Glossary · Blockchain basics

Public blockchain

Published 23 May 2025 · Updated 9 Nov 2026 · 15 min read

A public blockchain is a shared ledger anyone can read and send transactions to, maintained by independent nodes following the same open rules. On permissionless networks, block producers need stake or mining hardware, not an operator's approval. Public access does not guarantee privacy or remove legal obligations, and some public networks restrict who validates.

  • Open does not mean anonymous, because public addresses can be linked to people.
  • Providers may refuse service and other routes remain, but an issuer's freeze holds on every route.
  • Public blockchains face real rules in 2026, from the GDPR to sanctions law.
What makes a blockchain publicWhat open participation actually allowsWho can stop or delay transactionsWhat a public payment revealsHow anyone buys block spacePublic, consortium and private chains comparedWhich rules apply to public blockchainsMilestones in public blockchain historyWhere public blockchains have limitsBuilding products on public networksPublic blockchain FAQ

What makes a blockchain public

A public blockchain ledger lets anyone read records and submit transactions. On a permissionless network, no administrator decides who may join, unlike a database run by one company. It is one form of distributed ledger, not a synonym for every shared database. The definitions below separate access from authority. NIST IR 8202, published in October 2018, ties permissionless participation to reading, writing and publishing blocks without authorization.

SourceDateDefinition, in its own wordsWhat it adds
NIST IR 8202, Blockchain Technology OverviewDateOctober 2018Definition, in its own words“In a permissionless blockchain network anyone can read and write to the blockchain without authorization.”What it addsThe standard test: no one's permission to read or write
EDPB Guidelines 02/2025, paragraph 22DateFinal version 7 July 2026Definition, in its own words“Permissionless blockchains provide participants with equal rights and capacities: anyone can read, write, or create blocks.”What it addsThe EU data regulators' wording, which adds creating blocks
ethereum.org, NetworksDateUpdated 23 September 2026Definition, in its own words“Anyone can read or create transactions on a public blockchain and validate the transactions being executed.”What it addsA network's own description, with validation open to all
Bitcoin white paperDateAnnounced 31 October 2008Definition, in its own words“nodes can leave and rejoin the network at will”What it addsOpen joining and leaving, with no membership list
World Bank, FinTech Note No. 1Date2017Definition, in its own words“Distributed ledgers are categorized as public or private depending on whether the ledgers can be accessed by anyone”What it addsSeparates who may read from who may write
BIS Annual Economic Report 2018, chapter VDate24 June 2018Definition, in its own words“while anybody can participate, nobody has a special key to change the ledger.”What it addsNo administrator key, changes only by consensus

Two axes matter: who may read, and who may write and validate. Public or private describes access. Permissionless participation or a permissioned ledger describes authorization. The Bitcoin network and Ethereum network are public permissionless examples. A public permissioned network separates those choices. Hedera's consensus nodes are permissioned and operated by its council, while mirror nodes are permissionless. Public access does not guarantee decentralized block production or permission for every node to become a validator.

Bitcoin is pseudonymous, not anonymous. Its documentation says it cannot offer cash's level of privacy. A blockchain explorer can expose an address's balance and payment history without displaying a person's name. The BIS chapter published in June 2018 described cryptocurrencies as anonymous, but Bitcoin's documentation contradicts that wording. Transparent records and absent names are different properties. Anyone can see the balance and all transactions of any Bitcoin address.

What open participation actually allows

Access involves different jobs, not one universal permission. The table separates reading, sending transactions, producing blocks, operating a node, building applications and changing rules. Bitcoin and Ethereum allow open participation, but each job carries different costs. Permissionless describes authorization, not free computing resources or automatic influence over upgrades.

