Bitcoin Core Development Rebounds: 135 Developers Drive Protocol Growth in 2025

Source: Btcpeers Original Title: Bitcoin Network Activity Rebounds as Developer Count Jumps Original Link: Bitcoin Core development activity increased in 2025 as 135 developers contributed code to the software. This represents growth from approximately 112 contributors in 2024. Jameson Lopp, co-founder of crypto management platform Casa, published the annual metrics on January 5, 2026.

The developers changed 285,000 lines of code during 2025. This marks a three percent increase from the 276,000 lines modified in 2024. Code commits to Bitcoin Core rose one percent to 2,541 for the year. Email volume to the Bitcoin Development Mailing List jumped 60 percent compared to 2024. The mailing list serves as a communication hub for proposing and debating network changes.

Reversing a Multi-Year Decline

The growth reverses a downward trend that began after 2018. Bitcoin Core contributor counts peaked near 200 developers in 2018 before declining through the early 2020s. The 2025 rebound demonstrates renewed interest in Bitcoin protocol development. Bitcoin Core remains the reference implementation that powers approximately 78 percent of Bitcoin full nodes.

The software completed its first public third-party security audit in November 2025. Cybersecurity firm Quarkslab conducted the audit with funding from nonprofit Brink. The audit found no critical or high-severity vulnerabilities in Bitcoin Core’s peer-to-peer networking layer. The year also included debates over mempool policy changes. A controversial update to OP_RETURN limits was merged in the version 30 release. The change removed the 83-byte cap on data that can be embedded in transactions.

Institutional Adoption Drives Development Focus

Bitcoin Core development activity increased alongside growing institutional adoption of Bitcoin. The United States established a Strategic Bitcoin Reserve in March 2025 through an executive order. The policy centralized government-held Bitcoin obtained through civil and criminal forfeiture. The assets are prohibited from sale under the reserve framework.

Bitcoin reached a peak price above $126,000 on a certain compliance platform in October 2025. Major financial institutions increased their cryptocurrency exposure. Spot Bitcoin exchange-traded funds facilitated institutional access. BlackRock’s iShares Bitcoin Trust ETF accumulated over $50 billion in assets.

Organizations supporting Bitcoin Core development continued funding efforts throughout 2025. VanEck maintained its commitment of five percent of spot Bitcoin ETF profits to developer nonprofit Brink. The sustained funding helps ensure developers have resources for ongoing protocol improvements. Development activity may continue rising as Bitcoin integrates into traditional financial systems.