Segregated witness (SegWit): How Bitcoin addressed scaling and transaction malleability

Segregated Witness (SegWit) activated on the Bitcoin network in August 2017 as a soft fork upgrade that addressed two critical limitations: network congestion and transaction malleability.

By separating signature data from transaction data, SegWit increased block capacity and enabled the development of second-layer solutions like the Lightning Network without requiring a disruptive hard fork.

What Is SegWit and Why It matters

Segregated Witness (SegWit) was developed by Pieter Wuille and proposed through Bitcoin Improvement Proposal 141 (BIP141), SegWit fundamentally changed how transaction data is stored on the blockchain.

SegWit separates or segregate signature data, known as witness data from the main transaction block.

This restructuring allows more transactions to fit into each block without increasing the official block size limit of 1MB.

For crypto investors, SegWit marked a turning point. It improved transaction throughput, reduced fees, and laid the foundation for second-layer solutions like the Lightning Network.

How SegWit Works Under The Hood

Before SegWit, every Bitcoin transaction included both transaction data and signature data in the same block space. Signature data can account for up to 65% of a transaction’s size, making blocks inefficient.

SegWit introduced a new structure; Transaction data remains in the main block, and signature (witness) data is stored separately,

This effectively increases block capacity to about 4MB in weight units, without a hard fork. Importantly, SegWit was implemented as a soft fork, meaning it remained backward-compatible with older nodes.

According to the Bitcoin Core documentation, this innovation increases block capacity and fixes transaction malleability, enabling more advanced scripting capabilities.

The problem SegWit solved: scaling and malleability

Before 2017, Bitcoin faced two major challenges which are;

1. Network congestion

As adoption grew, transaction volume surged, leading to slower confirmation times and higher fees.

Investors often paid significant fees just to get transactions processed quickly.

2. Transaction malleability

This technical flaw allowed transaction IDs to be altered before confirmation, creating uncertainty for developers and limiting the development of advanced solutions.

However, SegWit directly addressed both issues. By removing signature data from the transaction hash, it eliminated malleability risks, making the network more reliable for building additional layers.

Impact on fees, speed, and adoption

Since its activation, SegWit adoption has steadily increased across wallets and exchanges.

Platforms like Coinbase and Binance integrated SegWit addresses, helping reduce transaction costs for users.

Key benefits include:

• Lower transaction fees: More transactions per block means reduced competition for space.
• Faster confirmations: Improved efficiency reduces backlog during high demand.
• Better scalability: Opens the door for Layer 2 technologies.

Data from blockchain analytics firm Glassnode shows that SegWit usage now accounts for a significant share of Bitcoin transactions, contributing to improved network performance.

Why SegWit still matters for investors

For crypto investors, SegWit is more than a technical upgrade it’s a foundational improvement that strengthened Bitcoin’s long-term viability. It enabled;

• The rise of the Lightning Network for instant, low-cost payments,
• Increased institutional confidence in Bitcoin’s scalability
• A pathway for future upgrades without disruptive hard forks

While newer scaling debates continue, such as those involving block size or alternative chains, SegWit remains a key milestone in Bitcoin’s evolution.