Anyone canOn BitcoinOn EthereumWhat it takes
Read the ledgerOn BitcoinAll transactions are public, traceable and permanently stored (bitcoin.org)On EthereumAnyone can read transactions and verify them with their own client (ethereum.org)What it takesA node of your own, or a provider's node or an explorer
Send a transactionOn BitcoinPay a fee rate that miners accept. Bitcoin Core v32.1 relays from 0.1 sat/vB by defaultOn EthereumPay at least the base fee, usually plus a tip. Up to 16,777,216 gas per transaction since December 2025What it takesCoins for the fee and a wallet
Produce blocksOn BitcoinMine with specialized hardware. A miner's share of blocks follows its hash powerOn EthereumStake at least 32 ETH per validator, and up to 2,048 ETHWhat it takesHardware and power, or stake
Run a full nodeOn BitcoinAbout 7 GB of disk when pruned, 2 GB of RAM, 400 kbit/s upload (bitcoin.org)On Ethereum16 GB of RAM, 32 GB recommended, a 4 TB NVMe SSD and 25+ Mbit/s (ethereum.org)What it takesA machine that stays online, at home or in the cloud
Build on itOn BitcoinBitcoin Core is open source under the MIT licenseOn EthereumNo rules on who can build an application (ethereum.org)What it takesCode, and no approval
Propose rule changesOn BitcoinNobody owns the network. Changes need users to choose new software (bitcoin.org)On EthereumGovernance happens off-chain, and node operators can decline an upgrade (ethereum.org)What it takesPersuade users and node operators, or fork

Reading and sending transactions need no admission approval. An Ethereum validator requires at least 32 ETH. Bitcoin block production needs specialized hardware, and share follows hash power. A full node verifies rules but needs an online machine. ethereum.org warns that cloud concentration can create a single point of failure. Users and node operators choose software, so rule changes depend on adoption. RPC provider access offers another way to read data.

Who can stop or delay transactions

A public blockchain has several points where a transaction can be refused. The interface, connection service and block producer have different powers. Censorship resistance varies by layer, since refusal at one layer does not necessarily control the network. Select Bitcoin or Ethereum to distinguish a rejected request, delayed inclusion, a token freeze and legal obligations.

