Nodes & decentralisation: who checks Bitcoin’s rules

In Bitcoin, there is no bank that checks payments for everyone. Tens of thousands of computers around the world do that job, each on its own: the nodes. They are the reason the rules can’t be changed from above – and you can run one yourself.

What a full node does

A nodeGlossaryNodeA computer that runs Bitcoin software and exchanges transactions and blocks with other nodes. Together, the nodes form the Bitcoin network; full nodes check every rule themselves.On the learning path: Stage 1 · Step 3 – How does Bitcoin work? →In the glossary →× is a computer that runs Bitcoin software and is connected to other nodes. A full nodeGlossaryFull nodeA node that checks every block and every transaction itself against all the consensus rules. If you run a full node, you don’t have to trust anyone to know whether a payment is valid.In the glossary →× keeps its own copy of the blockchain, containing only blocks it has checked itself.^[1] Among other things, it checks:

• whether every signature is valid,
• that no coin is spent twice,^[1]
• whether a block follows the rules on size, computing work and reward – and with them the cap of 21 million BTC.

In pruning mode, a node also checks the complete history but then deletes old blocks. This way, the storage for block data can be limited to 550 MB.^[10]

Role	What it does	What it can’t do
Full node	checks every block and every transaction, stores and distributes the blockchain	create new bitcoin, set rules for others
Miner	bundles transactions into blocks and performs computing work (proof of work)	make a block valid that the nodes reject
Light wallet	shows balances and sends transactions, often via someone else’s server	check all the rules itself

A block with too high a reward or a double spend is discarded, no matter how much computing work went into it.

‘Don’t trust, verify’

With a full node, you don’t have to take anyone’s word – not an exchangeTermExchange (crypto exchange)A trading platform where buyers and sellers trade bitcoin with each other via an order book.On the learning path: Stage 4 · Step 2 – Choosing a provider →In the glossary →AdLicensed providers with a paid linkProviders from our comparisonKrakenExchange · MiCA (Central Bank of Ireland)Visit Kraken* (paid link, opens in a new window)BitvavoExchange · MiCA (AFM, Netherlands)Visit Bitvavo* (paid link, opens in a new window)CoinbaseExchange · MiCA (CSSF, Luxembourg)Visit Coinbase* (paid link, opens in a new window)All 7 compared – including non-partners →*Paid link: if you sign up or buy through it, we earn a commission. Your price stays the same. How we make money →18+ · Crypto assets are highly volatile; you could lose all your money. No deposit protection.×’s, not a wallet provider’s, not even ours – for whether a payment has arrived or how many bitcoin exist. The whitepaper itself warns that simplified verification without a full node can be fooled for as long as an attacker controls the majority of the computing power.^[2]

August 2026 showed that nodes enforce the rules. From a set block onwards, nodes running the extra rules of the BIP-110 proposal rejected every block that didn’t signal support. Because hardly any miners went along, they ended up on a chain of their own, which found two blocks in around eight hours – the main chain found 48.^[3],[4] Neither miners nor a group of nodes can change the rules for everyone unilaterally; whoever deviates splits off. Background: Forks & controversies.

How decentralised is Bitcoin?

DecentralisationGlossaryDecentralisationBitcoin has no headquarters that could change the rules, freeze accounts or print more money. Instead, tens of thousands of independent nodes around the world check for themselves that all the rules are followed.On the learning path: Stage 2 · Step 3 – Criticism & risks →In the glossary →× can’t be measured with a single number. Some reference points:

> 25,000

publicly reachable nodes

Coin Dance, 28 September 2026: 25,620

≈ 83%

of them Bitcoin Core

as of 28 September 2026

≈ 17%

of them Bitcoin Knots

as of 28 September 2026

> 770 GB

size of the blockchain

as of 27 September 2026

Sources: Coin Dance and Blockchain.com.^[6],[7] Only publicly reachable nodes are counted, grouped by software – not by which chain they follow (more on that below). Many nodes behind private routers don’t accept incoming connections and are missing; there is no reliable total.

