In 2025, Bitcoin developers engaged with Bitcoin Core—the software that supports the majority of blockchain nodes—had a hectic year, as noted by Bitcoiner Jameson Lopp.
Lopp, co-founder of the crypto management platform Casa, mentioned on Sunday that 135 unique contributors added code to Bitcoin Core last year, a rise from just over 100 individuals in 2024, continuing a positive trend. The peak number of contributors was in 2018, with almost 200 involved.
The developers also modified more code, with Lopp reporting that 285,000 lines were altered last year, representing a greater than 3% increase from the 276,000 lines modified in 2024.
This surge in development activity coincided with a significant year for Bitcoin (BTC), which has been setting new price milestones, reaching over $126,000 in October, as major financial institutions favored the cryptocurrency during the crypto-friendly Trump administration.
Metrics Indicate Increased Developer Activity
Lopp also reported that the code commits to Bitcoin Core—essentially updates to the codebase—increased by 1% over the year to 2,541, continuing an upward trend since 2023, following a peak of nearly 3,500 in 2021.
The email traffic on the Bitcoin Development Mailing List, a key platform for discussing and finalizing changes to the network, also rose by 60% year-over-year in 2025.
However, these figures are still far from the all-time high of around 5,000 messages recorded in 2015.
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The increase in metrics caps a significant year for Bitcoin Core development, which included discussions regarding the OP_RETURN data limit, raised in October, allowing more non-financial data to be included in Bitcoin transactions.
Bitcoin Core also underwent its first-ever third-party security audit in November, with the security firm Quarkslab concluding that the blockchain software was “mature and well-tested” with no high or medium-severity vulnerabilities.
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