What Is a Node in Crypto? Blockchain Nodes Explained (2026)

What is a node?

The word “node” turns up in computer networking, maths, biology and even astrology. It generally means a connection point in a network. This guide is about nodes in crypto and blockchain, where the meaning is specific.

A blockchain node is a computer running a blockchain’s software and connected to other computers running the same software. Ethereum.org’s nodes and clients documentation defines an Ethereum node as any instance of Ethereum client software that is connected to other computers also running Ethereum software, forming a network. Bitcoin.org’s full node guide describes a Bitcoin full node as a program that fully validates transactions and blocks.

The network has no central server. Our what is blockchain guide explains the ledger itself; nodes are the computers that keep copies of that ledger, share new data and agree on which version is valid.

What a blockchain node actually does

Different blockchains work differently, but a typical full node does four jobs:

1. Finds peers. A new node has to discover other nodes. Bitcoin’s peer-to-peer network guide explains that, when first started, Bitcoin Core queries DNS seeds hard-coded into the software to get the addresses of full nodes that may accept connections. Ethereum’s networking layer has its own discovery process.
2. Receives and relays data. When you send a transaction, your wallet hands it to a node, which passes it on. Bitcoin.org says almost all full nodes accept transactions and blocks from other full nodes, validate them, and relay them to further full nodes.
3. Checks the rules. A full node checks each transaction and block against the protocol rules: signatures are valid, coins are not spent twice, blocks are properly formed. Ethereum.org describes full nodes doing a block-by-block validation, including the block body and state data. Anything invalid is rejected.
4. Keeps a copy and answers questions. The node stores the blockchain, or at least recent data, and can answer queries such as a balance or a transaction’s status for its owner or for the apps connected to it.

This is the meaning of the phrase “don’t trust, verify”, which ethereum.org uses in its node docs: a full node does not need to trust anyone else’s version of the ledger, because it checks the data itself.

Full, light and archive nodes

Not every node stores or checks the same amount of data. The main types are:

Full nodes. Ethereum.org notes there are different classes of full node: some verify every block from the genesis block, others start from a recent block they trust and verify from there. On Bitcoin, Bitcoin.org explains that a node can run in pruned mode, cutting disk use from over 750 GB to around 7 GB, while still validating everything. The trade-off is that a pruned node cannot serve old blocks to others.

Light nodes. The idea goes back to section 8 of the Bitcoin whitepaper, “Simplified Payment Verification”, which says it is possible to verify payments without running a full network node by keeping only the block headers. Ethereum.org’s light clients page explains that Ethereum light clients rely on a sync committee of 512 validators, randomly selected every 1.1 days, that signs recent block headers. Light nodes use far less hardware, but rely more on full nodes for data.

Archive nodes. Ethereum.org’s archive node page says archive nodes keep all historical states, which is needed to ask questions like an account’s balance at an old block. It notes most clients need more than 12 TB for an archive, while some implementations can store it in under 3 TB. That is why archive nodes are mostly run by explorers, wallet companies and analytics services, not individuals.

Nodes vs miners vs validators

People often use “node”, “miner” and “validator” as if they mean the same thing. They do not. Our proof of work vs proof of stake guide covers the two consensus systems in depth; here is how nodes fit in.

Bitcoin miners propose blocks; nodes check them. In proof of work, miners compete to produce the next block, as explained in our Bitcoin mining guide. A miner needs a node to know the current chain, but most nodes do not mine. Crucially, every full node checks each new block itself. A block that breaks the rules is rejected by honest full nodes no matter how much computing power went into it. The Bitcoin whitepaper says the system is secure as long as honest nodes collectively control more CPU power than any cooperating group of attackers.

Ethereum validators are nodes with extra duties. Ethereum.org explains that every Ethereum node runs two clients: an execution client and a consensus client. Its proof-of-stake page says a validator must deposit 32 ETH into the deposit contract and run a third piece of software, a validator client. Time is divided into 12-second slots; in each slot one validator is randomly chosen to propose a block and a committee of validators votes on it. Other nodes re-execute the transactions to check the proposed changes. Validators who act dishonestly, for example by proposing two blocks for one slot, can have some or all of their staked ETH destroyed.

So a validator is always running a node, but a node does not have to be a validator. Ethereum.org notes that if you run a full node, the whole Ethereum network benefits from it, even if you do not run a validator. This guide covers the mechanics only; it does not cover staking returns or recommend staking.

Lightning nodes

The Lightning Network is a payment layer built on top of Bitcoin, explained in our what is the Lightning Network guide. It has its own nodes, which are different from Bitcoin full nodes.

A Lightning node opens payment channels with other Lightning nodes. Lightning Labs’ Lightning Network overview says a sender has to find a route from their node through routing nodes to the recipient. Channels are publicly known, but whether a given node is online and has enough liquidity is not, so wallets may try several routes. A Lightning node also relies on the Bitcoin blockchain underneath, either through its own Bitcoin node or by connecting to someone else’s.

Some Lightning wallets are custodial and use the provider’s nodes, while others run a node inside the app, so you may be using a Lightning node without managing one yourself.

RPC and node providers: using someone else’s node

Most people never run a node. Their wallet or app connects to one instead. Ethereum.org’s JSON-RPC documentation explains that any software that wants to read Ethereum data or send transactions must connect to an Ethereum node, and every Ethereum client implements a standard JSON-RPC interface for this. The address an app connects to is often called an RPC endpoint, and a node set up to answer these requests is often called an RPC node.

