Advanced Token Features

Beyond standard ERC-20 and ERC-721, Urblock supports specialized token standards for specific use cases.

SBT — Soulbound Tokens (EIP-5192)

Non-transferable tokens bound to a single address. Useful for credentials, certifications, and reputation.

const sbt = await urblock.tokens.create({
  name: "Developer Certificate",
  symbol: "CERT",
  standard: "SBT",
  network: "polygon_amoy",
  features: { mintable: true, burnable: true },
  idempotency_key: "sbt-001",
});

Key Properties

• locked() always returns true
• Transfers are blocked by _update() override (except mint and burn)
• Supports supportsInterface(IERC5192) — 0xb45a3c0e
• Enumerable, URI storage, pausable

Mint a Credential

const tx = await urblock.transactions.mint(sbt.id, {
  to: "0xRecipient...",
  amount: "1",
  token_uri: "ipfs://QmCredential.../metadata.json",
  idempotency_key: "mint-cert-001",
});

ERC-1363 — Payable Tokens

Tokens that trigger a callback on the receiver when transferred. Enables "approve and call" in a single transaction.

const payable = await urblock.tokens.create({
  name: "Payable Token",
  symbol: "PAY",
  standard: "ERC1363",
  network: "polygon_amoy",
  initial_supply: "1000000000000000000000000",
  idempotency_key: "erc1363-001",
});

Use Cases

• Payment for services in a single transaction
• Token-gated actions without separate approval
• Automated subscription payments

Solady Gas-Optimized Variants

All three base standards have Solady variants with identical ABI but ~40-50% lower gas costs:

Standard	Solady Variant	Gas Savings
ERC-20	ERC20_SOLADY	~40%
ERC-721	ERC721_SOLADY	~45%
ERC-1155	ERC1155_SOLADY	~50%

const optimized = await urblock.tokens.create({
  name: "Efficient Token",
  symbol: "EFF",
  standard: "ERC20_SOLADY",
  network: "polygon_amoy",
  initial_supply: "1000000000000000000000000",
  idempotency_key: "solady-001",
});

Complete Standards Reference

Standard	Type	Key Feature
ERC20	Fungible	Standard fungible token
ERC20_VOTES	Fungible	Governance voting delegation
ERC721	NFT	Standard non-fungible token
ERC1155	Multi	Fungible + non-fungible in one contract
ERC3643	Security	T-REX with compliance enforcement
SBT	NFT	Non-transferable (soulbound)
ERC1363	Fungible	Callback on transfer (payable)
ERC20_SOLADY	Fungible	Gas-optimized ERC-20
ERC721_SOLADY	NFT	Gas-optimized ERC-721
ERC1155_SOLADY	Multi	Gas-optimized ERC-1155

Next Steps

• Token Standards — detailed standard comparison and decision tree
• Deploy Your First Token — get started with any standard
• Gas Optimization — Solady and batch strategies
• Security Tokens — T-REX compliance setup