📈 Gantt Chart Builder
v2.12
Load an Excel (.xlsx or .xlsm) workbook,
Only table headers Title, Start Date, and End Date are required.
Download example Excel here

Import, create and edit Gantt charts. Save to Excel or standalone html file.
🔒 Runs entirely in your browser. Your file is never uploaded — all processing happens locally on your device. Download offline app below.
✨ Tip: Click Browse below to open an .xlsx file and save changes directly back to it!
(Drag and drop, or using .xlsm files, will result in downloading a new file on save)
Changes since
About Gantt Chart

Visualise your project planning as an interactive Gantt chart.

Managing Tasks
  • Edit: Click any task bar, or hover a bar and click the ✎ button that appears to its side. Hovering a task row in the left panel also reveals the same shortcuts.
  • Add: Use the global "Add Task" button in the toolbar, hover a Phase/Category row to reveal an inline "+" button, or press n while hovering a Phase or Category row.
  • Duplicate / Chain: Inside the Edit modal, use Duplicate Task to copy (comments are copied too), or Dependent Task to create a follow-on task pre-linked to the current one (comments are not copied). The main view scrolls to the new task after creation.
  • Delete: Click "Delete" inside the task's Edit modal.
  • Rename Phase / Category: Hover a Phase or Category row to reveal a ✏ pencil button, then click to rename (or press e / r). If the new name already exists you will be offered a merge or a numbered duplicate.
  • Unsaved edits: While an Edit modal is open, any field that differs from its saved value shows an amber label * and a coloured left border, so you always know what has changed before saving.
  • Save & Close: Pressing Save & Close in the Edit modal automatically flushes any pending unsaved comment before saving.
Comments
  • Hover a task bar (or a task row in the left panel) and click 💬 to open the Comments modal, or use the keyboard shortcut c while hovering.
  • Each comment is stored with the author name and date+time. The task tooltip shows the total comment count and a preview of the latest note.
  • Comments can be edited or deleted inline — hover any comment to reveal ✏ Edit and 🗑 Delete buttons.
  • Author names are remembered for the session and colour-coded consistently across all comments.
Edit & Comments Modal Views
  • Every task modal has a view bar at the top with three buttons: ✏ Edit, ▭▭ Both (side-by-side), and 💬 Comments. Switch between them freely — the current task is preserved.
  • While a modal is open, use keyboard shortcuts to switch views instantly: e Edit  |  b Both  |  c Comments.
  • Press Esc to close any modal. If the edit form has unsaved changes you will be prompted before the modal closes.
Navigation & Filters
  • Scrolling: Click and drag the chart to pan. Release mid-swipe for momentum scrolling. Click the glowing pills at the timeline edges to extend past or future range.
  • Views: Toggle between Week, Month, and Year timelines. Week mode aligns to Mondays. Press v to cycle through views, or t to jump back to today.
  • Filters: Use "All", "Active" (excludes On Hold), and "Overdue" to focus on specific tasks. Empty categories are automatically hidden. The Filter button opens a panel with toggleable chips to filter by Status, Priority, Comments, Dependency, and Overdue state — active filter values appear in a summary bar below the timeline header.
  • Compact Mode: Narrows the left panel and stacks filters vertically to maximise chart space. Hover any row for a full-detail tooltip.
  • Reload: Click the Date Pill in the top-left to reload from the source file without creating a new snapshot.
  • Dependency arrows: Hovering a task bar with a dependency highlights its incoming arrow in amber.
Appearance
  • Light / Dark mode: Click the ☽ / ☀ button in the bottom-right corner of the chart, or press m anywhere in the main view. The preference is remembered across sessions and the app will also auto-detect your system colour scheme on first visit.
  • Colour palette: Click the palette button (next to the dark-mode toggle) to cycle through the available themes. Light mode offers: High Contrast, Catppuccin, GitHub Light, Ayu, and Kanagawa. Dark mode offers: High Contrast, Catppuccin, Frappé, Monokai, Dracula, Ayu, and Kanagawa. Each mode remembers its own palette independently.
Keyboard Shortcuts
Context Key Action
Hovering a task bar or left-panel task row e Open Edit modal
Hovering a task bar or left-panel task row c Open Comments modal
Hovering a task bar or left-panel task row d Create a Dependent Task
Hovering a task bar or left-panel task row n Duplicate the task
Hovering Phase/Category row e / r Open Rename modal
Hovering Phase/Category row n Add a new task to that group
Main view (no modal open) s Save Excel
Main view (no modal open) i Toggle Info panel open / closed
Main view (no modal open) v Cycle view: Week → Month → Year → …
Main view (no modal open) t Jump to Today
Main view (no modal open) m Toggle Light / Dark mode
Any task modal open e / b / c Switch to Edit / Both / Comments view
Any modal open Esc Close modal (prompts if unsaved)
Saving & Snapshots
  • Save Excel creates a versioned snapshot: it writes the current tasks back to the Current Planning sheet and appends them as a new timestamped entry to the Log sheet, making it available in the Compare dropdown. On supported browsers (Chrome/Edge) with a file opened via "Browse", it overwrites the original file directly; otherwise it downloads an updated .xlsx.
  • Auto-Save appears in the toolbar on supported browsers (Chrome/Edge) when a .xlsx file is opened via "Browse". When enabled, it silently rewrites only the Current Planning sheet after each confirmed edit — so your work is safe even if the browser is closed unexpectedly. Auto-Save does not create a Log entry or add anything to the Compare dropdown; it is purely a safety net to preserve the latest task state between sessions.
  • On-open snapshot (automatic): Every time you open a file, the app compares the Current Planning sheet against the most recent Log entry. If they differ — for example because tasks were changed via Auto-Save since the last manual save, or the file was edited externally — a snapshot is silently appended to the Log, timestamped with the file’s last-modified date. No action required; this keeps your history complete automatically.
  • Use the Compare dropdown to overlay any snapshot as ghost tracks on the chart. Changed fields are highlighted in the tooltip; the Stats flyout summarises milestones, completions, overruns, and more.
  • Export Chart packages the current view into a standalone read-only HTML file for sharing — no Excel file required to open it.
Icon Legend
  •  Open Phase Milestone (red flag)
  •  Completed Phase Milestone (green flag)
  •  Done items count (category row)
  • ⚠️  Overdue items count (category row)
  •  Active items count (category row)
  • 💬  Open Comments modal (bar hover)
  •  Open Edit modal (bar hover)
  •  Rename Phase or Category (row hover)
  • [!]  Hidden task dependency (collapsed parent)
  •  Historical Snapshot (Ghost) item

Privacy: Runs entirely in your browser. Files are never uploaded — all processing happens locally.

Version: v2.12

The latest version can always be found on the Live App or at the GitHub Repository.

Created by Kerwin Olfers · Released under the MIT License.