Layer 1 blockchain
Sia ticker SC
Summary
Sia mainnet has run since June 2015 as a proof-of-work chain whose ledger funds storage agreements between renters and hosts. Miners grind a nonce until the BLAKE2b hash of the block header is below the current target; since the 2018 ASIC hardfork at block 179,000 the nonce must also be a multiple of 1009. Blocks target 10 minutes, and a continuous rule called Oak adjusts difficulty every block. The v2 hardfork was allowed from block 526,000 (6 June 2025) and required from block 530,000; it moved unspent outputs into a Merkle accumulator, which Sia calls Utreexo-based, committed in each block header. The Final Cut hardfork at block 552,100 (scheduled for about 1 December 2025) corrected the v2 difficulty adjustment and removed deprecated fields. 4591012192122
Design
- System
- Layer 1 blockchainIndependent proof-of-work base chain; it does not settle to another chain. Its transactions carry siacoin and siafund outputs, file contracts between renters and hosts, storage proofs and signed attestations such as host announcements. The stored data itself stays off chain with hosts.
- Settlement family
- Its own design
- Scarce resource
- Work (proof of work)
- State model
- UTXO
- Finality
- Probabilistic
- Who makes blocks
- Miners, alone or through pools, assemble blocks from the transaction pool and grind nonces; the Foundation's December 2025 upgrade tracker listed f2pool, DxPool and Luxor. The miner's single payout is the block reward, 30,000 SC per block since block 270,000, plus fees. A separate Foundation subsidy of 30,000 SC per block is paid to a Sia Foundation address every 4,380 blocks. Every full node checks each block against the consensus rules in the Foundation's core library.
- Fork choice
- Nodes follow the valid chain with the most total work. The reference code switches to a competing chain only when it has more work than the current chain plus a fifth of the current difficulty, a node policy against timestamp games that the code marks as not a consensus rule. Confirmations add confidence but never make a block final. Miner payouts, Foundation subsidies, siafund claims and contract payouts stay locked for 144 blocks (about a day) so shallow reorganizations do not strand spends that depend on them.
Qualifications
- Settlement family · Partial. Recorded as other. Sia's own terms: an independent proof-of-work chain whose consensus rules live in the Sia Foundation's Go libraries, core and coreutils, which walletd, hostd, renterd, indexd and the explored explorer build on. The v2 upgrade rewrote the codebase from scratch.
- Element accumulator · Applies. Sia's own terms for its state: siacoin, siafund, file contract, attestation and chain-index elements held in an element accumulator, a Merkle tree that Sia describes as Utreexo-based. A transaction carries the full element it spends plus a Merkle proof, so nodes keep only a few root hashes and each wallet keeps proofs for its own outputs. Spent elements are marked, not deleted.
- Siafunds · Applies. Siafunds are a second native asset with a fixed supply of 10,000. Since v2, 4% of each new file contract's value accrues to siafund holders in proportion to holdings and is paid in siacoins when a siafund output is spent. Sia's hosting guide still states the older rate of 3.9%; the learn pages and consensus code give 4% for v2 contracts.
- Foundation subsidy · Applies. Since the February 2021 Foundation hardfork, consensus creates 30,000 SC per block for a Sia Foundation address, paid as one output every 4,380 blocks, after a one-time initial output of about 1.58 billion SC. Sia's learn page says both Foundation addresses are controlled by multisig and the failsafe address has a timelock.
- Storage proofs · Applies. Consensus checks one storage proof per contract, after the proof height and before expiration: a Merkle proof for one 64-byte leaf chosen from the ID of the block at the proof height. A contract that expires without a proof pays the host only its missed value, and the difference is destroyed. The proof shows the host could produce that leaf then; it does not show availability during the contract.
- Throughput · Unknown. No primary-source transaction-rate figure was classified. Blocks are limited by encoded weight and a ten-minute target, not by a published rate.
Tradeoffs
- Emphasizes
- Decentralization and Security
- Gives up
- Base-layer capacity and fast settlement: blocks arrive about every 10 minutes under a fixed block weight cap, confirmations never become final, and block payouts mature only after 144 blocks. The chain carries contracts, revisions and storage proofs, while stored data and its transfer stay off chain with hosts, so storage performance depends on the host market and client software, not on block space.Security rests on ASIC proof-of-work mining; pool and hashrate concentration were not measured here. The v2 state design lets a node validate new blocks without keeping the full set of unspent outputs, which lowers the cost of running a node, but wallets must keep Merkle proofs for their own outputs up to date. Sia's history includes contested hardforks, such as the 2018 nonce rule that disabled some ASIC models then in use.