In the month to 28 September 2026, these were Foundry USA, AntPool and F2Pool.^[8] Behind a mining poolGlossaryMining poolA group of miners who combine their computing power and share the block reward according to the work each contributes. This means even small miners receive small amounts regularly instead of a large one very rarely.On the learning path: Stage 2 · Step 3 – Criticism & risks →In the glossary →×, however, are many individual miners who can switch pools. And even a large pool can only propose blocks; whether they count is decided by the nodes. More in Mining & proof of work.

Bitcoin Core and Bitcoin Knots

Most reachable nodes run the open-source software Bitcoin CoreGlossaryBitcoin CoreThe most widely used software for Bitcoin nodes, a direct descendant of Satoshi Nakamoto’s first program. It is open source, verifies all blocks and transactions itself and includes a wallet.In the glossary →×.^[6] The number two, Bitcoin Knots, builds on its code and filters more strictly against transactions that write a lot of data into the blockchain.^[9] Which software you use is your decision. One distinction matters:

• Consensus rulesGlossaryConsensus (consensus rules)The agreement of all nodes on which blocks and transactions are valid and which chain counts. It rests on fixed consensus rules that every node checks for itself – no vote, no boardroom.On the learning path: Stage 1 · Step 3 – How does Bitcoin work? →In the glossary →× define what is valid – for example the money supply or the block size. If nodes differ here, they split.
• Relay rules (policy) define which unconfirmed transactions a node passes on to others. Nodes may differ here without dividing the network.

For a long time, Core and Knots differed only in policy and formed one shared network.^[3] Since version 29.4.1 of 2 September 2026, however, Knots also changes the consensus rules: it enforces BIP-110 and a new mining algorithm (BLAKE2b), and so follows the split-off chain.^[9] No major exchange and no widely used wallet had committed in advance to supporting this chain.^[5] For the chain that exchanges, wallets and almost all miners follow, Bitcoin Core is therefore the obvious choice.

Your own node on your home network

A node doesn’t mine and doesn’t earn money; it costs a little electricity. In return, you check for yourself and reveal less about yourself to other people’s servers. What you need:

• Storage: The blockchain is over 770 GB (as of September 2026) and keeps growing.^[7] A 1 TB SSD is tight; 2 TB leaves room.
• Data volume: On first start, the node downloads the complete blockchain. After that, bitcoin.org expects around 20 GB of downloads a month; uploads can reach 200 GB or more but can be limited.^[10]
• Time: The initial sync takes several days, longer with slow hardware or a slow connection.^[10]

1. Choose the hardware

   An energy-efficient mini PC or a Raspberry Pi 4 or 5 with an external SSD is enough; RaspiBlitz, for example, is built for exactly that.^[11] An existing PC works too, in pruning mode if necessary.

2. Install the software

   Bitcoin Core directly – or a node system with a user interface such as umbrelOS (no purchase price on your own hardware, also sold by the provider as a ready-made device).^[12] Current Knots versions follow the split-off chain, including as an app in a node system.^[9] Only download software from the official project website.

3. Let it sync

   The node downloads and checks every block, from the genesis block in 2009 up to the current block 970,043. Leave it running until it has caught up.

4. Connect your wallet

   Many wallets can connect to your own node. Public servers then no longer learn which addresses and which balance belong to your IP address.^[13]

5. Look after it

   Install updates, set strong passwords, don’t open unnecessary ports on your router and, if possible, run it over Tor.

Dive deeperHow to check that your download is genuine

Tampered software could show you false data. According to bitcoin.org, this is how you check Bitcoin Core:^[10]

1. Download the checksum list: Every release comes with a list of the SHA-256 hashes of all files, digitally signed by the project’s developers.
2. Check the signatures: Using PGP, you check whether the list was signed with the expected keys.
3. Compare the hash: Calculate the SHA-256 hash of your file. Install only if it matches the value in the list.

With a ready-made node system, you trust its update process instead. That’s fine, as long as it’s a conscious decision.

Checklist: ready for your own node?

What’s next?