Bitcoin Core recorded a clear increase in development activity during 2025, reversing a multi-year slowdown.
Casa chief security officer Jameson Lopp said developer engagement strengthened across multiple metrics.
Email traffic on the Bitcoin Development Mailing List rose 60% compared with 2024.
The increase followed a 25% decline the previous year linked to the mailing list’s platform migration.
Lopp reported that 135 unique contributors submitted code to Bitcoin Core in 2025.
The contributor count rose from about 112 in 2024, ending several years of decline.
Bitcoin Core contributor numbers had previously peaked near 193 developers in 2018.
Total code changes reached roughly 285,000 lines added and removed during the year.
The volume of code activity remained broadly consistent with Bitcoin Core’s long-term historical pace.
Bitcoin Core completed its first public third-party security audit in November.
The audit, conducted by Quarkslab and funded by Brink, found no critical vulnerabilities.
Developers also debated mempool policy changes during the year.
A controversial update removing OP_RETURN data limits was merged into the v30 release.
Funding support continued, with VanEck maintaining its commitment to donate ETF profits to Bitcoin development.
At the time of reporting, Bitcoin price was $92,823.89.