Bitcoin Core Development Soars 60% After Years of Decline

In 2025, development activity for Bitcoin Core surged by an impressive 60%, as evidenced by email exchanges on the Bitcoin Development Mailing List. This marks a significant turnaround from previous years of dwindling contributions, making it the most active period in the protocol's history since its inception. With contributions from 135 developers totaling 285,000 lines of code, Bitcoin's network reflected notable growth and resilience against its fluctuating price.

Key Takeaways

Record Development Activity: Bitcoin Core's development increased by 60% in 2025, reversing a declining trend.
Strong Participation: 135 developers were involved, contributing substantial code changes—285,000 lines in total.
Value Transfer: Bitcoin processed $4.5 trillion in transactions, averaging $144,000 per second.
Network Stability: Despite a steady price, the blockchain's size and network metrics improved.
Growing Adoption: Merchant adoption rose by 53% in 2025, driven by innovations like Bitcoin payments at point-of-sale.
Security and Controversy: Major upgrades and security audits sparked discussions around Bitcoin's future direction.

2025: A Year of Growth for Bitcoin Core Development

In 2025, Bitcoin Core's development activities experienced a remarkable 60% surge compared to previous years, as indicated by the email traffic on the Bitcoin Development Mailing List. This upswing marks a significant shift from the decline in contributions observed in recent times, establishing 2025 as the protocol's most active development year since its inception.

Bitcoin Core Development Surges 60%

Core contributor Jameson Lopp noted that the increase comprised contributions from 135 different developers, who collectively made over 285,000 changes to the codebase. During this time, Bitcoin transacted an impressive $4.5 trillion in total value, averaging approximately $144,000 every second, according to estimates from CoinMetrics.

Bitcoin Core Development - Bitcoin-dev Mailing List Messages Chart

The renewed development activity emerged amidst ongoing philosophical debates about Bitcoin’s primary purpose, with several competing proposals aimed at addressing the issue of blockchain spam.

On the trading front, Bitcoin's price rebounded above $92,000 after a geopolitical surprise in Venezuela, with institutional investments flowing back into the crypto markets, as evident by $646 million in exchange-traded funds (ETFs) on the first trading day of 2026.

Network Metrics: Indications of Maturation

In 2025, Bitcoin recorded one of its most stable years, with an average daily price change of merely -0.02%. The blockchain also saw a growth in size, expanding from 626.5 GB to 710.1 GB—a 13.3% growth rate.

Bitcoin Core Development - Bitcoin Average Daily % Value Change Chart

Interestingly, the network's unspent transaction output (UTXO) set actually contracted, decreasing from 186.3 million to 165.8 million entries, indicative of efficiency enhancements as one net UTXO was removed every 1.5 seconds. The network's hashrate rose by 32%, climbing from 802 to 1,060 exahash per second, while the number of reachable nodes increased by 18%, reaching 24,298, according to Bitnodes data.

The average bandwidth for these reachable nodes also fell by 39% to 6.6 megabits per second. Code commits to Bitcoin Core only increased by 1% year-over-year, totaling 2,541, which suggests a more concentrated effort per commit.

Lopp raised alarms about trends in physical security, predicting a rise in violent theft attempts targeting Bitcoin holders, stating, “At the beginning of 2025, I predicted an all-time high for wrench attacks, averaging one per week. Unfortunately, that prediction came true.”

Adoption and Data Storage Discussions Heat Up

Merchant adoption witnessed a 53% increase in 2025, likely facilitated by Square integrating Bitcoin payments into its point-of-sale systems. Corporations also reached record highs in Bitcoin holdings, with nearly 7% of the total Bitcoin supply now held on corporate balance sheets as institutional accumulation ramped up.

Bitcoin Core Development - Known Bitcoin Held on Corporate Balance Sheets Chart

Nonetheless, Bitcoin OP_RETURN outputs fell by 47% year-over-year, attributed to a waning interest in the Runes protocol launched in 2024.

Bitcoin Core Development - OP_RETURN Transactions Outputs Created Chart

Despite this decrease, a total of 33 million inscriptions were recorded on the blockchain in 2025, reflecting a 58% increase from the previous year. However, the fees for these inscriptions were remarkably low, amounting to a total of only $12 million.

The BSV fork suffered a further decline of 64% against Bitcoin over 2025, now valued at only 0.02% of the original protocol’s worth. Meanwhile, interest in the Lightning Network surged, with its capacity reaching an all-time high of 5,805 BTC, after experiencing a decline for most of the year.

2025: A Milestone for Security Audits and Upgrade Controversies

A major highlight for Bitcoin Core in 2025 was the completion of its first public third-party security audit in 16 years, conducted by Quarkslab. The audit—which consisted of a comprehensive 100-man-day evaluation—reported no critical vulnerabilities, identifying just two low-severity issues in the peer-to-peer layer, mempool, and consensus logic.

Funded by the Open Source Technology Improvement Fund, the audit verified the integrity of the codebase at a crucial time.

In October, Bitcoin Core released version 30.0, lifting the 80-byte OP_RETURN limit and expanding the default data carrier size to 100,000 bytes, along with enabling multiple OP_RETURN outputs in a single transaction. Blockstream's CEO, Adam Back, supported this update, emphasizing that it included vital security patches from “the 200 most skilled individuals on the planet.” However, detractors raised concerns regarding potential spam and legal ramifications.

The update led to a migration toward Bitcoin Knots, an alternative implementation, which began to account for 28% of network nodes. In December, a development proposal titled “The Cat” by Claire Ostrom aimed to permanently ban Ordinal inscriptions and NFTs by marking smaller outputs as unspendable, provoking backlash from other contributors, including Greg Maxwell who labeled it as “outright theft” of substantial funds.

Bitcoin's Steady Recovery Following Geopolitical Events

As the Bitcoin ecosystem rejoices in development and growth, Akshat Siddhant, the lead quant analyst at Mudrex, remarked on the return of institutional interest following events in Venezuela.

“If BTC closes above $93,700, we could see momentum pushing it toward $100,000, with support appearing around $88,500,” he said, noting the market sentiment had shifted to neutral for the first time since October as new investments flowed into crypto ETFs.

Currently, Bitcoin is trading at $92,861, marking an increase of 1.64% in the past 24 hours.