Transaction Decoder

Decode any Bitcoin transaction into a human-readable analysis: inputs, outputs, script types, fee rate, SegWit savings, and inscription detection.

Usage

python tx_decoder.py <txid>

# Example: decode the genesis coinbase
python tx_decoder.py 4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b

What It Shows

• Transaction version, size, vsize, weight
• Each input: previous txid, vout, script type
• Each output: value (BTC + sats), script type, address
• Fee in satoshis and fee rate in sat/vB
• SegWit discount percentage (how much the sender saved)
• Whether the transaction contains an Ordinals inscription

How It Works

1. Calls getrawtransaction(txid, 2) to get the fully decoded transaction
2. Parses each input’s scriptSig and witness to identify the script type
3. Parses each output’s scriptPubKey to identify the address type
4. Computes fee = sum(input values) - sum(output values)
5. Scans witness data for the Ordinals inscription marker (ord)

Requires txindex=1 in your bitcoin.conf to decode arbitrary transactions (not just those in your wallet).

Protocol Context

This tool demonstrates the core concepts from Chapter 1 (UTXOs) and Chapter 2 (Script) in action. Every transaction consumes UTXOs (inputs) and creates new ones (outputs). The script types visible in the output show the evolution of Bitcoin’s address formats:

• pubkeyhash = P2PKH (1… addresses, 2009)
• scripthash = P2SH (3… addresses, 2012)
• witness_v0_keyhash = P2WPKH (bc1q…, 2017 SegWit)
• witness_v1_taproot = P2TR (bc1p…, 2021 Taproot)

The inscription detection shows how Ordinals embed data in the witness field using the OP_FALSE OP_IF envelope — see Chapter 5.