Figure 1 · Page team map of the transaction pathFollow a transaction's pathChoose Bitcoin or Ethereum, then select each layer to see its powers, alternative paths, dated cases, sources and three network readings.
Network
Wallet or websiteCan refuse its own routeA wallet or front end can decline to build or show a transaction in its own interface.
Protocol alternative, where the law allows
Another wallet, another interface, or a node of your own can send the same valid transaction
Dated case
In August 2022 the website and code repository of Tornado Cash, an Ethereum application, went offline (FTI Consulting, 19 August 2022)
Sources
ethereum.org nodes page, FTI Consulting
RPC providerCan refuse its own routeA provider's node can decline requests. It also sees the IP address and the addresses a user asks about.
Protocol alternative, where the law allows
Another RPC endpoint, or a node of your own
Dated case
On 9 August 2022 two large providers blocked API access for Tornado Cash users (The Block, corrected to API rather than RPC access)
Sources
ethereum.org privacy roadmap, The Block
Block builder and relayCan refuse its own routeA builder can leave a transaction out of the blocks it builds, and a relay can refuse to pass those blocks on.
Protocol alternative, where the law allows
Other builders, or a proposer that builds its own block. A censoring builder must outbid all non-censoring builders (ethereum.org)
Dated case
16.7% of MEV-Boost deliveries went through relays classed as censoring on 7 November 2026, down from 94.8% on 26 October 2022
Sources
ethereum.org MEV page, mevwatch.info
Block proposerCan leave out one blockThe validator chosen for a slot decides which transactions go into that one block.
Protocol alternative, where the law allows
The next slot has a different proposer. FOCIL inclusion lists would force inclusion, once live on mainnet
Dated case
A 2023 study found censored transactions delayed by an average of 85%
Sources
ethereum.org Hegotá page, arXiv 2305.18545
Majority of stakeCan censor while it holds a majorityValidators with more than half of the stake could censor transactions and reorder recent blocks for as long as they hold it.
Protocol alternative, where the law allows
The social layer: the community can adopt an honest fork and leave the attacker's stake behind
Dated case
ethereum.org lists 51% as enough for censorship and control over the chain's future
Sources
ethereum.org proof-of-stake attack and defense
Stablecoin issuerCan freeze its own tokenAn issuer can freeze its own token at an address. It cannot touch ETH or tokens it does not issue.
Protocol alternative, where the law allows
None on-chain for that token. The issuer's terms and the courts apply
Dated case
On 8 August 2022 Circle said it blocked the addresses associated with OFAC's Tornado Cash designation
Sources
Circle stablecoin token design, The Block
Regulators and courtsBinds people and firmsSanctions bind people and firms within reach, such as front ends, providers, issuers, pools and validators. They do not edit the consensus rules.
Protocol alternative, where the law allows
Legal process only. OFAC says obligations apply equally to virtual currency, whatever software a person uses
Dated case
OFAC listed digital currency addresses for the first time on 28 November 2018 and designated Tornado Cash on 8 August 2022. Van Loon (26 November 2024) and the delisting (21 March 2025) followed
Sources
US Treasury and OFAC, Fifth Circuit
Relay deliveries that filter sanctioned addresses16.7%Share of MEV-Boost deliveries on 7 November 2026 (mevwatch.info)
Peak of that share94.8%26 October 2022 (mevwatch.info)
Inclusion lists (FOCIL)PlannedEIP-7805, scheduled for Hegotá with no mainnet date
Wallet or websiteCan refuse its own routeA wallet or front end can decline to build or show a transaction in its own interface.
Protocol alternative, where the law allows
Another wallet, another interface, or a node of your own can send the same valid transaction
Dated case
In August 2022 the website and code repository of Tornado Cash, an Ethereum application, went offline (FTI Consulting, 19 August 2022)
Sources
ethereum.org nodes page, FTI Consulting
Node or server you queryCan refuse its own routeA server that a light wallet relies on can refuse to pass a transaction on, and it can log IP addresses.
Protocol alternative, where the law allows
Another server, or a full node of your own
Dated case
bitcoin.org warns that it is possible to listen for transaction relays and log IP addresses
Sources
bitcoin.org, Protect your privacy
Relay policy of nodesCan refuse its own routeEach node applies its own relay policy, such as a minimum fee rate, before passing a transaction to its peers.
Protocol alternative, where the law allows
Pay a fee rate that nodes relay, or reach a miner through other peers
Dated case
Bitcoin Core lowered its default relay floor to 0.1 sat/vB in 2025
Sources
Bitcoin Core release notes 29.1 and 30.0
Mining poolCan leave out one blockA pool decides which transactions go into the blocks it mines. Blocks from other pools can still include them.
Protocol alternative, where the law allows
A later block from another miner
Dated case
One pool mined a sanctions-compliant block in May 2021 (block 682,170, 178 transactions). Another was found filtering in 2023 and said it would stop
Sources
The Block, b10c.me, CoinDesk
Majority of hash powerCan censor while it holds a majorityMiners with half of the computing power could block or reverse recent transactions for as long as they hold it.
Protocol alternative, where the law allows
Users and nodes can choose software that rejects the attack, at the cost of a fork
Dated case
bitcoin.org describes this limit in its FAQ
Sources
bitcoin.org FAQ
Regulators and courtsBinds people and firmsSanctions bind people and firms within reach, such as front ends, providers, issuers, pools and validators. They do not edit the consensus rules.
Protocol alternative, where the law allows
Legal process only. OFAC says obligations apply equally to virtual currency, whatever software a person uses
Dated case
OFAC listed digital currency addresses for the first time on 28 November 2018 and designated Tornado Cash on 8 August 2022. Van Loon (26 November 2024) and the delisting (21 March 2025) followed
Sources
US Treasury and OFAC, Fifth Circuit
Default relay floor0.1 sat/vBBitcoin Core v32.1, tagged 26 October 2026
Fee estimates0.1 to 2.5 sat/vBmempool.space, 8 November 2026
Block target10 minutesEach block goes to a miner with odds that follow hash power

A wallet, RPC provider or relay can refuse service, while other software or providers can carry the same valid transaction.

