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Build Your Own Transaction

A hands-on developer course: construct a Bitcoin transaction from raw bytes — selecting inputs, building outputs, serializing, signing, and broadcasting.

10steps · ~ 90min

Progress 0/10

This advanced developer course takes you through the process of building a raw Bitcoin transaction from scratch. You’ll learn how UTXOs work, construct inputs and outputs, calculate fees, serialize the transaction into hex bytes, sign it with your private key, and broadcast it to the network.

Prerequisites: familiarity with Bitcoin basics and comfort with technical concepts.

1

Overview

What you'll build: a valid, broadcastable Bitcoin transaction, field by field.

2

Understanding UTXOs

How Bitcoin tracks ownership without account balances.

3

Constructing Inputs

Selecting and referencing unspent outputs to spend.

4

Constructing Outputs

Creating new outputs for the recipient and your change.

5

Calculating Fees

How miners prioritize transactions and how to set the right fee.

6

Raw Serialization

Converting transaction data into the hex byte format the network expects.

7

Signing the Transaction

Using your private key to authorize the spend.

8

SegWit and Witness Data

How Segregated Witness separates signatures and expands block capacity.

9

Broadcasting

Pushing your signed transaction onto the Bitcoin network.

10

Verifying and Exploring

Confirming your transaction on the blockchain and understanding every byte.

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