- Full node at home
- Practical at home 3182024272838The Foundation's downloads page lists a quad-core processor, 8 GB of RAM and a 256 GB SSD for walletd, and adds a 4 TB hard drive for stored data for hostd. The Foundation also said the December 2025 upgrade would cut a node's disk footprint to about 200 MB and full sync to about an hour; none of these figures was measured here. Since v2 a node can instant-sync from a checkpoint and then validate every later block, and hostd can prune old blocks (keeping at least 144 is advised). A host also needs disks, bandwidth and near-constant uptime, which validation alone does not.
- Throughput claims
- No classified figure recorded
Scaling layers
- File contract payment channels (renter-host protocol) · Payment channels, mainnet 31623
Sia describes each file contract as a two-way payment channel between one renter and one host. Both lock siacoins on chain; revisions that move payment to the host and update the data's Merkle root are signed off chain, and only a revision with a higher number can replace an earlier one. At the end the host posts a storage proof to collect, or forfeits collateral. It pays for storage between two parties and is not a general payment network.
Capabilities
| Capability | How it is provided | Notes and sources |
|---|---|---|
| Account abstraction | Structured assessment pending | Not yet assessed for any chain. |
| Atomic swaps | Built into the protocolLimited scope | Protocol, limited to the same chain: a v2 transaction can spend outputs held under different spend policies, each input signing a hash of the whole transaction, and consensus requires siacoin and siafund inputs to equal outputs, so two parties can exchange siacoins for siafunds in one transaction that is valid in full or not at all (inferred from the transaction rules; no tool doing it was reviewed). Across chains, the SHA-256 hash-preimage policy, which Sia's docs say was chosen for cross-chain atomic swaps, and height and time locks are building blocks; no cross-chain swap tool was found. 10141522 |
| Authenticated data publication | Built into the protocolLimited scope | Protocol: attestations are a built-in transaction element, a key and value signed by a public key and kept in the accumulator that each header commits to. Sia's docs say a light client can fetch any subset from a peer or explorer and check it by multiproof, with the attestation count preventing omission. Limited: values ride in blocks under the weight cap, and reading a newer attestation for the same key as an update is a convention, not a consensus rule. 13171823 |
| Light clients | Built into the protocolLimited scope | Protocol, limited: proof of work can be checked from headers alone, and since v2 each header commits to the compact parent state, so a node can verify a checkpoint's state against its header and then fully validate every later block (hostd's instant sync). Limits: the checkpoint hash must come from a trusted source or a header-chain sync, a wallet cannot skip its own history, hostd labels instant sync experimental, and no light wallet that checks proofs against headers was found; the lite web wallet in Sia's docs relies on its operator's servers. 813182027 |
| 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 | Native (protocol or core-team software) Earlier definition | Each file contract is a two-way payment channel between a renter and a host built into consensus: off-chain revisions move payment and update the data root, and the channel closes by renewal, storage proof or expiration. It serves storage payments between two parties; no general payment channel network was found. 1623 |
| Programmable spending | Native (protocol or core-team software) Earlier definition | v2 spend policies set output conditions: an Ed25519 signature, a SHA-256 hash preimage, a height or time lock, and threshold combinations of these. An address is the hash of its policy, revealed when spent. File contracts are a separate built-in type. There is no general-purpose contract execution or contract storage. 141516 |
| Protocol-verified messaging | Structured assessment pending | Not yet assessed for any chain. |
| Reversible transfers or recovery | Unknown | Building blocks only: threshold spend policies combined with height or time locks could express delayed or backup spending paths, but no wallet offering a sender-reclaim window or a pre-arranged recovery path was shown live on mainnet in the reviewed sources. 15 |
| Rollups | Unknown | No rollup settling to Sia was found in the reviewed sources. Sia's transactions carry outputs, file contracts, attestations and arbitrary data, with no general program execution that could verify rollup proofs; absence was not exhaustively verified. 14 |
