The Gantt Chart Maker That Explains Your Schedule
- Free
- No sign-up
- Works offline
Tasks, dependencies, milestones, and a critical path — then press Present and the plan reveals itself, step by step, with narration.
Present reveals your Gantt chart one step at a time, on its own.
Diagramium's Gantt chart maker is a free, browser-based editor with one unusual feature: press Present and the schedule explains itself, revealing tasks one at a time with optional AI voice narration. You get the full project-scheduling kit — tasks, dependencies, milestones, percent complete, a critical-path highlight, and a Today marker — with no account and no download.
Schedules can run on real calendar dates or on plain project days, and the time axis switches between Daily, Weekly, and Monthly views so a long project compresses to a single screen. Everything is local-first: your chart lives on your device and in the files you export, and the editor keeps working offline once loaded.
How to read a Gantt chart: bars, arrows, and diamonds
A Gantt chart plots every task as a horizontal bar on a shared time axis: the bar's left edge marks the start, its length is the duration, and its fill level shows percent complete. That one convention is why the format has survived a century of project management — the whole plan is readable at a glance, without a legend.
- Dependency arrows connect a task to the work that must finish before it can start. A chain of arrows is the skeleton of the schedule.
- Milestones are zero-duration markers — a launch, a sign-off, a contract date. They anchor the plan to commitments rather than effort.
- The critical path is the chain of dependent tasks that sets the project's finish date; slip any task on it and the end date slips with it. Diagramium highlights it, so the tasks with no slack stand out from the ones that can float.
Add the Today marker — a vertical line at the current date — and the chart answers the status question too: everything left of the line should be filled in.
Real dates, project days, and an axis that compresses
Diagramium's Gantt editor runs on real calendar dates or on plain project days — Day 1, Day 5, Day 30 — so you can sketch the shape of a plan before anyone commits to a start date, then anchor it later.
The time axis switches between Daily, Weekly, and Monthly scales, with the day count per column shown on the axis. That switch is what keeps long projects honest: a two-week sprint reads comfortably at Daily, while a year-long program collapses to one screen at Monthly without hiding a single dependency. You pick the zoom level that fits the audience, not the other way around.
Walk the plan, bar by bar
A Gantt chart puts Present mode to real work: press Present and the plan reveals itself stage by stage — each task appearing in turn, a spotlight on the current bar, optional AI voice narration, and subtitles with word-by-word highlighting. Per-step speaker notes let you attach a "why this matters" insight to each task, so the kickoff narrative lives inside the chart instead of a separate slide deck.
That turns the chart into the meeting itself. A release plan walked through milestone by milestone lands differently than a static screenshot pasted into slides — the release plan guide shows the pattern in detail. If you are building your first one, start with how to make a Gantt chart — tasks, dependencies, milestones and the critical path.
From empty chart to shared plan
Building a presentable Gantt chart in Diagramium takes eight steps, from empty editor to exported file.
- Open the Gantt editor in your browser — no account, no install.
- Add tasks with a start and a duration, and drag bars to adjust them. Choose real calendar dates or plain project days.
- Draw dependency arrows between tasks that block each other, and drop milestones on the commitment dates.
- Set percent complete on in-flight tasks and use the Today marker so status reads at a glance.
- Highlight the critical path so the zero-slack chain stands out from the tasks that can float.
- Pick the axis scale — Daily, Weekly, or Monthly — that fits the whole plan on one screen.
- Press Present to walk through the schedule task by task, or add narration and speaker notes first.
- Export a PNG or SVG for free. The animated exports — GIF, video, animated SVG — come with a free account exports, and you can also record the presentation live.
Gantt chart or timeline — which one?
A Gantt chart is for work that has duration and dependencies; a timeline is for events that happen at points in time. If your rows are tasks that block each other and you care about who is waiting on whom, you want a Gantt chart. If you are telling the story of what happened — a product's history, a project retrospective — the timeline editor is the better fit: events in order, with no scheduling machinery in the way.
Not sure yet? The template gallery has ready-made, editable examples of both, so you can open one, swap in your own tasks, and keep the structure. Any published gallery diagram can also be embedded on another website as a self-playing frame, so a walkthrough plays right on the page instead of sitting there as a stale screenshot.
Frequently asked questions
Is the Gantt chart maker free, and do I need an account?
The Gantt chart maker is free, and no account is needed to build a chart, present it, or export it as a PNG or SVG. A free account unlocks the animated export formats and syncs your gallery favorites — there is no paid tier.
What formats can I export a Gantt chart in?
A Gantt chart exports as PNG or SVG with no account. Animated GIF, video, and animated SVG exports unlock with a free account, and you can also record a live run of the presentation as it plays.
Does the Gantt chart maker work offline, and where are my charts stored?
The Gantt chart maker is local-first: charts live on your device and in the files you export, no feature uploads diagram content, and the editor keeps working offline once it has loaded. There are no ads, no third-party analytics, and no tracking.
Can I use real calendar dates in the Gantt chart?
A Gantt chart in Diagramium runs on real calendar dates or on plain project days, whichever fits the stage of planning. The time axis switches between Daily, Weekly, and Monthly scales, with the day count per column shown, so long schedules compress to one screen.
How does the critical-path highlight work?
The critical path is the chain of dependent tasks that determines the project's finish date — if any task on it slips, the end date slips with it. Diagramium highlights those tasks in the chart so the zero-slack chain stands out from the work that has room to move.
Can a Gantt chart show progress against today's date?
Yes — each task bar carries a percent-complete fill, and the Today marker draws a vertical line at the current date. Read the two together and the chart shows status at a glance: bars left of the line should be full, and any that are not are behind.
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