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.
v1.6.1 RELEASED AUGUST 2026OFFLINE-FIRST NO NETWORK REQUIRED AFTER DOWNLOADDEPENDENCIES ZERODATA OWNERSHIP 100% LOCAL · YOUR DISK · YOUR FILEBROWSER CHROME · SAFARI · FIREFOX · EDGEFOUNDED UNITED KINGDOMv1.6.1 RELEASED AUGUST 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
v1.6.1
Aug 2026
Persistent "Free" badge in the header for unlicensed users - click it to see what Solo unlocks. Never shown once a license is active.
Undo (Ctrl/Cmd+Z, toolbar button, and right-click menu) for task edits, indent/outdent, delete, and other plan changes made during the current session
AI Prompt Helper now guides milestone creation when generating a plan
Esc key now closes the task edit panel
Grid View: double-click a task row to open the edit panel; Edit Task is also now available from the right-click menu in both Gantt and Grid views
Removed "Copy Task List", consolidated into "Copy Plan for AI", now available from both the AI menu and Share menu
Pasting a plan from AI now creates milestone tasks when explicitly marked as a milestone in the source text
Day-level zoom now shows day-of-week headers and gridlines
Task Ref now appears directly after Task Name in the edit panel, and its column heading and values are centred in both Gantt and Grid View
Grid View: adding a subtask no longer opens the edit panel, consistent with adding a task
v1.6.0
Aug 2026
New optional "Task Ref" field - a stable, user-defined way to refer to a task that doesn't shift when rows move, unlike the row number. Off by default, turn it on in Settings > Columns (separately for Gantt and Grid View); shows to the left of Task Name, editable in Grid View and the side panel, and always included in CSV export
Task Ref is now also always included in PDF and PNG export, regardless of whether the column is currently toggled visible on-screen
Added an optional Task Ref prefix in Settings (e.g. "PROJ-") - shows in front of every Task Ref value everywhere it appears (Grid View, Gantt View, edit panel, CSV/PDF/PNG export) without being part of the stored value itself, so it can be changed later without editing every task
Grid View (Solo) now supports drag-and-drop row reordering, matching the Gantt task list - drag a task up or down to reorder it, or into another task to re-parent it, including dragging whole groups of subtasks at once
Right-click a task name (Grid View or Gantt View) for a new menu: Indent, Outdent, Add subtask, Add Task, Duplicate Task, Highlight colour, and Delete, instead of only the colour picker
Duplicating a task copies it (and any subtasks) as a new independent copy, with dependencies re-pointed correctly and progress/actual dates reset
Fixed PDF and PNG export producing a broken, blank file when triggered from Grid View or the Late Tasks view - export now correctly captures the Gantt chart regardless of which view is currently open, then returns you to the view you were on
"Copy plan for AI" and "Review my plan" now also include the row number, Task Ref, Milestone, Status, Bucket, Actual Start/Finish and Effort for each task, not just name/assignee/dates/% complete
"Copy Task List" now includes a Task Ref column
Fixed Share Read Only not preserving your column visibility settings (Assignee, %, Status, dates, Milestone, Bucket, Notes, Depends On, Effort, Task Ref, etc.) or Task Ref prefix for the person you shared with - they now see the plan exactly as you had it configured, not the default columns
Fixed Share Read Only allowing task data to be edited directly in Grid View - Grid View is now correctly locked, matching Gantt View and Late Tasks view
Start and End date are no longer required to save a task - you can leave one or both blank, in the side panel and in Grid View, matching how new tasks already start out
Fixed several pages (template purchase downloads, template pages, About) not logging the free download at all when a user clicked "Download Free"
Marketing pages now always show the correct current version number and release date automatically, instead of relying on someone remembering to update it by hand
The app now checks for new versions periodically in the background, not just on page load, so a browser tab left open for days will still show an update notification without needing a refresh.
Fixed a crash where a task depending on another task that has no dates yet could break the Gantt chart, saving, or the working-days/holiday settings
Fixed a bug where a parent task could keep showing a stale date range on its bar after every one of its subtasks had its dates cleared
Fixed deleting a task not renumbering the remaining tasks or updating parent date ranges
Fixed adding a subtask to a collapsed task leaving the new subtask hidden until manually expanded
Fixed the right-clicked row losing its highlight as soon as the cursor moved onto the menu - it now stays highlighted for as long as the menu is open
v1.5.3
Jul 2026
Minor bug fixes.
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.
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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