Running nodes that can handle heavy traffic is hard work, so a whole industry offers it as a service. Ethereum.org’s nodes as a service page says these providers run node infrastructure and typically give you an API key. It also lists the main drawback: using a node service centralises that part of your product, which is why projects that put decentralisation first may prefer to host their own nodes.

For an everyday user, the practical point is who you are trusting. When your wallet uses a provider’s node, you rely on that provider to show you accurate data and to pass your transactions on, and it can see the requests your wallet makes. Ethereum.org says running your own node lets you use Ethereum in a private, self-sufficient and trustless way. Gas and fee estimates also come from nodes; our Ethereum gas guide and Bitcoin transaction fees guide explain how fees are set.

Why node count and diversity matter

More independent nodes make a network harder to control. Ethereum.org says more nodes result in a more diverse and robust network, the goal of decentralisation, which enables a censorship-resistant and reliable system. Bitcoin.org adds that full nodes serve lightweight clients, and if not enough nodes do this, clients will have to use centralised services instead.

Software diversity matters too. Ethereum.org’s client diversity page explains why many independent clients are healthier than one dominant one. A bug in a consensus client used by more than a third of nodes could stop the chain from finalising, and a critical bug in a client with a two-thirds majority could cause the chain to split and finalise incorrectly.

Node counts are estimates. Websites that count nodes crawl the network by connecting to the nodes they can reach. Ethereum.org notes that, because of the nature of decentralised networks, these crawlers provide a limited view and may report different results. Bitcoin.org notes that home connections are usually filtered by a router, so many home nodes connect out but do not accept inbound connections. They still verify the chain for their owners, but crawlers generally cannot reach them to count them. Treat any single headline figure with caution.

Running a node from Australia

Running a node from home is possible on ordinary hardware for some networks and demanding for others. These are the published requirements at the time of writing; check the official pages before buying anything, because they change as blockchains grow.

Sources: Bitcoin.org’s Bitcoin Core requirements and ethereum.org’s spin up your own node guide. Ethereum.org also points to higher recommended specifications (EIP-7870) of a 4 TB NVMe SSD, 32 GB RAM and 50 Mbit/s down and 15 Mbit/s up for a full node, with more for validators.

Upload speed and data. Upload is easy to overlook. Bitcoin.org says it is common for full nodes on high-speed connections to upload 200 GB or more a month, and warns that some plans charge extra for excess upload and some providers may terminate a connection because of overuse. nbn speed tiers list separate download and upload speeds, and the speeds available depend on your connection technology, so check your plan’s upload speed and any data or fair-use terms with your provider. Bitcoin Core can limit how much it uploads if you need to.

Leave it running. Bitcoin.org suggests at least 6 hours a day, ideally around the clock, and warns that sleep and power-saving modes can halt network traffic. The first sync, called the initial block download, can take a long time and use a lot of bandwidth and CPU.

Electricity and heat. A node that runs 24/7 adds to your power bill. The amount depends on your hardware and tariff, so check the device’s power draw and your plan; the government’s Energy Made Easy site compares electricity offers in many states. A small, efficient computer usually costs less to run than an old desktop.

Inbound connections. To help other nodes, Bitcoin.org says you need to allow inbound connections on Bitcoin’s port 8333, which can mean port forwarding on your router. You can run a node without this for your own verification.

Plug-and-play options. Ethereum.org mentions preconfigured node boxes and single-board computers as easier routes. These are a convenience, not a requirement, and this guide does not recommend any product.

Node security basics

A node is a computer permanently connected to the internet, sometimes with a wallet attached. Bitcoin.org warns that people who want to disrupt the network may attack Bitcoin Core users in ways that can affect other things you do with your computer. The basics:

• Get software from the official source and verify it. The Bitcoin Core download page publishes SHA256 hashes and signatures for each release so you can verify the download before installing. Fake “node” apps are an easy way to deliver malware.
• Keep the RPC interface private. Bitcoin Core’s JSON-RPC interface documentation says not to enable RPC connections over the public internet, because the interface sends login credentials without encryption and has not been hardened for arbitrary internet traffic.
• Secure your router. The Australian Signals Directorate’s secure your Wi-Fi and router guide recommends changing the router’s default admin username and password and keeping its firmware updated. Only open the ports you need.
• Update the operating system. Ethereum.org’s guide says to keep your OS up to date to avoid issues and security vulnerabilities.
• Separate the node from your savings. If the node runs a wallet, protect it like any hot wallet. Bitcoin.org’s requirements page says encrypting the wallet may not be enough if the computer becomes infected with malware and describes offline (cold) storage for larger amounts.
• Never share your seed phrase. No genuine node software or website needs your seed phrase to “sync”, “validate” or “connect” your wallet. Moneysmart’s crypto scams page covers common tricks, and our crypto security guide and crypto scams guide go further.

A checklist before you run a node

1. Which blockchain, and which type of node (full, pruned, light or archive) do I actually need?
2. Does my computer meet the current requirements on the official project site, with room to grow?
3. Does my nbn plan have the upload speed and data allowance for months of continuous running?
4. Have I estimated the electricity cost of running the device 24/7?
5. Did I download the software from the official site and verify the checksum and signatures?
6. Is my router’s admin password changed, its firmware current, and the RPC port closed to the internet?
7. If a wallet runs on this machine, are my backups offline and is my seed phrase kept out of every website and message?

Running a node is optional. You can use Bitcoin or Ethereum without one, as explained in our crypto wallet guide, our what is Bitcoin guide and our what is Ethereum guide. It is a way to verify for yourself and to support the network, not a requirement.

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