How to Build a Blockchain from Scratch with Go

Introduction

Web 3.0 and blockchain technology are revolutionizing industries, but do you truly understand how blockchain works under the hood? This tutorial will guide you through building a blockchain from scratch using Go, offering hands-on experience with this transformative technology.

By the end, you’ll:

• Set up a Go project without prior GoLang experience.
• Generate and distribute your first blockchain tokens.
• Develop a CLI-controlled database in Go.
• Discover blockchain’s core value propositions.
• Make your database immutable using cryptographic hashing.

⭐ Meet Andrej: The Protagonist

Andrej is a Slovakian bar owner and software developer tired of traditional payment systems. His vision? A decentralized, blockchain-powered bar where customers use TBB (The Blockchain Bar tokens) for transactions, earning shareholder rights in the process.

Goals:

• Auditable transaction history for tax compliance.
• Autonomous, decentralized payments eliminating cash handling.
• Customer governance via token-based voting on bar operations.

Table of Contents

1. Requirements
2. Project Setup
3. 01 | The MVP Database
4. 02 | Mutating Global DB State
5. 03 | Monolithic Event vs Transaction
6. 04 | Humans Are Greedy
7. 05 | Why We Need Blockchain
8. 06 | Immutable Hashing
9. Next Steps

Requirements

• Programming Experience: 2+ years in Java/PHP/JavaScript or similar.
• Go Basics: Complete A Tour of Go (~20 mins).

Why Go?

• High performance with multi-core optimization.
• Lightweight concurrency (goroutines).
• Portable binary compilation.

Setup the Project

Clone the GitHub repository and follow the installation instructions.

👉 Get the Full Code Here

01 | The MVP Database

Start with a simple JSON-based database:

Genesis File (genesis.json):

{
  "genesis_time": "2019-03-18T00:00:00.000000000Z",
  "chain_id": "the-blockchain-bar-ledger",
  "balances": { "andrej": 1000000 }
}

Transaction Workflow:

1. Initial State: Andrej holds 1M TBB tokens.
2. Transactions: Recorded in tx.db (e.g., {"from":"andrej","to":"babayaga","value":2000}).
3. State Updates: Replayed to compute balances.

02 | Mutating Global DB State

Transactions modify the database state:

tbb tx add --from=andrej --to=babayaga --value=2000  # Transfer tokens  
tbb balances list                                    # Check balances  

Key Insight:

• Transactions (TX) are immutable events.
• Genesis balances remain static.

03 | Monolithic Event vs Transaction

Andrej refactors the system:

• Accounts: Represented as type Account string.
• Transactions: Structured with from, to, value, and data fields.
• CLI: Built using Cobra for adding TXs and listing balances.

type Tx struct {
  From  Account `json:"from"`
  To    Account `json:"to"`
  Value uint    `json:"value"`
  Data  string  `json:"data"`  // e.g., "reward"
}

04 | Humans Are Greedy

Real-World Conflict:

• BabaYaga disputes a hidden 50 TBB fee.
• Highlights the need for transparency and decentralization.

05 | Why We Need Blockchain

Problems with Centralization:

• Hidden fees.
• Data tampering risks.
• Slow, opaque transactions.

Blockchain Solutions:

• Immutable, auditable records.
• Decentralized governance.

06 | Immutable Hashing

Cryptographic Hashing (sha256):

snapshot := sha256.Sum256(txsData)  // Unique fingerprint for DB state  

How It Works:

1. Hash the entire tx.db file.
2. Use the hash (7d4a360f...) to reference specific states.

Try It:

tbb balances list  # Verify balances match the snapshot hash  

Next Steps

Continue to Chapter 07:

• Batch transactions into blocks.
• Migrate from tx.db to blocks.db.

👉 Explore the Full Tutorial

FAQs

1. Is blockchain just a database?

Yes, but immutable and decentralized. Transactions are cryptographically secured.

2. Why use Go for blockchain?

Performance, concurrency, and portability make Go ideal for distributed systems.

3. How are tokens created?

Defined in the genesis.json file and distributed via transactions.

By building this project, you’ve taken the first step toward mastering blockchain development. Stay tuned for advanced concepts! 🚀

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