Layer 1 blockchain
Qtum ticker QTUM
Summary
Qtum keeps value in unspent outputs, following the Bitcoin Core code it forked, and runs Ethereum Virtual Machine contracts on top through an account abstraction layer. Blocks are made by staking, not mining: a coin output that has 2,000 confirmations may try to stake, and it wins when a hash of the previous stake modifier, the output's reference and a coarse timestamp falls below a target scaled by the output's value. Blocks target 32 seconds (128 seconds before April 2021) and carry the staker's signature. Since August 2020 holders can delegate staking to a super staker through a contract without giving up their keys; the same fork ended the whitepaper's shared-reward scheme. After the November 2025 halving the subsidy is 0.25 QTUM per block plus fees and gas. 123412192728
Design
- System
- Layer 1 blockchainPermissionless base chain in production since September 2017. Its node software is a fork of Bitcoin Core (rebased on Bitcoin Core 30.2 in July 2026) with proof of stake in place of mining and an Ethereum Virtual Machine layered on top of the unspent-output ledger. It has its own genesis block and settles to no other chain. The package label of base-layer blockchain is kept.
- Settlement family
- Bitcoin family
- Scarce resource
- Stake (proof of stake)
- State model
- Mixed
- Finality
- Probabilistic
- Who makes blocks
- Anyone holding mature QTUM in an online, unlocked Qtum Core wallet, with no minimum, validator registration or vote; or a super staker staking delegated coins for an agreed fee. In a qtum.info sample of 26 September 2026, 94 addresses produced that day's 2,705 blocks and the ten busiest produced about 87% of them, and in a spot check of every 25th block that day, 95 of 109 were made by super stakers on behalf of delegators. Addresses are not entities and one day is a small window.
- Fork choice
- Nodes follow the valid chain with the most accumulated proof, computed from each block's difficulty target with the chain-work calculation kept from Bitcoin Core, where a staked block's target is the stake difficulty. A running node also refuses any branch that forks more than 2,000 blocks (about 18 hours) below its own tip. That is a local rolling checkpoint, not a network-wide finality vote; hard-coded checkpoints ship with releases for nodes syncing from scratch.
Qualifications
- Finality · Partial. Settlement is probabilistic, but each running node refuses branches that fork more than 2,000 blocks below its tip. That caps how deep a reorganisation a live node will accept without being a shared finality vote. Qtum's exchange guide asks for 6, 10 or 20 confirmations depending on amount.
- State model · Partial. Value, including coins held by contracts, sits in unspent outputs, while contract code and storage live in an account-style state. Each block header commits to the contract state and to a separate record of which output each contract currently holds; it does not commit to the whole unspent-output set. The account abstraction layer translates between the two, so neither a pure output model nor a pure account model describes it.
- Settlement family · Partial. Grouped with Bitcoin-derived chains because transactions, scripts, signing and addresses follow Bitcoin Core. The Ethereum Virtual Machine runs inside those transactions, so Ethereum tooling works only through adapters such as Janus and a MetaMask Snap.
- Shared staking reward · Not applicable. The whitepaper describes rewards split across ten stakers with payment delayed 500 blocks. Current consensus code stops that split at block 679,999, the block before offline staking began in August 2020, so descriptions of it as live are out of date.
- On chain parameter governance · Applies. Contracts in the genesis block let block size, the per-block gas limit and the minimum gas price change without a hard fork. Qtum Core's defaults, which apply unless a vote sets other values, are 500,000 bytes per block since the 2021 block-time change (2 MB before), 40 million gas per block and 40 satoshi per unit of gas; qtum.org's technology page still says 2 MB. Who holds the voting rights today, and whether any vote has changed these values, was not verified; larger changes still ship as hard forks.
- Second virtual machine · Not applicable. The whitepaper describes an x86 virtual machine. Current Qtum Core transaction code defines only the Ethereum Virtual Machine as an executable contract engine, so the x86 design is not live.
- Throughput · Unknown. No primary-source throughput figure was classified. Figures on Ledger's Qtum page and on QiSwap's site are unsourced and were not recorded.
