Gochain is a minimal blockchain implementation written in Go.
It shows how blocks, transactions, and validation work under the hood in a blockchain system.

• Create and add blocks via HTTP endpoints
• SHA-256 hashing for block integrity
• Simple transaction model (sender, receiver, amount)
• Block validation and chain consistency checks
• Genesis block automatically generated on startup
• Clean modular Go code architecture
• RESTful HTTP API

Returns the entire blockchain in JSON format.

curl http://localhost:8080/

[
  {
    "Index": 0,
    "Timestamp": "2025-10-14 21:00:00.123456789 +0000 UTC",
    "Transactions": [
      {
        "Sender": "Amer",
        "Receiver": "Ahmed",
        "Amount": 50,
        "Timestamp": "2025-10-14T21:00:00Z"
      }
    ],
    "Hash": "c8fda9b2e1f3a4d5c6b7e8f9a0b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9",
    "PrevHash": ""
  }
]

Adds a new block containing one or more transactions.

{
    "Transactions": [
    {
        "Sender": "Muhammed",
        "Receiver": "Ali",
        "Amount": 100,
        "Timestamp": "2025-10-14T21:00:00Z"
    }
    ],
}

Each block contains:

• Index: Position in the blockchain (starting at 0)
• Timestamp: When the block was created
• Transactions: Array of transactions included in the block
• Hash: SHA-256 hash of the block's contents
• PrevHash: Hash of the previous block (linking the chain)

The hash is calculated from:

Hash = SHA256(Index + Timestamp + Transactions + PrevHash)

This ensures that any tampering with block data changes the hash, breaking the chain.

A new block is valid if:

• Its index is exactly one more than the previous block
• Its PrevHash matches the previous block's Hash
• Its Hash is correctly calculated from its contents

If a longer valid chain is received, it replaces the current chain.

1. Clone the repository:

git clone https://github.com/iamAmer/gochain.git
cd gochain

2. Install dependencies:

go mod tidy

This command downloads all required packages and cleans up your dependency list.

3. Create a .env file:

echo "PORT=8080" > .env

4. Run the blockchain:

go run .

The server will start on http://localhost:8080 (or the port specified in your .env file).

MIT License - feel free to use this for learning and experimentation!