;
using Nethereum.Contracts.Standards.ERC20.ContractDefinition;

var receipt = await web3.Eth.Transactions.GetTransactionReceipt
    .SendRequestAsync("0x654288d8...");

var events = receipt.DecodeAllEvents<TransferEventDTO>();
Console.WriteLine($"From: {events[0].Event.From}");
Console.WriteLine($"To: {events[0].Event.To}");
Console.WriteLine($"Value: {events[0].Event.Value}");
```

`DecodeAllEvents<T>()` scans all logs and returns only those matching the event signature.

## ERC20 Balance via Typed Service

```csharp
var tokenBalance = await web3.Eth.ERC20
    .GetContractService("0x9f8f72aa9304c8b593d555f12ef6589cc3a579a2")
    .BalanceOfQueryAsync("0x8ee7d9235e01e6b42345120b5d270bdb763624c7");
Console.WriteLine(Web3.Convert.FromWei(tokenBalance, 18));
```

## Check If Transaction Succeeded

```csharp
var receipt = await web3.Eth.Transactions.GetTransactionReceipt
    .SendRequestAsync(txHash);

if (receipt == null)
    Console.WriteLine("Transaction not yet mined");
else if (receipt.Status.Value == 1)
    Console.WriteLine("Success");
else
    Console.WriteLine("Reverted");
```

## Calculate Transaction Cost in ETH

```csharp
var costWei = receipt.GasUsed.Value * receipt.EffectiveGasPrice.Value;
var costEth = Nethereum.Util.UnitConversion.Convert.FromWei(costWei);
```