One block producer can omit a transaction from its block, while a later producer can include it.

A majority of stake or hash power could censor while it holds control, while the social layer can support a fork.

A stablecoin issuer can freeze its own token at an address, but cannot freeze BTC or ETH.

Regulators and courts bind people and firms within their reach, rather than rewriting the network's consensus rules.

This page team map traces the transaction path with dated cases and readings. It is not legal advice.

Wallets, RPC providers, builders and relays can refuse service, making network decentralization more than a protocol property. Another node can submit valid transactions. In August 2022, the Tornado Cash front end went offline. Circle froze designated USDC addresses on 8 August 2022. The next day, providers blocked API access, not RPC access. The 7 November 2026 reading shows 16.7% of MEV-Boost deliveries through relays classified as censoring. The peak was 94.8% on 26 October 2022. This is delivery share, not an exact block count.

No individual Ethereum producer can undo finality. Majority stake or hash power can censor or reorder recent blocks. Issuers control only their tokens. In Van Loon, the Fifth Circuit ruled on 26 November 2024 that Tornado Cash's immutable contracts were not property of a foreign national or entity. Treasury's delisting followed on 21 March 2025. In November 2026, draft FOCIL, EIP-7805, is scheduled for Hegotá without a mainnet date. Its proposed validator inclusion lists would require blocks to include listed mempool transactions.

What a public payment reveals

A transparent ledger exposes more than a transaction amount. Bitcoin and Ethereum records differ, and privacy-focused designs expose different fields. Pseudonymous participation does not make those fields confidential. Compare six payment types, including what becomes visible in a public mempool before a swap is included in a block.

Figure 2 · Protocol documentation, with made-up example valuesInspect six payment typesSelect a payment to inspect eight fields marked public, linkable, hidden, parties only or metadata only.
Payment
A Bitcoin paymentFully publicExample: 0.015 BTC paid from two inputs, with change sent back to the payer
SenderTwo input addresses bc1q…7x2k and bc1q…p3rePublic
Receiverbc1q…m9fdPublic
Amount0.015 BTCPublic
Change0.0031 BTC to a new address of the payerLinkable
FeeInputs minus outputsPublic
Time and blockThe block time set by the minerPublic
Same ownerBoth inputs reveal one ownerLinkable
Who and whyKnown to payer and payeeParties only
An ETH transferFully publicExample: 0.5 ETH sent from one account to another
From0x3f2a…9c1ePublic
To0x8b07…d44aPublic
Value0.5 ETHPublic
NonceThe sender's 412th transactionLinkable
FeeGas used times the price paidPublic
Input dataEmpty for a plain transferPublic
Time and blockBlock number and timestampPublic
Who and whyKnown to sender and recipientParties only
An ERC-20 token transferFully publicExample: 250 units of a stablecoin, recorded by its Transfer event
From0x3f2a…9c1ePublic
To0x51c9…a0f3Public
Amount250 tokensPublic
Token contractThe contract that emitted the logPublic
Outer transactionSender, nonce and fee in ETHPublic
Time and blockBlock number and timestampPublic
Freeze statusSet by the issuer, if it has that rolePublic
Who and whyKnown to sender and recipientParties only
A swap on a decentralized exchangePublic before and afterExample: one token swapped for another in a pool
Trader0x3f2a…9c1ePublic
PoolThe pool contract and its token pairPublic
AmountsBoth amounts, in and outPublic
Price afterThe pool price after the swapPublic
Before it landsVisible if sent to the public mempoolPublic
FeeGas plus the pool's swap feePublic
RecipientCan differ from the traderPublic
Who and whyKnown to the traderParties only
A Zcash shielded transactionMostly hiddenExample: a payment from one shielded address to another
SenderNot revealed, even to the receiverHidden
ReceiverEncryptedHidden
AmountEncryptedHidden
MemoEncryptedHidden
FeeVisible to everyonePublic
That it happenedBlock and timePublic
Spends and outputsShown on Sapling, hidden on OrchardDepends on the pool
Entering or leaving the poolValue revealedPublic
A transfer on the Canton NetworkPrivacy-preservingExample: a transfer between two parties, described in Canton's own documentation
SenderNamed in informee messages to the mediatorMetadata only
ReceiverNamed in informee messages to the mediatorMetadata only
AmountSeen by the parties' nodesParties only
Contract termsEach party sees only its viewParties only
SynchronizerEncrypted messages and confirmation resultsMetadata only
SequencersRecipient lists and message sizesMetadata only
Other nodesNo contracts: nodes store only their parties' contractsNot stored
IdentityParty hosting is known to every synchronizer nodeMetadata only
Public: anyone can read it. Linkable: public data that analysis can tie to a person. Hidden: not readable from the chain. Parties only: shown to no one else. Metadata only: operators see who and how much data, not the contents.