Tradeoffs
- Emphasizes
- Decentralization and Security Contested
- Gives up
- Base-layer capacity and fast settlement: blocks come about every 32 seconds under governance-set size and gas limits, confirmations give growing rather than final confidence, and payment channels exist only on testnet. Choosing stake over work also changes the security assumptions: safety rests on how stake is spread and on stakers keeping unlocked wallets online, and a node that was offline for a long time leans on checkpoints shipped with releases.The decentralization reading is contested. Staking has no minimum and runs on small hardware, but in a one-day qtum.info sample most blocks came from a few super-staker addresses staking delegated coins. Address counts are not entity counts and the sample was not repeated.
- Full node at home
- Practical at home 1112141718Qtum's exchange guide recommends at least 100 GB of disk for a mainnet node. Qtum's own staking guides run nodes on Raspberry Pi 2 to 4 images (September 2023 release) and on a one-CPU, 512 MB VPS with 2 GB of swap; those guides are dated. Staking needs the node online with the wallet unlocked, and a super staker must also build address and event indexes. Current chain size and bandwidth were not measured.
- Throughput claims
- No classified figure recorded
Scaling layers
- Qtum Lightning (Qtum Eclair client) · Payment channels, testnet 1015
Qtum's docs say its Lightning client, a port of Eclair, is supported only on testnet; the whitepaper dates a public beta to July 2019. The usual channel assumptions would apply: a party must watch for an old-state close, and channel balances limit what can move. No mainnet deployment or current maintenance was verified.
Capabilities
| Capability | How it is provided | Notes and sources |
|---|---|---|
| Account abstraction | Structured assessment pending | Not yet assessed for any chain. |
| Atomic swaps | Unknown | Not yet assessed under the current definitions; Qtum keeps the script inherited from Bitcoin Core, with absolute timelocks from genesis and relative timelocks from block 6,048, building blocks for hash-locked, time-locked swaps. The whitepaper records a QTUM to Bitcoin swap script in January 2019 and a QTUM to Beam swap in July 2019, but currently maintained swap tooling was not verified, so none is shown live. 110 |
| Authenticated data publication | Unknown | Not yet assessed under this row's current definition. |
| Light clients | Unknown | Not yet assessed under the current definitions; Qtum Electrum is described as a light wallet that uses simplified payment verification, but the docs do not explain how it checks a staked block's proof, which depends on the staked coin, so no light-verification method is specified. Its latest release (version 4.0.22, late 2023) predates the 2025 and 2026 hard forks, and current compatibility was not verified. 162324 |
| Native staking or delegation | Structured assessment pending | Not yet assessed for any chain. |
| On-chain governance | Structured assessment pending | Not yet assessed for any chain. |
| Parallel execution | Structured assessment pending | Not yet assessed for any chain. |
| Payment or state channels | Partial (layer not stated) Earlier definition | An Eclair-based Lightning client exists but Qtum's docs say it is supported only on testnet. See the scaling layers. 15 |
| Programmable spending | Native (protocol or core-team software) Earlier definition | Outputs carry script inherited from Bitcoin Core, and Ethereum Virtual Machine contracts are created and called through new script opcodes inside ordinary transactions. Another opcode lets a third party pay a call's gas. Inside contracts, values are in satoshi, and addresses and signing follow Bitcoin Core. 61013 |
| Protocol-verified messaging | Structured assessment pending | Not yet assessed for any chain. |
| Reversible transfers or recovery | Unknown | Not yet assessed under the current definitions; absolute and relative timelocks are building blocks with which wallets can build delayed or revocable spend paths, and contracts can hold funds under their own rules, but no cited source shows a sender-reclaim window or recovery path live. The protocol cannot reverse a confirmed payment, and cancelling a staking delegation is not a reversible transfer. 1 |
| Rollups | None found Earlier definition | No rollup settling to Qtum was found. The foundation describes the BLS12-381 precompile added in January 2026 as groundwork for zero-knowledge rollups, and the whitepaper lists a 2018 Plasma prototype, but no deployment of either was found. 1020 |
| Shielded transfers | Structured assessment pending | Not yet assessed for any chain. |
| Signed partial offers | Unknown | Not yet assessed under this row's current definition. |
Reading these values
- How this feature is provided
- Built into the protocol, core-team software or independent software says where a feature lives and who can change it. These are implementation layers, not quality: core-team software is not closer to the protocol than independent software.
