TL;DR

Bitcoin Core is the open-source software that runs the Bitcoin network, validating transactions and blocks.
Maintained by a global community of developers through a consensus-driven, decentralized governance model.
Bitcoin Core powers Bitcoin by checking transactions. A new rule allowing more data led to mixed reactions from developers and users.
Bitcoin Core maintains the fairness and security of Bitcoin. A recent update sparked debate about striking a balance between innovation and decentralization.

Introduction

Bitcoin is a decentralized digital ledger recording transactions without a central authority. Bitcoin Core, the software that powers the network, ensures secure and decentralized transactions. It’s the system’s backbone, preventing cheating. Recent debates over changes to Bitcoin Core’s relay policy have raised questions about the network’s future.

In this article, we’ll dive into what Bitcoin Core is, how it powers the Bitcoin network, who’s behind it, and why the recent controversy matters. By the end, you’ll see why Bitcoin Core is so vital and how you can get involved.

What is Bitcoin Core?

Bitcoin Core is the original software that runs the Bitcoin network (Bitcoin.org, 2025). Think of it as the rulebook and referee rolled into one. It’s open-source, meaning anyone can look at the code, suggest changes, or use it to run their own Bitcoin node. A “full node” is a computer running Bitcoin Core that checks every transaction and block to make sure they follow Bitcoin’s rules. This validation process is crucial—it prevents fake transactions and maintains the network's integrity.

Bitcoin Core does more than just check transactions. It includes a wallet for storing and sending Bitcoin, allows users to broadcast transactions to the network, and can be used in conjunction with Lightning Network software for faster, cheaper payments. Running a full node isn’t just for tech wizards—it’s a way for anyone to help keep Bitcoin decentralized. The more people run nodes, the harder it is for any single group to control the network.

The story of Bitcoin Core starts with Satoshi Nakamoto, Bitcoin’s mysterious creator, who released the first version in 2009. Since then, it’s been the go-to software for Bitcoin, evolving through community contributions. It’s not just code—it’s the foundation of a system designed to be free from central control.

How Bitcoin Core Powers the Network?

Bitcoin Core is like the glue that holds the Bitcoin network together. Here’s how it works:

Transaction Validation and Block Propagation: When you send Bitcoin, your transaction gets broadcast to the network. Full nodes running Bitcoin Core check if it’s valid—does the sender have enough Bitcoin? Is the transaction formatted correctly? If it passes, the node passes it along to others.
Nodes also verify blocks (groups of transactions) created by miners, ensuring they follow Bitcoin’s rules. This process, known as block propagation, ensures the network remains in sync.
Maintaining Consensus Rules: Bitcoin Core enforces the rules that everyone agrees on, such as the 21 million Bitcoin cap or the structure of transactions. These rules prevent chaos, ensuring all nodes see the identical blockchain. If someone tries to break the rules (say, by spending the same Bitcoin twice), nodes reject it.
Preventing Double-Spending: By validating transactions, Bitcoin Core ensures no one can spend the same Bitcoin twice. It’s like a cashier checking your money isn’t counterfeit before accepting it.
Decentralization and Security: Every full node strengthens Bitcoin’s decentralized nature. If a hacker attacks one node, thousands of others keep the network running. For example, if you run Bitcoin Core on your computer, you’re helping verify transactions independently, making the system more resilient.

Governance and Development of Bitcoin Core

A single company or person doesn’t control Bitcoin Core—it’s a community effort. Developers from around the world volunteer their time to improve the software. They fix bugs, add features, and propose changes through Bitcoin Improvement Proposals (BIPs). A BIP is like a suggestion box for Bitcoin—anyone can submit one, but it must convince the community to be adopted.

Decisions regarding Bitcoin Core are made through consensus. Developers discuss ideas on platforms like GitHub and forums like BitcoinTalk. For a change to go through, most nodes must agree to run the updated software. This process is slow but deliberate, ensuring no one can force unwanted changes. It’s a bit like a town hall meeting—everyone gets a say, and the best ideas win through reason and debate.

Transparency is key. All code changes are public on GitHub, and anyone can review or comment on them. This openness fosters trust, as no one can sneak in malicious code without being scrutinized. The community’s collaboration ensures Bitcoin Core stays true to Bitcoin’s goal of being a decentralized, secure currency.

Recent Controversy: Bitcoin Core Relay Policy Changes

On June 7, 2025, Bitcoin Core developers announced a new relay policy, sparking a significant reaction within the community. The policy allows nodes more freedom to choose which transactions to relay. One crucial change was increasing the OP_RETURN byte limit from 80 to 160 bytes to support projects like BitVM, which aims to bring smart contracts to Bitcoin. OP_RETURN allows users to attach small pieces of data to transactions, such as notes or digital records.

Historically, it was capped to prevent abuse, but the May 8, 2025, network upgrade removed some data limits, and the new policy doubled the OP_RETURN cap. This change follows a broader trend, as the Bitcoin Core development team announced that the upcoming Core 30 release in October will further increase the OP_RETURN data carrier limit to nearly 4MB. This decision, driven by a reformist segment of the development community, marks a shift in striking a balance between innovation and efficiency.

Critics argue that prioritizing data-heavy transactions could result in increased transaction fees and slower confirmation times. There are also concerns about centralization if large nodes or mining pools start filtering or prioritizing specific types of transactions. Despite this, supporters of the change view it as a step toward a more flexible and censorship-resistant network architecture that empowers developers and users.

Conclusion

Bitcoin Core secures and decentralizes the Bitcoin network. Its open-source, community-driven model fosters transparency and trust. The relay policy debate, involving OP_RETURN and network health, highlights the community’s ongoing efforts to find the right balance between flexibility and efficiency.

As Bitcoin continues to evolve, its future will be shaped by its users and developers. To get involved, you can download Bitcoin Core, run a node, or join discussions on GitHub or official forums. Whether you’re concerned about data limits or excited about new capabilities, your participation helps ensure Bitcoin remains resilient, decentralized, and innovative.

References

Bitcoin.org. (2025). Bitcoin Core. Retrieved from https://bitcoin.org/en/bitcoin-core/

What Is Bitcoin Core: How the Software Powers Bitcoin and Why It's Sparking Debate Recently