Bitcoin inputs, outputs, amounts and the fee are public and unencrypted, while common inputs reveal a shared owner.

Ethereum exposes from, to, value and fee, while the nonce links transactions originating from the same account.

The token contract's Transfer event records from, to and amount, and the log identifies which token contract emitted it.

A pending mempool swap is public before inclusion, and the recorded trade exposes both amounts and the price after execution.

Zcash shielded transfers shield addresses, amounts and memos, while the fee and value entering or leaving a shielded pool remain visible.

Only informees can decrypt Canton transfer views. The synchronizer handles encrypted messages, while sequencers see recipient lists and message sizes.

Example values are made up. The visibility assigned to each field follows the relevant protocol documentation.

Bitcoin exposes a change output alongside payment outputs in most transactions. An ETH transfer shows from, to, value, nonce and input data. ERC-20 token transfers add a Transfer log, while plain ETH transfers emit no log. Uniswap v3 swaps also record the resulting price. A blockchain address can become identifiable through common inputs, change heuristics or exchange identity checks. Nodes and RPC providers can log IP addresses. The EDPB's guidelines adopted on 7 July 2026 treat public keys as personal data when identification uses reasonably likely means.

Zcash shielded transfers hide amounts, addresses and memos but expose fees. Sapling reveals counts of spends and outputs, while Orchard also hides that split. Canton describes itself as a public layer 1 blockchain that splits a transaction into encrypted views for its informees. Its participant nodes store only contracts involving their hosted parties. The synchronizer never accesses transaction data, so public participation does not mean every node receives the same readable payment record.

How anyone buys block space

Admission to a public blockchain does not reserve capacity. Ethereum measures transaction work in units of gas, while Bitcoin miners select payments by their offered rate. This is an open market, not an account approval process. Adjust demand in the model to see pricing change, then compare it with a dated replay.

Figure 3 · Page team model of EIP-1559 and a replay of 25 blocksWatch the base fee moveSimulate 25 blocks from empty to full, or replay Ethereum blocks from 8 November 2026 to compare modeled and observed changes.
Mode
70% full
Base fee over the next 25 blocks at this demandFee risingBlock 1Block 25
Ethereum blocks 26,373,559 to 26,373,583, 8 November 2026Real blocks26,373,55926,373,583
Block fuller than the target, next base fee risesBlock at or below the target, next base fee holds or falls
Base fee in block 250.3476 gweiStarting from 0.1078 gwei, the last block read
Change+223%At most 12.5% up or down per block
Base fee of a plain transfer0.0000073 ETH21,000 gas, burned, before any tip
Blocks fuller than the target11 of 25Target: half of the 60 million gas limit
Base fee range0.1078 to 0.1511 gweiBlocks from 23:51 to 23:56 UTC, read from a public RPC endpoint
Base fees the rule predicts24 of 24Recomputed from each parent block, exact to the wei

Above-target blocks raise the base fee by up to 12.5% each. Six full blocks roughly double it in the model.

Blocks that use exactly the target gas leave the base fee where it is, block after block.

Blocks below the target lower the base fee by up to 12.5% each, and five empty blocks roughly halve it.

The 8 November 2026 replay reproduces all 24 base fee changes exactly, to the wei, across 0.1078 to 0.1511 gwei.

