Supported Chains

BlockHost is chain-agnostic. The blockchain engine is a pluggable component — each engine implements the same interface, and the rest of the system doesn't know or care which chain is running.

Production-Ready

EVM (Ethereum, Polygon, Base, Arbitrum)

• Engine: blockhost-engine-evm
• Wallet: MetaMask or any injected Ethereum provider
• Contracts: Solidity (ERC-721 NFT + subscription manager)
• Signing: secp256k1 (ECDSA)
• Testnets tested: Sepolia

The original engine. EVM-compatible chains share the same contract bytecode — deploy once, works on any EVM chain.

OPNet (Bitcoin L1)

• Engine: blockhost-engine-opnet
• Wallet: OPWallet browser extension
• Contracts: AssemblyScript (OPNet smart contracts via Tapscript)
• Signing: Schnorr / ML-DSA
• Testnets tested: OPNet Signet

Smart contracts on Bitcoin L1 without sidechains or bridges. Subscriptions and NFTs live directly on Bitcoin. Uses OPNet's Tapscript-encoded calldata — valid Bitcoin transactions paying valid fees.

In Development

Cardano

• Engine: blockhost-engine-cardano
• Wallet: Nami, Eternl, Lace (CIP-30 compatible)
• Contracts: Aiken validators
• Signing: Ed25519
• Testnets tested: Preprod

Uses a UTXO-native subscription model inspired by cardano-swaps. Instead of locking funds in a shared contract, each subscriber creates their own UTXO at a validator address. No custody transfer, no UTXO contention. The validator enforces payment collection and cancellation rules through pure math.

NFTs are Cardano native assets — no smart contract needed for the token itself, just a minting policy tied to the subscription validator.

Adding a New Chain

Building an engine requires implementing:

1. Engine manifest (engine.json) — identity, wizard module, finalization steps, constraints
2. Wizard plugin — Flask blueprint for the installer's blockchain configuration page
3. Finalization steps — wallet generation, contract deployment, chain config
4. Monitor — blockchain event watcher that detects new subscriptions
5. CLI tools — bw (wallet ops), ab (addressbook), is (identity predicates), mint_nft
6. Signing page — wallet connect + signature capture for SSH authentication
7. Signup page — subscription purchase flow

See the Building an Engine guide for the full walkthrough.