peek

A simple command-line program to peek into real-time unconfirmed Bitcoin transactions using Blockchain.com's Bitcoin WebSocket API.

WIP!

Prerequisites

• Python >= 3.6

Cloning & Running

git clone https://github.com/qlyde/peek.git
cd peek/
pip3 install -r requirements.txt
python3 peek.py

Options

• -h, --help display a help message and exit
• -m dollars, --min-val dollars only peek at transactions above a minimum total output (default to $0)
• -t seconds, --time seconds keep websocket open for specified time (default to 10 seconds)
• -o, --overflow let table print past terminal height (not recommended)

If column overflow is enabled, enlarge your terminal window. This option is not recommended as it can cause buggy output after scrolling up (ie. some transactions get printed multiple times).

Demo

API Reference

See the Blockchain API for more info. No authentication is needed to access the Explorer - Transactions & Blocks Bitcoin WebSocket API.

Overview

From Satoshi Nakamoto's Bitcoin Whitepaper,

We define an electronic coin as a chain of digital signatures. Each owner transfers the coin to the next by digitally signing a hash of the previous transaction and the public key of the next owner and adding these to the end of the coin. A payee can verify the signatures to verify the chain of ownership.

Blockchain

A block in the chain contains many transactions. Pairs of transaction IDs (TXIDs) are hashed and pairs of hashes are hashed again, and again, until a single hash remains - the merkle root, which is stored in a block's header.

Each block also stores a hash of the previous block's header, creating a chain. This enforces immutable transactions.

Transactions

A transaction consists of one or more inputs and one or more outputs. When you spend your coins, you are actually spending an unspent transaction output (UTXO) that you own. An output is considered unspent if it is not referenced as an input for any other transaction. Your "wallet balance" is actually determined by your UTXOs and your unconfirmed transactions in the mempool.

There is no way to split a UTXO, so if you have a 5 BTC UTXO and want to spend 2 BTC, then you actually spend all 5 BTCs and two new UTXOs are created - one worth 2 BTC which is paid to the receiver, and one worth 3 BTC which is paid back to you as change. This is why there are often two or more to_addr for one transaction in peek.

Coinbase transactions are an exception to some of these rules. A coinbase is a mining reward whereby miners receive Bitcoin as a reward for mining. Mining is simply a process where miners verify the legitimacy of a transaction. The first transaction in each block is the coinbase transaction.

More

Blockchain.com supports blockchain exploring and can be used to view certain blocks, transactions and more.

To view more details of a specific transaction, copy its hash and go to blockchain.com/btc/tx/<hash>. eg. for a hash=5f278439303d87f7324543a3e873ffd01a18b45bd61476d223341667007680e1 go to https://www.blockchain.com/btc/tx/5f278439303d87f7324543a3e873ffd01a18b45bd61476d223341667007680e1

TODO

• Add option to only print n transactions
• Add option to keep alive for n seconds
• Add option to filter for transactions over $N
• Add option to let table overflow
• Add colour to indicate transaction size
• Add support for currencies other than est_aud