READMEGantto is a full Gantt chart editor in one HTML file. Paste your AI-generated plan, drag bars, set dependencies - then save it as a file that's yours forever. No cloud, no account, no renewal.
v1.5.2 RELEASED JULY 2026OFFLINE-FIRST NO NETWORK REQUIRED AFTER DOWNLOADDEPENDENCIES ZERODATA OWNERSHIP 100% LOCAL · YOUR DISK · YOUR FILEBROWSER CHROME · SAFARI · FIREFOX · EDGEFOUNDED UNITED KINGDOMv1.5.2 RELEASED JULY 2026OFFLINE-FIRST NO NETWORK REQUIRED AFTER DOWNLOADDEPENDENCIES ZERODATA OWNERSHIP 100% LOCAL · YOUR DISK · YOUR FILEBROWSER CHROME · SAFARI · FIREFOX · EDGEFOUNDED UNITED KINGDOM
Everything you need. Nothing you don't.
A full Gantt chart editor in a single HTML file - no build step, no framework, no update nag.
01.A
Gantt chart, properly drawn.
Colour-coded bars, today-line, weekend shading, smooth zoom from daily to monthly view. Drag any bar to reschedule. Dependencies follow automatically.
01.B
Dependencies, four flavours.
Finish-to-Start, Start-to-Start, Finish-to-Finish and Start-to-Finish - with optional lag days. Violated constraints highlight in red until you fix them.
01.C
Subtasks & hierarchy.
Group work into phases with a collapsible WBS outline. Indent, outdent, and reorder rows by drag. Children inherit their parent's colour, unless overridden.
01.D
Filter by assignee.
Show only one team member's tasks. Discover, gently, who is overloaded this sprint. Then have the awkward conversation, off-line.
01.E
Plans you actually own.
Save and load as plain .json files. Import MS Project XML, Microsoft Planner, or open .mpp files directly - free, in your browser, no upload. Auto-saves between sessions.
plan.json 14 KB
01.F
Buckets & custom colours.
Group tasks by bucket - Dev, Design, QA - and pick any colour you like. Subtasks inherit.
Need to open a .mpp file without MS Project? Gantto opens it free in your browser.
Up and running, 30 seconds flat.
No sign-up flow. No "verify your email." No onboarding tour. The first thing you see is your plan.
T + 00s
Download the file.
Click Download Free. You get one file - gantto.html. No installer, no update channel, no auto-launch service.
T + 06s
Open it in your browser.
Double-click. It opens in Chrome, Safari, Firefox, Edge - any modern browser. No server. No internet connection required after this point.
T + 30s
Start planning.
Add tasks. Drag bars. Set dependencies. Save the plan as a .json file when you're happy. Commit it to git, mail it, drop it in Drive - your call.
One file. Two tiers.
Free forever, or pay once for Solo. No subscriptions, no renewal - that's the whole point.
TIER · FREE
£0/ forever
Everything you actually need to plan a project, right now.
Full Gantt chart editor
Task hierarchy & dependencies
Milestones & sprint bands
Assignee filtering & zoom levels
Save & load JSON plans
Share plans
AI context export
AI Prompt Helper & Paste from AI
Status tracking - Not Started, In Progress, Blocked and more
Open MPP files - view any .mpp file free in your browser
Don't start from a blank plan. Browse 8 ready-made templates - Wedding Planning, Product Launch, Software Sprint and more. Each one opens instantly in Gantto.
Yes. Once gantto.html is on your disk you can pull the network cable, fly to Tokyo, retreat to a cabin in Vermont - Gantto keeps planning. The only thing that needs internet is downloading it.
Q · 02
How does the Solo licence work?
£9.99, once. You get a licence key to enter directly in the app. The reminder popup disappears permanently. Use it in any browser you own, forever - no internet check, validated entirely offline.
Q · 03
What browsers are supported?
Chrome, Safari, Firefox, Edge - anything shipped in the last three years. Brave, Arc, Vivaldi: also fine. Chrome and Edge have the best experience, supporting the native file-save dialog when exporting plans.
Q · 04
Does Gantto work on mobile?
Gantto is designed for desktop browsers. On iPhone and iPad, Safari can't open local HTML files - download and open Gantto on a Mac or PC for the best experience. We're exploring mobile support for a future version.
Q · 05
Can I share the file with my team?
The app file is just HTML - share it freely. For plans, save the .json and send it however you send files. Collaboration features are on the roadmap. For now, save the .json and send it - it works surprisingly well.
Q · 06
Can I import an existing MS Project file?
Yes. Gantto opens .mpp files free in your browser - no MS Project needed. Solo users can also edit and save imported plans.
Q · 07
What happens to my data if I upgrade browsers?
Nothing, as long as you saved your plan as a .json file. The browser is just the viewer. The file is the truth.
Changelog
Recently shipped
v1.5.2
Jul 2026
Grid View (Solo) - a full-width, spreadsheet-style view of your plan alongside the Gantt chart. Edit task names, dates, assignees, status, dependencies and more directly in the grid. Resizable columns, right-click a task name to add a highlight colour.