- Structured assessment pending
- The shared review has not assessed this feature for any chain yet (Account abstraction, Native staking or delegation, On-chain governance, Parallel execution, Protocol-verified messaging and Shielded transfers). That does not mean it is absent, and a chain’s profile may already describe it.
- Unknown
- The review has not established this for this chain under the current definition; the note beside it says why. Unknown is not absent and not a low score. A feature reads “Not present” only when a source shows it is absent.
- Earlier definition
- Payment or state channels, Programmable spending and Rollups keep the earlier definition until the next fact-check. There, “Native” does not separate the protocol from core-team software, “Ecosystem software” does not say who publishes it, and “Partial” does not say which layer.
- Reading across rows
- The list of capabilities is incomplete. Do not read these rows as a chain leading or lagging overall.
Ecosystem & custody
| Product type | Status | Notes and sources |
|---|---|---|
| Automated market makers | ThinQiSwap | QiSwap describes itself as an automated market maker on Qtum built on the Uniswap V2 design, and qtum.org's ecosystem map lists it. Its two liquidity-pool tokens listed on qtum.info had 134 and 139 holders at review. Liquidity depth and recent volume were not measured; the foundation said in May 2026 that third-party studios plan another exchange. 20222931 |
| Issuer-native stablecoins | None found | Neither Tether's supported-protocols page nor Circle's USDC address list includes Qtum. A token named Bridged USDC exists on qtum.info but had no supply and no holders at review. The foundation plans to use Circle's bridged USDC standard once its bridge launches, which would make it a bridge-issued token rather than Circle-issued; the bridge contracts describe a possible later hand-over to Circle. 2030333536 |
| Algorithmic stablecoins | Unknown | The earlier note said absence was not verified, so the rule that absence needs a source makes this unknown. Earlier finding: no algorithmic stablecoin with material usage on Qtum was found in qtum.info's token list or in the foundation's ecosystem map. 2229 |
| Bridges | UnknownQtum Bridge (Qtum to Ethereum) | The Qtum project publishes bridge code and contracts for moving tokens between Qtum and Ethereum, which it says CertiK audited. The foundation's May 2026 update said the bridge would go live in summer 2026; no mainnet launch was confirmed, and the bridged USDC token on qtum.info had no supply at review. Risk: The bridge contract can run in an owner mode controlled by one account or in a signers mode where validator keys meeting a threshold approve withdrawals, and authorised parties can pause deposits and withdrawals and upgrade the contract. Users would trust those key holders rather than either chain's consensus. Who holds the keys and the threshold on mainnet were not found. 2030323334 |
| Block explorers | First-partyqtum.info | qtum.org links qtum.info as its explorer, and the documentation for its API is published in the Qtum project's GitHub organisation. Qtum's exchange guide instead names qtumexplorer.io, which showed a parked for-sale page at review, so that link should not be used. Other explorers were not verified; an explorer's view is provider data, not independent validation. 14222526 |
| Hardware wallets | Established in the ecosystemLedger (Ledger Wallet; Qtum Core or Qtum Electrum for tokens and delegation), Trezor (disputed; Qtum Electrum only) | See the custody section. Ledger's Qtum page names its Ledger Wallet app and Ledger Wallet's current source code lists Qtum; Qtum Core adds token sends and delegation with a Ledger. Trezor's Qtum page says it does not support Qtum even though its firmware support list includes QTUM. Qtum's docs describe staking only from an online, unlocked Qtum Core wallet, so hardware-wallet holders take part through delegation to a super staker. 112137383940 |
Hardware-wallet custody
| Device maker | Status | What users can and cannot do |
|---|---|---|
