A GanttProject alternative with scenarios, AI and a modern interface
GanttProject is a free, open-source desktop Gantt tool with a loyal following and a dated interface. shadow-planner is a GanttProject alternative that's also free and open source, but adds scenarios, resource utilisation and an AI assistant on a modern stack.
GanttProject has been the go-to free desktop Gantt tool for a long time, and it deserves credit for it: no cost, open source, resource charts, critical-path-adjacent scheduling, and it runs anywhere Java does. If you just need a Gantt chart with dependencies and don't want to pay or account-create anything, it still does the job. What it hasn't kept up with is everything around the chart — the interface looks and feels like the Java desktop era it comes from, there's no concept of scenarios or what-if planning, and there's no AI assistance for building or steering the plan.
shadow-planner is built on the same principle — free, open source, runs locally, no account needed — but on a modern web-based desktop stack (Python/FastAPI, SQLite, a browser-rendered UI) with the things GanttProject doesn't have: isolated scenarios and snapshots, resource utilisation with cost roll-ups, a portfolio view, and an AI assistant that can draft or steer the plan. This isn't a knock on GanttProject; it's a genuinely different generation of tool aimed at the same "I don't want a SaaS subscription" audience.
Side by side
| shadow-planner | GanttProject | |
|---|---|---|
| Primary job | Planning and controlling: timelines, capacity, scenarios | Free desktop Gantt chart editor |
| Pricing | Free tier (1 scenario, 3 projects, 3 employees); €4,99 one-time for unlimited; open source, unlimited from source | Free, open source, no limits |
| Runs on | Windows, macOS, Linux; Python/FastAPI under the hood, browser-rendered UI | Windows, macOS, Linux; Java desktop UI |
| Interface | Modern, dark mode included | Classic Java Swing UI, functional but dated |
| Gantt / timeline | Drag-to-reschedule, finish-to-start dependencies, cascade preview before writing, day/month zoom | Drag-to-reschedule, dependencies, basic critical-path view |
| Resource utilisation | Weekly capacity vs. allocation, over-capacity highlighting, daily-rate cost roll-ups | Resource load charts |
| What-if scenarios | Isolated scenarios, snapshots, templates | Not a concept; save separate files manually |
| AI | Chat assistant over your data + planning agent; local (Ollama) or cloud model | None |
| Portfolio view | RAG status, cost and person-days across projects | Not a concept |
| Data storage | Local SQLite file | Local XML/GAN file |
Who should switch
- People who like GanttProject's price but not its era. Same free, local, no-account philosophy, with a current interface and features GanttProject never grew: scenarios, capacity planning, portfolio roll-ups.
- Anyone who wants to try before deciding on scale. The free tier is a full project (1 scenario, 3 projects, 3 employees) with every feature unlocked, not a stripped demo; €4,99 once removes the limits if you outgrow them.
- People curious about AI-assisted planning who don't want to give up local-first, no-telemetry principles — shadow-planner's default AI provider is a local Ollama model, so nothing has to leave the machine.
- Open-source users who want to inspect or extend the tool. shadow-planner's source is on GitHub too, and running from source is unlimited, same as GanttProject.
Who should stay
- You want the absolute minimum footprint — a lightweight Java app with no server process — and don't need scenarios, resourcing, or AI.
- You're already deep in GanttProject files and workflows and the switching cost isn't worth it for features you won't use.
- You need GanttProject's specific critical-path or PERT chart views, which shadow-planner doesn't replicate in the same form.
Both tools are free and respect your data; the difference is what's built around the chart. If capacity planning, what-if scenarios or an AI assistant would actually change how you plan, it's worth a look. See the AI Gantt chart or offline project planner pages for more on what's included.
Install shadow-planner for free, or grab the source from GitHub.