Colour Themes (Free) - switch your plan's bar colours between Default, Muted, Pastel and Grey palettes from Settings. Applies across the whole plan, no per-task setup needed.
Fixed MPP import: task hierarchy, dependencies, dates and resource assignments are now correctly preserved instead of being dropped or flattened (MPP14 files).
Also in this release: circular dependency protection, and a range of Grid View polish fixes.
v1.5.1
Jul 2026
Minor bug fixes.
v1.5.0
Jul 2026
Baselines (Solo) - snapshot your plan at any point in time and compare it against the live schedule. Ghost bars appear below each task bar showing where dates were when the snapshot was taken. Up to 5 named baselines per plan, stored in the plan JSON file.
Plan History (Solo) - Gantto now keeps a rolling record of every save. Open File > Plan History to browse previous versions by date and restore any of them with one click. History travels inside the JSON file. Configure depth (10, 25, or 50) in Settings > Saving & Backup.
Non-working dates - add specific dates (public holidays, company days off) to exclude from scheduling in Settings > Plan. Tasks shift to the next valid working day.
Column resize - drag the right edge of any column header to resize it; double-click to reset to default width.
Column visibility - show or hide individual task list columns from Settings > Columns.
Parent task bars now use a bracket style, making them visually distinct from leaf task bars.
Smart Gantt scroll - the chart opens at a useful default position and remembers scroll position per plan.
Startup modal for returning users - prompts to continue last plan, open a file, or start fresh.
Sample plan now accessible at any time from the Help (?) menu.
Share Read Only: banner links to gantto.app, theme toggle for viewers, baselines included in exports.
Save Plan As added to the File menu. Plan title now directly editable in the title bar.
New tasks persist immediately on creation - closing the edit panel no longer discards the task.
Fixed: dependencies not saving on tasks created via Paste & Parse.
Fixed: task hierarchy reliability across all structural operations.
Fixed: dependency arrow positions and routing for all task types.
v1.4.0
Jun 2026
Bar Label - add a short label next to any task's Gantt bar, with its own auto-contrast or manual colour control
New /about page with Gantto's project history
Hover tooltips added throughout the Share and AI menus
Post-export toast after Share Read Only export explaining how to use the file
Saving a task in the edit panel now keeps it focused afterwards, so Add Task inserts directly below it
Share Plan (URL-based) replaced with Share Read Only (Solo) - export a fully navigable, locked HTML version of your plan, viewable anywhere with no account or install
Read Only exports can now be protected with an optional passcode
Toolbar and menus restructured: File menu, More menu (Export, Import, License, Appearance), and an expanded View dropdown
Version chip replaces the old update notification banner, always visible next to the logo
Fixed: Gantt hover info now only triggers directly over a task bar or milestone, and no longer appears while dragging or resizing
Removed the resize handle from parent task bars - a parent's length is driven entirely by its children
Fixed: the "What's New" button in the version chip now opens the in-app changelog instead of linking out to the website
Dependency scheduling toggle in Settings - choose between auto-sync (dependent tasks shift automatically) or highlight only (tasks in jeopardy shown in red, dates unchanged)
Updated walkthrough with new Settings step and revised Save & Load copy
What's New in v1.4.0 tour - highlights Share Read Only, dependency scheduling toggle, actual dates, milestone labels, and Settings
Fixed: auto-sync now correctly cascades when a parent task's dates change as a result of editing one of its children, not just when the parent itself is edited or dragged directly
v1.3.7
Jun 2026
Removed small screen warning notice
Moved help (?) and feedback (💬) icons into the top bar, to the left of the license key icon
Replaced Add Task button with a circular + button in lime green; same button also appears at the bottom of the task list
Removed accidental task creation when clicking empty space below the last task
Fixed: milestone text now uses the same colour logic as task bar text, fixing white text rendering regardless of colour selection
v1.3.6
Jun 2026
Dependencies now use stable task IDs instead of row positions - fixes arrows breaking when tasks are inserted or moved above a referenced task
Existing saved plans migrate to the new format automatically on first load, no action needed
Fixed: Move Up and Move Down buttons no longer break dependency references
Fixed: "Update Available" no longer appears when the live site's version is older than yours
Feedback button moved to the bottom-left, next to the ? button
v1.3.5
Jun 2026
Copy Task List - new Share menu option copies the task grid as a markdown table to the clipboard
Respects active filters and preserves subtask hierarchy with indentation
Fixed: tutorial no longer shows the upgrade prompt when a license is already active
Fixed: export lock icons now clear instantly on license activation, no refresh needed
Milestone name labels always visible on Gantt chart
Bar label text auto-contrast based on bar background luminance
Optional per-task bar label colour override in Edit panel
Gantto.app is an independent project built in the UK in 2026. Not affiliated with the original 2010 Gantto (YC S10, acquired 2013).
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