This page team EIP-1559 model includes a replay of 25 Ethereum blocks read on 8 November 2026.

Ethereum's transaction fee combines a burned base fee with any priority fee paid to the proposer. EIP-1559 limits each adjustment to 12.5%. Client releases for Fusaka made 60 million gas the default block limit, with a target of half that. The page team's 8 November 2026 replay matches all 24 changes across 25 blocks exactly. Bitcoin miners choose by fee rate. Estimates on 8 November 2026 span about 0.1 to 2.5 sat/vB. Bitcoin Core 31.0 introduced cluster mempool ordering in April 2026.

Public, consortium and private chains compared

Network categories describe access, authority and visibility, not a security ranking. A public blockchain can be transparent and permissionless, or readable by everyone with approved validators. A consortium shares control among selected participants. A private blockchain reserves access. Pseudonymous accounts and identified parties also create different expectations about who sees records.

TopicPublicPublic permissionedConsortiumPrivate
Who can readPublicAnyonePublic permissionedUsually anyone. Hedera's mirror nodes are open to allConsortiumMembers, or the public if members choosePrivateWhoever the operator allows
Who can write and validatePublicAnyone can send. Anyone with stake or hash power can produce blocksPublic permissionedAnyone can send on Hedera. Approved operators validateConsortiumA pre-defined set of trusted nodesPrivateThe operator
Who you trustPublicThe protocol rules, checked by your own node or a provider'sPublic permissionedA council or a set of named operatorsConsortiumThe member firms and their agreementPrivateOne organization
Who sees the dataPublicEveryone, under pseudonymous addressesPublic permissionedEveryone, in the examples readConsortiumMembersPrivateThe operator and the users it allows
How rules changePublicOff-chain debate, client upgrades and forksPublic permissionedCouncil or member decisionsConsortiumMember agreementsPrivateThe operator decides
ExamplesPublicBitcoin (2009), Ethereum (2015)Public permissionedHedera, LACChain, Alastria Red BConsortiumPartior (founded 2021)PrivateKinexys by J.P. Morgan, HSBC Tokenised Deposit Service

A public blockchain trades operator control and privacy for open participation and shared rules. A private blockchain reverses those priorities, but isolation does not establish security. A consortium relies on a predefined trusted node set. Canton does not fit one column. It calls itself a public layer 1 blockchain. Its Global Synchronizer is operated by Super Validators. A new validator needs sponsorship from a Super Validator, and each party sees only its own data.

Which rules apply to public blockchains

Open participation does not exempt people or businesses from regulation. The table covers the GDPR, MiCA, the EU travel rule, FATF standards, US sanctions and the GENIUS Act. For public blockchains, legal duties depend on roles and jurisdiction, not simply whether the network describes itself as decentralized.

RuleWho it applies toWhat it means for a public chain
GDPR, with EDPB Guidelines 02/2025 (final 7 July 2026)Who it applies toControllers of personal data, which can include nodes that decide purposes and meansWhat it means for a public chainPublic keys can be personal data. Use a public chain only if public access is needed, and design erasure in from the start
MiCA, Regulation (EU) 2023/1114Who it applies toCrypto-asset service providers in the EU, licensed by 1 July 2026 at the latestWhat it means for a public chainFully decentralized services are out of scope. Providers disclose each asset's consensus energy use (Delegated Regulation 2025/422)
Transfer of Funds Regulation (EU) 2023/1113, from 30 December 2024Who it applies toCrypto-asset service providers in the EUWhat it means for a public chainNames and addresses travel with each crypto transfer, with no EUR 1,000 threshold
FATF Recommendation 16, updated 18 June 2025Who it applies toCountries and the providers they regulateWhat it means for a public chainThe travel rule for virtual assets, with the 2025 changes in effect by the end of 2030
US sanctions: IEEPA and OFAC guidance of 15 October 2021Who it applies toUS persons, including firms that run front ends, nodes or validatorsWhat it means for a public chainObligations apply equally to virtual currency. Courts review designations, as in Van Loon (26 November 2024)
GENIUS Act, enacted 18 July 2025, effective 18 January 2027Who it applies toIssuers of payment stablecoins in the USWhat it means for a public chainIssuers must be able to seize, freeze or burn their tokens on a lawful order