| Shielded transfers | Structured assessment pending | Not yet assessed for any chain. |
| Signed partial offers | Not present | Nearest feature: v2 input signatures cover a hash of the whole transaction, so a maker cannot sign one side for any taker to complete, and spend policies check only signatures, hash preimages, time locks and thresholds, so an output cannot demand a payment in return. The v1 option to sign only chosen fields ended once v2 blocks became required, and the only on-chain assets are siacoins and siafunds. 10131522 |
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 | None found | Sia's transactions carry only siacoin and siafund outputs, file contracts, attestations, arbitrary data, a Foundation address update and a miner fee, and spend policies check only signatures, hash preimages, time locks and thresholds, so no pooled market maker can run on Sia's ledger. Siacoin trades on exchanges off chain. 11415 |
| Issuer-native stablecoins | None found | The ledger holds only two assets, siacoins and siafunds, and transactions cannot create others. Neither Circle's USDC address list nor Tether's supported-protocol list includes Sia. 10143334 |
| Algorithmic stablecoins | None found | Only siacoins and siafunds exist on the ledger, and transactions can neither change their total supply nor issue other tokens, so no algorithmic stablecoin can be issued on Sia itself. 1014 |
| Bridges | Unknown | No bridge or wrapped form of siacoin was reviewed. Sia's spend policies check only signatures, hash preimages and time locks, so the chain cannot itself verify another chain's state. Risk: Any wrapped siacoin on another chain would depend on its issuer or bridge operators, not on Sia consensus; none was verified here. 15 |
| Block explorers | First-partySiaScan (Sia Foundation), SiaGraph | SiaScan's site footer names the Sia Foundation, and its API is the default explorer service in the Foundation's hostd software. Sia's community page lists SiaScan and SiaGraph, a separate network-statistics site whose operator was not identified. Explorer data is provider-indexed, not independent validation. 2729303132 |
| Hardware wallets | ThinLedger (Sia device app through walletd or Sia Central), Cypherock X1 (per a Foundation grant report) | See custody rows: Ledger devices sign through a Sia device app with walletd or Sia Central's web wallet, not inside Ledger's own wallet app, and Trezor states it does not support Siacoin. A Foundation recap reported in December 2025 that a grant-funded Cypherock X1 integration had shipped; the vendor's own pages were not verified. 78263537 |
Hardware-wallet custody
| Device maker | Status | What users can and cannot do |
|---|---|---|
| Ledger | Through an intermediarywalletd or Sia Central's web wallet, signing with the Sia app on the Ledger deviceSame as native: Unknown | Can: Install the Sia app on a Ledger device from Ledger Live's app catalog and sign Siacoin transactions through Sia Central's web wallet, per Sia's guide Can: Add a Ledger wallet in walletd, which the Foundation's docs say supports Ledger hardware wallets Cannot: Find Siacoin in Ledger's published Ledger Wallet currency list (@ledgerhq/cryptoassets 13.56.0) Cannot: Send siafunds or claim siafund dividends through Sia Central's web wallet, which Sia's guide says supports Siacoin onlyThe Sia device app's source, a fork of the Sia Foundation's development repository, is published in Ledger's GitHub organization and includes v2 transaction code. In its June 2025 update the Foundation said walletd's Ledger path used blind signing as an interim step until Ledger added native v2 support; whether that still applies was not verified. 78253536 |
| Trezor | None foundSame as native: No | Cannot: Manage Siacoin with a Trezor; Trezor's Siacoin page says Trezor does not currently support itTrezor's page asks users who used Siacoin with Trezor before to contact support. Third-party signing paths using a Trezor were not checked. 37 |
Public data
iKnow Blockchain has no public-data lookups for Sia 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: Reviewed Sep 29, 2026 Next review due Oct 9, 2026, 12:00 UTC.
Publication date · newest first
-
Sia Storage mobile app launched on iOS and Android
The Foundation's May 2026 recap reports that the Sia Storage mobile app launched for iOS and Android at Consensus Miami, with a free storage allowance. The app encrypts and erasure-codes data on the device and uses the Sia Storage hosted indexer to manage contracts with hosts.