| Ledger | Native supportSame as native: Yes | Can: Add a QTUM account and send or receive QTUM in Ledger Wallet: Ledger's Qtum page points to the Ledger Wallet app, and Ledger Wallet's current source code lists Qtum among its Bitcoin-family coins Can: Use the Qtum device app with Qtum Core for QRC20 token sends, on-device address checks and delegation to a super staker, per the Qtum Core 25.1 release notes Can: Use the device with Qtum Electrum, including delegation, per Qtum's docs Cannot: Stake from the device itself: Qtum's docs describe staking only from an online, unlocked Qtum Core wallet, so a Ledger holder takes part by delegating to a super staker Cannot: Manage QRC20 tokens or delegation inside Ledger Wallet itself: no Ledger source reviewed says it can, and Qtum's own wallets are the documented routeLedger's Qtum page mixes current text naming the Ledger Wallet app with dated technical text (it presents the x86 machine as due at the end of 2019), and its staking section points to Qtum Core or Qtum Electrum. Since a June 2026 change, Ledger Wallet treats a coin as supported when it appears in a coin module's list, and Qtum is in the Bitcoin-family list. The Ledger Wallet route was not tested. 111216213738 |
| Trezor | Through an intermediaryQtum Electrum (Qtum's light desktop wallet)Same as native: No | Can: Use a Trezor with Qtum Electrum, which Qtum's download page says supports Trezor and whose release notes include a Trezor connection fix; Trezor's firmware support list includes QTUM for all current models Cannot: Manage QTUM in Trezor Suite; Trezor's Qtum page says Trezor does not support Qtum Cannot: Stake from the device itself; staking runs in an online, unlocked Qtum Core walletVendor sources disagree: the Trezor website says Qtum is unsupported while the firmware's support file lists it. The Qtum Electrum route was not tested and its latest release is from late 2023. 1123243940 |
Public data
iKnow Blockchain has no public-data lookups for Qtum yet. This is a limit of the service, not a statement about the network.
| Lookup | Status | What it covers and its limits |
|---|---|---|
| Address or account | Not available yet | Public-data lookups for this chain are not built yet. |
| Tokens and assets | Not available yet | Public-data lookups for this chain are not built yet. |
| NFTs | Not available yet | Public-data lookups for this chain are not built yet. |
| Transactions | Not available yet | Public-data lookups for this chain are not built yet. |
Sourced developments
Developments: Review overdue Reviewed Sep 27, 2026; next review was due Oct 7, 2026, 12:00 UTC.
Publication date · newest first
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Qtum Core v30.2 released
Qtum Core v30.2 rebased the node on Bitcoin Core 30.2. The notes list faster start-up by loading and verifying snapshots of the unspent-output set, encrypted peer connections as an option, the move to Qt 6 and wallets that must use the newer descriptor format. The release is not labelled a hard fork.
- Implementation:Released
- Release:released 2026-07-22
- Activation:no activation height stated
Source: Qtum project — Qtum Core v30.2 - Upgrade to bitcoin core v30.2 (external site)
-
Foundation plans Qtum to Ethereum bridge and bridged USDC
The Qtum Foundation said its Ethereum bridge, a MetaMask Snap and Circle's bridged USDC contracts were audited and expected to launch in summer 2026, with a third-party exchange and other apps to follow later in the year.
- Proposal:Announced
- Implementation:code and audits described by the foundation
- Release:expected summer 2026
- Activation:not confirmed at review
Sources: Qtum Blog — Qtum Development Updates for 2026 (external site) · Qtum project — Qtum Bridge (bridge-core README) (external site) · qtum.info — qtum.info token page: Bridged USDC (USDC.e) (external site)
-
Second QTUM subsidy halving
The block subsidy fell from 0.5 to 0.25 QTUM at block 5,369,004 on 30 November 2025, as scheduled in the consensus code. The foundation puts new issuance at roughly 0.25% a year afterwards and expects the next halving around December 2029.
- Implementation:built into consensus rules
- Release:not applicable
- Activation:took effect at block 5,369,004
Sources: qtum.info — qtum.info block 5,369,004 (external site) · Qtum project — Qtum Core block validation (src/validation.cpp) (external site) · Qtum Blog — Qtum Development Updates for 2026 (external site)
-
Qtum Core v29.1 hard fork released
Qtum released Qtum Core v29.1, a mandatory hard fork that rebased the node on Bitcoin Core 29.1 and added Pectra-era contract features, including a BLS12-381 precompile and a contract for looking up older block hashes. It activated at block 5,483,000, which the explorer dates to 12 January 2026.
- Implementation:Released
- Release:released 2025-11-04
- Activation:activated at block 5,483,000 on 2026-01-12
Sources: Qtum project — Qtum Core v29.1 - Hard Fork - Upgrade to bitcoin core 29.1 - EVM Pectra (external site) · Qtum Blog — What's Included in the Qtum v29.1 Hard Fork? (external site) · qtum.info — qtum.info block 5,483,000 (external site) · Qtum Blog — Qtum Development Updates for 2026 (external site)
Topics your AI can explain
Your AI can explain these topics for Qtum through the connection, with sources.