These rules bind providers, issuers and personal data controllers, not the protocol itself. The EDPB's final guidelines of 7 July 2026 ask whether public access is necessary. They reject technical impossibility as an excuse for GDPR noncompliance and require erasure rights to be addressed by design. The GENIUS Act takes effect on 18 January 2027. Payment stablecoin issuers must be technically able to comply with lawful orders, including freezes, and must follow them. This page is not legal advice.

Milestones in public blockchain history

From Bitcoin's first block in 2009, public blockchains developed through software choices, forks, sanctions and data protection law. Ethereum's launch in July 2015 brought another permissionless network. Later disputes split shared histories, while regulators addressed personal data and obligations on providers.

  1. January 2009

    Bitcoin begins recording blocks

    The Bitcoin genesis block was created on 3 January 2009 at 18:15:05 UTC. It followed the white paper announced on 31 October 2008, which described payments without a financial institution.

  2. July 2015

    Ethereum launches with Frontier

    Ethereum's Frontier release went live on 30 July 2015 at block 0 as another public permissionless network. Transactions became possible once the Frontier thawing fork lifted the 5,000 gas block limit on 7 September 2015.

  3. July 2016

    The DAO fork divides Ethereum

    The DAO fork occurred on 20 July 2016 at block 1,920,000. Some miners refused to fork, and the unforked chain continued as Ethereum Classic. Shared history did not prevent different communities adopting different rules.

  4. August 2017

    Bitcoin Cash separates from Bitcoin

    Bitcoin Cash split from Bitcoin on 1 August 2017 after block 478,558. The public blockchain divided when participants adopted different software rather than settling on one rule set.

  5. September 2018

    CNIL addresses blockchain data protection

    The CNIL published blockchain and GDPR guidance on 20 September 2018, followed by an English version on 29 October 2018. It stressed the importance of keeping personal data off a blockchain in cleartext.

  6. August 2022

    Sanctions reach Tornado Cash services

    OFAC designated Tornado Cash on 8 August 2022. Circle blocked designated USDC addresses that day, and API providers blocked access the next day. These actions occurred at service and token layers rather than rewriting Ethereum's rules.

  7. November 2024

    Van Loon limits sanctions authority

    The Fifth Circuit ruled in Van Loon on 26 November 2024 that Tornado Cash's immutable contracts were not property of a foreign national or entity. Treasury removed the sanctions on 21 March 2025.

  8. July 2026

    EDPB adopts final blockchain guidelines

    The EDPB adopted version 2.0 of Guidelines 02/2025 on 7 July 2026. Its framework separated public access from permission to participate and required data protection obligations to be considered in the design.

Where public blockchains have limits

Openness does not settle questions about retention, capacity, recovery or resource use. A public blockchain can preserve records while leaving users exposed to mistakes and intermediaries. Records written openly to a public chain stay there and remain visible to everyone.

Public data persists

The EDPB's July 2026 guidelines describe no practical deletion option for most on-chain data. Bitcoin documentation warns that records difficult to trace today may become easy to trace later.

Demand changes fees

Bitcoin's 20 April 2024 halving block had a median fee of 200 sat/vB. Estimates on 8 November 2026 range from about 0.1 to 2.5 sat/vB, illustrating changing demand.

Lost keys prevent access

Lost Bitcoin keys can leave coins dormant forever. Chainalysis counted about 3.7 million BTC unmoved for at least five years in June 2020, but inactivity does not prove loss.

Communities can split

Ethereum's DAO fork produced Ethereum Classic in July 2016. Bitcoin Cash split in August 2017. Public blockchain governance depends on software adoption, not a universal administrator.

Intermediaries can censor

Providers restricted Tornado Cash API access in August 2022. On 7 November 2026, relays classified as censoring handled 16.7% of MEV-Boost deliveries, a delivery-share measure rather than an exact block count.

