Fungible Token

Simple fungible token with fixed or unlimited supply and configurable mint/transfer approvals

Category: Token Types

Summary

Required standards: ["Fungible Tokens"]

• validTokenIds: MUST be exactly [{ "start": "1", "end": "1" }] (single token ID)

• All tokens share the same token ID (1), making them interchangeable

• Amount field in transfers determines quantity

• Token metadata must reference token ID 1

• Ownership times typically forever: [{ "start": "1", "end": "18446744073709551615" }]

Instructions

Fungible Token Configuration

When creating a fungible token collection, you MUST follow these requirements:

Required Configuration

1. validTokenIds: Set to exactly [{ "start": "1", "end": "1" }]

   • This ensures only token ID 1 is valid

   • This is the standard pattern for fungible tokens

2. Standards: Include "Fungible Tokens" in the standards array

   • Example: "standards": ["Fungible Tokens"]

3. Token Metadata: Each tokenMetadata entry must reference token ID 1

   • Example: "tokenIds": [{ "start": "1", "end": "1" }]

Supply Tracking with approvalAmounts

Fungible tokens use approvalAmounts (NOT predeterminedBalances) to track minting supply:

{
  "approvalCriteria": {
    "overridesFromOutgoingApprovals": true,
    "approvalAmounts": {
      "overallApprovalAmount": "1000000",
      "perInitiatedByAddressApprovalAmount": "1000",
      "perToAddressApprovalAmount": "0",
      "perFromAddressApprovalAmount": "0",
      "amountTrackerId": "mint-tracker",
      "resetTimeIntervals": { "startTime": "0", "intervalLength": "0" }
    }
  }
}

• overallApprovalAmount: total supply cap (use "0" for unlimited)

• perInitiatedByAddressApprovalAmount: max per user (use "0" for unlimited)

• IMPORTANT: predeterminedBalances and approvalAmounts are INCOMPATIBLE — fungible tokens use approvalAmounts, NOT predeterminedBalances

Pattern-Specific Gotchas

• All tokens share the same token ID (1), making them interchangeable

• Amount field in transfers determines quantity (e.g., "amount": "100" means 100 tokens)

• Ownership times are typically forever: [{ "start": "1", "end": "18446744073709551615" }]

Common Mistakes

• DON'T use predeterminedBalances for fungible tokens — use approvalAmounts instead. They are incompatible.

• DON'T use numbers instead of strings for amounts — use "1000" not 1000. All numeric values must be string-encoded.

• DON'T forget autoApproveAllIncomingTransfers: true in defaultBalances — without it, recipients cannot receive tokens on public-mint collections.

• DON'T forget overridesFromOutgoingApprovals: true on Mint approvals — required for all fromListId: "Mint" approvals.

• DON'T use multiple token IDs — fungible tokens must use exactly one token ID [{ "start": "1", "end": "1" }].

Example Structure

{
  "updateValidTokenIds": true,
  "validTokenIds": [{ "start": "1", "end": "1" }],
  "updateStandards": true,
  "standards": ["Fungible Tokens"],
  "updateTokenMetadata": true,
  "tokenMetadata": [{
    "uri": "ipfs://...",
    "customData": "",
    "tokenIds": [{ "start": "1", "end": "1" }]
  }]
}