Bitcoin developers working on the software that powers most nodes backing the blockchain had a busy year in 2025, with more developers pushing out more code, according to Bitcoiner Jameson Lopp.
Lopp, the co-founder of the crypto management platform Casa, said on Sunday that 135 different people had contributed code to Bitcoin Core last year, rising from just over 100 individuals in 2024 and continuing an uptrend. The number of contributors peaked in 2018 with nearly 200 contributors.
Those developers also changed more code, with Lopp reporting 285,000 lines of code were changed last year, a more than 3% jump from the 276,000 lines of code changed in 2024.
The jump in development activity came amid a big year for Bitcoin (BTC), which continued to set new price records and peaked at over $126,000 on Coinbase in October, as major financial institutions were keen to bet on the cryptocurrency under the crypto-friendly Trump administration.
Metrics show an uptick in developer activity
Lopp also shared that the code commits to Bitcoin Core, essentially updates to the codebase, increased by 1% over the year to 2,541, continuing an uptrend since 2023 after a decline from a peak of nearly 3,500 in 2021.
The email volume to the Bitcoin Development Mailing List, a major hub for communicating and hashing out changes to the network, also jumped 60% year over year in 2025.
However, the results are still a way off the all-time peak of around 5,000 messages in 2015.
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The metric upswing caps a big year for Bitcoin Core development activity, which included debate over the OP_RETURN data limit, which increased in October, allowing a larger amount of non-financial data to be embedded in Bitcoin transactions.
Bitcoin Core also passed its first-ever third-party security audit in November, with the security firm Quarkslab finding that the software running the blockchain was “mature and well-tested” with no high or medium-severity vulnerabilities.
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