Energy requirements differ

Cambridge estimated Bitcoin's annual electricity use at 138 TWh on 28 April 2025. Its 10 July 2026 estimate for Ethereum after the Merge was about 7.87 GWh annually.

Building products on public networks

We build products for public networks, from smart contracts and tokens to protocol design. Our public blockchain development work covers open, transparent and permissionless networks. We also address the choice between public, consortium and private blockchain architectures. PixelPlex is a software engineering company founded in 2007, with blockchain work dating to 2013.

PixelPlex case icon

The KickICO crowdfunding case documents an Ethereum platform for reward and donation-based crowdfunding, launched in 2017 with its own KickCoin token. We built the ICO and KICK token contracts and an ICO contract generator. PixelPlex has built blockchain software since 2013.

  1. Protocols and applications

    We provide protocol design and dApp engineering for public blockchain products. This work includes smart contract development, blockchain integration and user adoption strategy.

  2. Tokens and contracts

    For CoinDepo's token platform in 2025, we created an Ethereum ERC-20 utility token and smart contracts managing tokenomics for payments, vesting and rewards.

  3. Ecosystem developer tooling

    For the TON ecosystem project in 2024, we built a proposal smart contract and created guides and instructions for developers working within that public network.

  4. Privacy-preserving participation

    PixelPlex is a Canton validator operator and runs its own production infrastructure that the ecosystem depends on daily. Our Canton development service includes deploying, configuring and managing participant nodes.

  5. Network type selection

    Our public versus private comparison explains network choices. We also offer private, consortium and hybrid development services, alongside work on permissionless public networks.

Discuss a product for a public blockchain

We can discuss your product's access, data and contract requirements, including where a public network fits and where it does not.

Discuss your project

Public blockchain FAQ

What is a public blockchain in simple terms?

It is a public ledger: a shared record that anyone can inspect and send transactions to, with independent nodes applying common rules. Bitcoin and Ethereum are permissionless examples, but block production still needs resources. Reading data, submitting a transaction and becoming a block producer are separate activities. Public access describes who can participate, not a guarantee of confidentiality or equal influence.

Is a public blockchain anonymous or pseudonymous?

Pseudonymous is the more accurate description for Bitcoin and Ethereum. A public address can be connected to a person through exchange records, reuse or payment patterns. Keeping a name out of a transaction differs from hiding its contents. A privacy assessment therefore needs to examine the transfer type and visible fields, not just the network's public label.

Who controls the rules of a public blockchain?

No single administrator can impose every decision across Bitcoin or Ethereum. Node operators choose software, while a validator or miner chooses what enters its own block. Ethereum governance happens offchain. A decentralized network still has influential participants and concentrated infrastructure. Control over an interface, block production and rule adoption should therefore be assessed separately.

Can a transaction on a public blockchain be censored?

Yes, an interface or block producer can refuse a transaction, but that refusal does not automatically bind other producers. Majority stake or hash power creates broader censorship risks. A token freeze is different because it changes whether that token can move under its contract. Legal obligations still apply when a transaction can technically reach another block.

How do public and private blockchains differ?

The main distinction is access: a private blockchain reserves participation, while public access allows anyone to read the ledger. Validation permissions form a separate axis. A consortium assigns consensus to a trusted group rather than opening it to everyone. Neither restricted access nor openness alone establishes whether a design satisfies its users' security or privacy requirements.

What are some examples of public blockchains?

Bitcoin and Ethereum are public permissionless networks. Hedera combines public access with permissioned consensus nodes. Zcash supports shielded transactions with different visibility rules. Canton calls itself a public layer 1 blockchain, with data visible only to relevant parties.

Does the GDPR apply to public blockchains?

Yes, personal data processing can fall under the GDPR even when records sit on a public blockchain. The EDPB's final Guidelines 02/2025, adopted on 7 July 2026, address this directly. A node may be a controller depending on who determines purposes and means. Neither pseudonymity nor deletion difficulties automatically remove compliance duties. This is not legal advice.

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