Known gaps
What this profile's review did not establish:
- No throughput figure was classified; the numbers on Ledger's Qtum page and QiSwap's site have no stated method.
- Staking concentration comes from one day of explorer data (26 September 2026); addresses were not mapped to operators and the sample was not repeated.
- Who holds voting rights in the on-chain parameter governance contracts today, and whether a vote has changed Qtum Core's default block size, gas limit or minimum gas price, was not verified; qtum.org's technology page still lists 2 MB blocks.
- Whether the Qtum to Ethereum bridge and bridged USDC are live on mainnet, and who holds the bridge validator keys, could not be confirmed.
- QiSwap liquidity, recent volume and whether its app is still maintained were not measured.
- Whether Qtum Electrum (latest release late 2023) still works after the 2025 and 2026 hard forks, and what its light-client mode verifies, was not checked.
- Trezor support is disputed between Trezor's website and its firmware support file and was not tested.
- Current chain size, bandwidth needs and initial sync time for a full node were not measured.
- Explorers other than qtum.info and third-party bridges or wrapped QTUM on other chains were not reviewed.
- Whether the testnet Lightning client is still maintained was not checked.
- The Ledger Wallet route for QTUM rests on Ledger's page and Ledger Wallet's source code and was not tested; no Ledger source said Ledger Wallet handles QRC20 tokens or delegation.
Sources
Oldest dated source check: Source checked Sep 27, 2026 Next check due Oct 27, 2026.
- Qtum Core chain parameters (src/kernel/chainparams.cpp) (external site)
- Qtum Core block validation (src/validation.cpp) (external site)
- Qtum Core sync checkpoint logic (src/node/blockstorage.cpp) (external site)
- Qtum Core proof-of-stake kernel (src/pos.cpp) (external site)
- Qtum Core chain work (src/chain.cpp) (external site)
- Qtum Core contract VM versions (src/qtum/qtumtransaction.h) (external site)
- Qtum Core governance parameter defaults (src/qtum/qtumDGP.cpp) (external site)
- Qtum Core block header (src/primitives/block.h) (external site)
- Qtum Core contract state and contract-output root (src/qtum/qtumstate.h) (external site)
- Qtum Blockchain New Whitepaper (external site)
- Qtum Staking (external site)
- Offline Staking (external site)
- Differences between EVM chains (external site)
- Guidance for Exchange Deployment (external site)
- Qtum Lightning Network (external site)
- Electrum (Qtum Electrum user guide) (external site)
- Staking with a Raspberry Pi (external site)
- Staking with a VPS (external site)
- Understanding Staking on Qtum (external site)
- Qtum Development Updates for 2026 (external site)
- Qtum Core v25.1 release notes (external site)
- About Qtum (external site)
- Download Qtum Wallet (external site)
- Qtum Electrum releases (external site)
- qtum.info explorer (external site)
- qtuminfo-api: qtuminfo API documentation (external site)
- qtum.info blocks for 26 September 2026 (UTC) (external site)
- qtum.info block 6,179,449 (delegated block example) (external site)
- qtum.info QRC20 token list, page 2 (external site)
- qtum.info token page: Bridged USDC (USDC.e) (external site)
- QiSwap (external site)
- Qtum Bridge (bridge-core README) (external site)
- Bridge EVM Contracts README (external site)
- Qtum Wallet (MetaMask Snap) README (external site)
- Supported protocols (external site)
- USDC contract addresses (external site)
- Qtum Wallet - Buy, manage & hold your QTUM (external site)
- Ledger Wallet coin module loaders (libs/ledger-live-common/src/coin-modules/loaders.ts) (external site)
- Qtum coin page (external site)
- Trezor firmware coin support list (common/defs/support.json) (external site)
Report an error
Found something wrong or out of date? Reporting is free, and every chain goes through the same process. Published corrections appear in the public log.
Funding disclosure
Funding disclosures appear here when an upkeep arrangement exists, in the form “Upkeep funded by [name]; verdicts unaffected.” The funder ledger has not been published yet. Neutrality & funding