Reading the map
Bitcoin sits at the base, everything above it is a compromise on a single axis: how much you trust something other than Bitcoin itself.
Edge legend
Native / trust-minimized
Federated / multi-sig peg
Lightning connection
Cryptographic peg
Layer 1 · Settlement
Bitcoin
The ledger everything else anchors to.
All layers above inherit (somehow) their security from the way they interact with the Bitcoin blockchain. Every L2 is a bet on how to scale, privatize, or program around Bitcoin's deliberately conservative base layer without compromising the settlement guarantee beneath them.
Read more about Bitcoin →
- Role
- Base layer. Proof-of-work. Final settlement.
- Consensus
- Nakamoto · Proof-of-Work (SHA-256)
State Channel
Lightning
Off-chain payments, on-chain settlement.
Lightning allows parties to make payments in satoshis without broadcasting each transaction, settling only the net result back to Bitcoin. Trust is minimized: either counterparty can unilaterally close a channel and reclaim funds on L1 without permission.
Read more about Lightning →
- Role
- Payment channels for instant, low-fee BTC.
- Consensus
- Bilateral payment channels · HTLCs · onion routing
- Bridge
- Native - funded by on-chain multisig UTXO
Peg mechanism
BTC UTXO
2-of-2 Funding Tx
Channel
Lightning Payment
Federated Sidechain
Liquid
Confidential transactions, 2 minutes block time.
Liquid is a production federated sidechain optimized for token issuers. It trades Bitcoin's decentralisation for throughput and confidentiality: the functionary federation holds pegged BTC and signs off on block production.
Read more about Liquid →
- Role
- Federated sidechain.
- Consensus
- Strong Federation · 15 functionaries · 1-min blocks
- Bridge
- Federated peg - 11-of-15 signers custody
Peg mechanism
BTC
Federation Peg-in
L-BTC
Liquid Network
Federated Sidechain
Rootstock
Smart contracts, secured by Bitcoin hashrate.
Rootstock (RSK) runs a Solidity-compatible EVM as a sidechain, merge-mined by a majority of Bitcoin hashrate. The PowPeg bridges BTC to RBTC using a hybrid federation whose HSMs release funds only on proof of sufficient cumulative work.
Read more about Rootstock →
- Role
- EVM-compatible merge-mined sidechain.
- Consensus
- Merge-mined PoW + PowPeg federation
- Bridge
- PowPeg - hybrid federation + miner-gated
Peg mechanism
BTC
PowPeg (HSM + Miners)
RBTC
RSK EVM
State Channel
Ark
A virtual UTXO inside a communal round.
Ark batches many users into shared on-chain outputs coordinated by an Ark Service Provider. Users hold "virtual" UTXOs they can spend instantly off-chain and unilaterally redeem on Bitcoin if the ASP misbehaves. No channel liquidity to manage.
Read more about Ark →
- Role
- Shared UTXO protocol for instant BTC.
- Consensus
- ASP-coordinated rounds · shared output tree
- Bridge
- Native - unilateral exit to L1 after timeout
Peg mechanism
BTC
ASP Round Tx
vUTXO
Ark Payment
Rollup
Citrea
EVM execution, verified by BitVM.
Citrea is a zk-rollup that publishes state roots and data availability back to Bitcoin. It leverages BitVM-style verification to allow Bitcoin to reject invalid rollup state without consensus changes. Arbitrary computation, Bitcoin settlement.
Read more about Citrea →
- Role
- Zero-knowledge rollup on Bitcoin.
- Consensus
- ZK rollup · zkEVM · data posted as inscriptions
- Bridge
- BitVM-based optimistic bridge
Peg mechanism
BTC
BitVM Bridge
zkProof
Citrea Rollup
Rollup
BitVM
Any program, verified by challenge.
BitVM is not a chain, it is a research primitive that lets Bitcoin verify arbitrary programs via fraud proofs between a prover and a verifier. It powers the next generation of trust-minimized bridges used by rollups like Citrea.
Read more about BitVM →
- Role
- Optimistic computation on Bitcoin.
- Consensus
- Optimistic fraud proofs · two-party covenants
- Bridge
- It's a mechanism, not a chain - enables trust-minimized pegs
Peg mechanism
Prover
Taproot Script
Challenge
Verifier
State Channel
Spark
A managed Lightning balance inside a shared liquidity pool.
Spark enables users to hold balances backed by Lightning liquidity without managing channels. Payments are automated, and funds remain withdrawable on-chain at any time. The model relies on shared key custody between the user and provider, limiting unilateral control while simplifying the user experience.
Read more about Spark →
- Role
- Abstracted Lightning balance for instant BTC payments.
- Consensus
- Service-provider coordinated liquidity · Lightning routing
- Bridge
- Native - Lightning settlement with on-chain withdrawal
Peg mechanism
BTC
Funding Tx
Lightning Liquidity Pool
Spark Balance
Lightning Payment
Client-side Validation
RGB
Smart contracts that live off-chain.
RGB flips the model: contract state lives with its owners, not on-chain. Bitcoin UTXOs act as single-use seals that commit to off-chain state transitions. Scales without bloating the chain, at the cost of peer-to-peer data exchange.
Read more about RGB →
- Role
- Client-side assets on Bitcoin & Lightning.
- Consensus
- Client-side validation · cryptographic single-use seals (UTXOs)
- Bridge
- Anchored in Bitcoin UTXOs; data kept by users
Peg mechanism
BTC UTXO (seal)
Commitment
Client State
RGB transaction
Chaumian Mint / E-Cash
e-cash
Cashu · Fedimint
Private digital bearer cash issued by a mint backed by BTC.
e-cash systems use Chaumian blind signatures to allow users to hold and transfer Bitcoin-backed tokens privately and instantly. Transactions occur off-chain, with no public trace on Bitcoin or Lightning. Users can redeem tokens for BTC via the issuing mint. Cashu implements a single-operator mint, optimizing simplicity and fast deployment. Fedimint distributes custody across a federation of guardians, reducing single-point trust at the cost of greater coordination complexity.
Read more about e-cash →
- Role
- Private bearer BTC for instant payments.
- Consensus
- Mint-issued tokens · Chaumian signatures
- Bridge
- Redeemable for BTC via mint (often Lightning)
Peg mechanism
BTC
BTC deposit to mint
Ecash Token
Instant private payment
On-chain Inscription
Inscriptions
Ordinals · Runes
Arbitrary data embedded directly inside Bitcoin transactions.
Bitcoin inscriptions store data on-chain using witness space, enabling assets and metadata to be permanently recorded on Bitcoin.
Ordinals attach data (images, text, JSON) to individual satoshis, enabling NFTs and digital artifacts.
Runes define fungible tokens using a UTXO-based model designed to minimize on-chain footprint and reduce indexer complexity.
Read more about Inscriptions →
- Role
- On-chain data and token protocols secured by BTC.
- Consensus
- Bitcoin L1 validation · indexed metadata interpretation
- Bridge
- Native - directly embedded in Bitcoin transactions
Peg mechanism
BTC
BTC transaction
Inscription
Transfer transaction