About

Trello exports board data as a single JSON file containing lists, cards, labels, descriptions, comments, checklists, and vote counts. Reviewing this data in raw JSON is impractical - nested arrays, ID cross-references, and action logs make manual inspection error-prone. This tool parses the exported board.json structure, resolves all internal references (idList, idCard, idMember), and renders the board as a structured, human-readable HTML document optimized for printing. All processing occurs entirely in the browser. No data is transmitted to any server.

The converter handles boards with 1000+ cards, renders Markdown formatting in card descriptions, calculates checklist completion ratios, and groups comments chronologically under their parent cards. Toggle controls let you filter visible sections before printing. The print layout uses CSS page-break rules to prevent lists from splitting across pages. Note: this tool expects the standard Trello JSON export format. Custom or third-party export plugins may produce incompatible structures.

Formulas

The converter resolves cross-references within the Trello JSON using ID-based lookups. Each card references its parent list and associated members, labels, and checklists through identifier fields.

mapCardsToList: For each card ∈ cards[], group by card.idList → listMap[idList]

resolveComments: Filter actions[] where action.type = "commentCard", group by action.data.card.id

checklistProgress: ratio = completedItemstotalItems × 100%

sortCards: Sort by card.pos ascending (Trello's internal position value)

renderMarkdown: Parse desc for **bold**, *italic*, [link](url), - list items, `code`

Where card.idList is the foreign key linking a card to its parent list, action.data.card.id links a comment action to its parent card, and card.pos is a floating-point position value used by Trello for ordering cards within a list.

Reference Data

Trello JSON Field	Path	Type	Rendered As
Board Name	name	String	Page title & header
Board Description	desc	String	Subtitle block
Lists	lists[]	Array	Column sections
List Name	lists[].name	String	Section heading
List Closed	lists[].closed	Boolean	Hidden by default
Cards	cards[]	Array	Card blocks
Card Name	cards[].name	String	Card title
Card Description	cards[].desc	String (Markdown)	Rendered HTML
Card Labels	cards[].labels[]	Array	Colored badges
Card Closed	cards[].closed	Boolean	Archived indicator
Card Votes	cards[].badges.votes	Number	Vote count badge
Card Due Date	cards[].due	ISO 8601	Formatted date
Card Position	cards[].pos	Number	Sort order within list
Card Members	cards[].idMembers[]	Array of IDs	Member names
Checklists	checklists[]	Array	Checklist with progress
Checklist Items	checklists[].checkItems[]	Array	Checkbox items
Check Item State	checkItems[].state	complete / incomplete	Checked/unchecked
Comments	actions[] (type: commentCard)	Array	Comment threads
Comment Text	actions[].data.text	String	Comment body
Comment Author	actions[].memberCreator.fullName	String	Author name
Comment Date	actions[].date	ISO 8601	Formatted timestamp
Labels	labels[]	Array	Color-coded tags
Members	members[]	Array	Referenced by idMembers
Label Color	labels[].color	String	CSS background color

Frequently Asked Questions

Open your Trello board, click the board menu (three dots or 'Show menu'), select "More", then "Print and Export", and choose "Export as JSON". Your browser will download a .json file containing all board data including lists, cards, labels, checklists, comments, and member information. This is the file you paste or upload into this converter.

No. All JSON parsing, cross-reference resolution, and HTML rendering occur entirely within your browser using client-side JavaScript. The JSON content never leaves your machine. You can verify this by disconnecting from the internet before pasting your data - the tool will function identically.

By default, archived (closed) cards and archived lists are hidden. Use the "Show Archived Cards" and "Show Archived Lists" toggle controls to include them. Cards with closed = TRUE are treated as archived. Similarly, lists with closed = TRUE are hidden unless explicitly toggled.

The renderer uses document fragments for batch DOM insertion, avoiding costly reflows. Cards are grouped by list during a single pass through the cards[] array using a hash map keyed by idList. Boards with over 1000 cards render in under 2 seconds on modern hardware. A progress indicator appears during rendering for boards exceeding 500 cards.

Yes. The @media print stylesheet forces -webkit-print-color-adjust: exact and print-color-adjust: exact, ensuring label background colors appear on paper. Some older printers or browser settings may override this. Check your browser's print dialog for a "Background graphics" checkbox and ensure it is enabled.

The converter supports a subset of Markdown consistent with Trello's editor: bold (**text**), italic (*text*), inline code (`code`), links ([text](url)), unordered lists (- item), and line breaks. Full Markdown features like tables, images, or nested blockquotes are not rendered - they appear as plain text.

This tool expects the specific Trello JSON export schema, which includes top-level fields name, lists, cards, and actions. Exports from other project management tools (Jira, Asana, Notion) use different structures and will fail validation. The tool checks for required fields on parse and displays a specific error message identifying which expected fields are missing.