- Implementation:apps released
- Release:launched on iOS and Android per the Foundation's recap
- Activation:available per the Foundation; not tested in this review
Sources: Sia Foundation blog — The State of Sia, May 2026 (external site) · The Sia Storage Company — Sia Storage (external site) · Sia Foundation (Sia Docs) — About Storing Data on Sia (external site)
-
Renter-host protocol gained shared account pools
core v0.21.0 added pool RPCs to the renter-host protocol, letting a renter fund one shared pool that many accounts draw on, so each account need not be funded separately. hostd v2.9.0 (2026-06-03) added host-side support, and indexd v0.3.0 (2026-06-30) switched apps to one pool per connect key. This is a change to the off-chain protocol between renters and hosts, not to consensus.
- Implementation:shipped in core v0.21.0, hostd v2.9.0 and indexd v0.3.0
- Release:Released
- Activation:available when both the renter's and the host's software support it; no network activation
Sources: Sia Foundation (GitHub) — core v0.21.0 release notes (external site) · Sia Foundation (GitHub) — hostd v2.9.0 release notes (external site) · Sia Foundation (GitHub) — indexd v0.3.0 release notes (external site) · Sia Foundation (GitHub) — core CHANGELOG (external site) · Sia Foundation blog — The State of Sia, May 2026 (external site)
-
hostd v2.7.0 added optional consensus pruning
hostd v2.7.0 added an experimental, off-by-default option that limits how many blocks a host stores, since the v2 state design no longer needs every past block to validate new ones. The release advises keeping at least one day of blocks (144 on mainnet) for protection against deep reorganizations. It also fixed contracts wrongly shown as active when a revision and resolution landed in the same block.
- Implementation:shipped in hostd v2.7.0
- Release:released as an experimental option, off by default
- Activation:opt-in per host
Sources: Sia Foundation (GitHub) — hostd v2.7.0 release notes (external site) · Sia Foundation blog — The State of Sia, February 2026 (external site)
-
Instant sync reached hostd (v2.6.0) and walletd (v2.12.0)
hostd v2.6.0 added instant sync: a new host can start from a checkpoint whose compact state is committed in the block header and fully validate blocks from there, without replaying the whole chain. walletd v2.12.0 followed on 2026-02-12 with a checkpoint option for the same purpose. hostd's notes say the host's wallet must have only v2 history to use it.
- Implementation:shipped in hostd v2.6.0 and walletd v2.12.0
- Release:released; hostd's README labels it experimental
- Activation:opt-in per node; no network activation
Sources: Sia Foundation (GitHub) — hostd v2.6.0 release notes (external site) · Sia Foundation (GitHub) — walletd v2.12.0 release notes (external site) · Sia Foundation — Learn / Consensus / Instant Syncing (external site) · Sia Foundation blog — The State of Sia, January 2026 (external site) · Sia Foundation (GitHub) — hostd repository (external site)
-
Final Cut hardfork scheduled for block 552,100 to fix v2 difficulty and remove deprecated fields
The Sia Foundation announced a network upgrade, codenamed V2: The Final Cut, for block 552,100, estimated for the first week of December 2025. It closes out the v1 era by removing deprecated fields, fixes the v2 difficulty adjustment and prepares for parallel and instant syncing. All active nodes had to run walletd v2.11.0, hostd v2.4.0, renterd v2.7.0, minerd v0.3.2 or later to stay in consensus.
- Proposal:scheduled by the Sia Foundation
- Implementation:shipped in walletd v2.11.0, hostd v2.4.0, renterd v2.7.0 and minerd v0.3.2
- Release:supported versions released before the fork
- Activation:activated at consensus height 552,100, whose block SiaScan shows timestamped 2 December 2025; Sia's hardfork history describes it as deployed
Sources: Sia Foundation blog — V2 - The Final Cut: Network Upgrade Scheduled for December (external site) · Sia Foundation (Sia Docs) — V2: The Final Cut - Network Upgrade (December 2025) (external site) · Sia Foundation (GitHub) — coreutils chain/network.go: mainnet parameters and hardfork heights (external site) · Sia Foundation — Learn / Consensus / Hardforks (external site) · Sia Foundation (SiaScan) — SiaScan explorer API: consensus state (external site) · Sia Foundation (SiaScan) — SiaScan: Block 552,100 (external site)
Topics your AI can explain
Your AI can explain these topics for Sia through the connection, with sources.
Known gaps
What this profile's review did not establish:
- Mining pool shares and hashrate distribution were not measured; the Foundation's December 2025 upgrade tracker named three upgraded pools but not their shares.
- The Foundation's listed system requirements and its footprint and sync-time figures (from its October 2025 recap) were not measured on a running node.
