# ERC-6150: Hierarchical NFTs Source: https://www.eipsfordesigners.com/standards/ERC-6150 Agent brief: https://www.eipsfordesigners.com/standards/ERC-6150/agent.md Machine-readable JSON: https://www.eipsfordesigners.com/api/standards/ERC-6150 Last reviewed: 2026-05-25 Last updated: 2026-05-25 | Field | Value | | --- | --- | | Status | Final | | Chain | both | | Category | NFT Capabilities | | Journey stages | Asset Discovery & Display, Asset Management | | Detailed guide | Yes | | Official specification | https://eips.ethereum.org/EIPS/erc-6150 | | Discussion search | https://ethereum-magicians.org/search?q=ERC-6150 | ## UX Impact Filesystem-like hierarchical NFTs — tokens have parent/child relationships like folders and files. Design implications: show folder tree navigation, display breadcrumb paths, enable create-under-parent flows, indicate root vs leaf tokens, show children count. Design decisions: max depth visualization, whether to support drag-drop reorganization, handling permission inheritance in hierarchy, folder vs file visual treatment. ## Summary Filesystem-like hierarchical NFTs — tokens have parent/child relationships like folders and files. ## For Designers - You can show folder icon for parent tokens and file icon for leaves in tree sidebar. - Your breadcrumbs can read Collection › Season › Episode › Item for orientation. - You can offer Create inside folder with parent pre-selected in mint flow. ## Applicability ### When to Use - Collection has natural hierarchy — courses, seasons, albums. - Users navigate hundreds of related tokens. - Parent-child minting is on-chain. ### When to Avoid - Flat 10k PFP drop with no structure. - Hierarchy depth breaks mobile layout without design. - No parent id in contract. ## Problems It Solves ### Flat grid unusable for structured collections Impact: high Old way: 1000 items one page New way: Folder tree navigation ### Users lost in deep collections Impact: medium Old way: No idea where item lives New way: Breadcrumb path on every detail ### Minting without structure Impact: medium Old way: All tokens sibling flat New way: Create under parent mint flow ## Anti-Patterns ### Flat grid for 500-item hierarchical collection Severity: high Unbrowseable Instead: Tree or folder drill-down ### Drag-drop reorg without confirm Severity: high Accidental structure changes Instead: Explicit Move with confirmation ### No breadcrumb on deep items Severity: medium Disorientation Instead: Always show path to root ## Design Decisions ### Max tree depth in sidebar? Recommendation: Indent max 4 levels then breadcrumb-only. Rationale: Mobile cannot fit deeper indents. ### Drag-drop reorganize? Recommendation: Avoid unless contract supports; use explicit Move to folder. Rationale: Accidental drags restructure valuable trees. ### Folder tokens tradable? Recommendation: If yes, warn Selling folder includes N children. Rationale: Bundle sale surprise otherwise. ## States to Design ### Viewing root collection Trigger: User at tree top. User need: See top-level folders. Design response: Grid or tree of root children only. ### Inside folder Trigger: Opened parent token. User need: See children and navigate up. Design response: Breadcrumb plus children grid. ### Deep leaf detail Trigger: Selected leaf at depth 4+. User need: Know location in hierarchy. Design response: Full breadcrumb; sidebar sync. ### Empty folder Trigger: Parent with zero children. User need: Understand empty not error. Design response: Empty folder illustration plus Mint here if allowed. ### Mobile depth limit Trigger: Tree too deep for screen. User need: Still navigate. Design response: Breadcrumb-only mode; sidebar as drill-down pages. ## Vocabulary - Use "Folder" instead of "Parent token node": Filesystem metaphor. - Use "Collection path" instead of "Parent id chain": Breadcrumb language. - Use "Create here" instead of "Mint with parentId": Creator action language. ## What to Prototype First ### Tree sidebar navigation Primary navigation for hierarchical collections. Covers: Expand folders, Select leaf, Deep path - Tree component - Icons folder/file - Selected highlight ### Breadcrumb header Deep items need path context. Covers: 3-level path, Root item - Clickable crumbs - Truncate middle on mobile ### Create under parent Creators mint into folder structure. Covers: Pick parent, Mint child - Parent selector - Child preview - Confirm mint ### Folder detail with children grid Opening folder shows contained items. Covers: Empty folder, Many children - Children count - Grid of leaves - Back to parent ## Mental Model ### Root token Top of tree — collection or volume. ### Folder token Parent with children — may not be tradable art itself. ### Leaf token Item with no children — the actual collectible. ### Path Root to current token — breadcrumbs encode this. ### Inherited permissions Rules on parent may affect children — disclose if applicable. ## Seen in the Wild - Google Drive: Folder tree mental model users already have. (https://drive.google.com/) - OpenSea: Collection hierarchy patterns for large sets. (https://opensea.io/) - Catalog: Music NFT organization informs hierarchical browsing. (https://catalog.works/) ## On Monad ### Tree loading Ethereum: Deep tree queries slow Monad: Fast reads enable eager tree prefetch Design implication: Prefetch one level of children on folder hover. ### Structured mints Ethereum: Many child mints costly Monad: Lower fees enable building deep trees on-chain Design implication: Bulk create-under-parent on Monad. ## UX Patterns ### NFT Folder Tree Sidebar tree with folder and leaf icons. Components: TreeSidebar, FolderIcon, Breadcrumb User flow: - Open collection - Expand folders - Select item - Breadcrumb updates Mockup registry key: `concept/nft-gallery` (React UI on the live standard page). ### Create Under Parent Mint child token into selected folder. Components: ParentPicker, MintForm, PathPreview User flow: - Select folder - Tap Create here - Mint child - Appears in folder Mockup registry key: `concept/permit-approval` (React UI on the live standard page). ## Related Standards - ERC-7401: Alternative nesting model owning child NFTs - ERC-721: Hierarchical extension ## Technical Notes ERC-6150 hierarchy uses parent pointers; cap sidebar depth and always show breadcrumbs.