- The current coreutils mainnet parameters include a further consensus height, 583,000, added on 3 July 2026 alongside coordinated core, walletd, hostd and explored releases. From it the consensus code applies stricter checks to outputs spent in the block that created them and to contract revisions, and SiaScan shows block 583,000 timestamped 7 July 2026. No announcement explaining it was found, so it is not described as a hardfork here.
- Sia's hosting guide still gives the v1 siafund rate of 3.9% while the learn pages and consensus code give 4% for v2 contracts; the guide appears outdated.
- No fee schedule was found and the reviewed consensus code sets no minimum fee; typical fees and the transaction pool's fee policy were not verified.
- Whether Ledger's Sia app still needs blind signing for v2 transactions was not tested, and no Ledger vendor page for Siacoin was found.
- The Cypherock X1 integration is reported only in a Foundation grant recap; the vendor's own support pages were not verified.
- Wrapped or bridged forms of siacoin on other chains were not reviewed.
- No cross-chain atomic swap tool or recovery-path wallet was found, and no tool for same-chain siacoin-for-siafund swaps was reviewed; absence was not exhaustively verified.
- Whether readers of shared Sia objects can check downloads against a root the chain records was not verified; data publication is assessed on attestations.
- Sia Central's operator was not identified, and its lite wallet relies on its own servers for chain data.
- The Foundation's July 2025 recap dates the v2 fork's completion to 3 July 2025 and the parameter file estimated 4 July, while SiaScan shows block 530,000 timestamped 30 June 2025; the reason for the difference was not found.
- Siafund ownership distribution was not reviewed.
- Host counts, stored data and host concentration were not measured from the chain; third-party dashboards were not used for the assessment.
- No throughput figure was classified from a primary source.
- No light wallet that checks Sia proofs against block headers was found; light verification is assessed on instant sync, which hostd labels experimental.
Sources
Oldest dated source check: Source checked Sep 29, 2026 Next check due Oct 29, 2026.
- Learn about Siacoins (external site)
- Which Sia software do I need? (external site)
- About Providing Storage on Sia (external site)
- core types/hash.go (master): BLAKE2b-256 hashing used for block IDs (external site)
- V2: The Final Cut - Network Upgrade (December 2025) (external site)
- Siacoin Total Supply (external site)
- Your Sia Wallet (walletd) (external site)
- Sia Ledger app with Sia Central (external site)
- Learn / Consensus / Work (difficulty and the Oak adjustment) (external site)
- Learn / Consensus / Outputs (external site)
- Learn / Blocks and Transactions / Siafunds (external site)
- Learn / Consensus / Hardforks (external site)
- Learn / Blocks and Transactions / Blocks (external site)
- Learn / Blocks and Transactions / Transactions (external site)
- Learn / Blocks and Transactions / Spend Policies (external site)
- Learn / Blocks and Transactions / File Contracts (external site)
- Learn / Blocks and Transactions / Attestations (external site)
- Learn / Consensus / State (external site)
- Learn / Consensus / Accumulator (external site)
- Learn / Consensus / Instant Syncing (external site)
- coreutils chain/network.go (master): mainnet parameters and hardfork heights (external site)
- core consensus/state.go (master): fork-choice threshold, block reward, subsidy, weight and signature hashes (external site)
- core types/types.go (master): outputs, file contracts, storage proofs and attestations (external site)
- The State of Sia, October 2025 (external site)
- The State of Sia, June 2025 (external site)
- The State of Sia, November 2025 (external site)
- hostd repository README (instant sync and default explorer API) (external site)
- hostd v2.7.0 release notes (experimental consensus pruning) (external site)
- Sia community ecosystem directory (external site)
- siascan: block explorer with host statistics (external site)
- SiaScan explorer API: consensus state (read 2026-09-29, height 595,169) (external site)
- SiaGraph network statistics (external site)
- USDC contract addresses (external site)
- Supported protocols (external site)
- @ledgerhq/cryptoassets 13.56.0 currency list (external site)
- app-sia: Sia wallet app for Ledger devices (external site)
- Siacoin wallet (external site)
- Sia Software Downloads (system requirements for indexd, hostd and walletd) (external site)
- SiaScan: Block 530,000 (v2 require height) (external site)
- V2 - The Final Cut: Network Upgrade Scheduled for December (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