The trap with Visio is treating it as one tool when it is really two: a loose canvas for flowcharts, org charts, and brainstorming maps, and a precise instrument for scaled floor plans, network layouts, and technical drawings. No single open source program covers both halves well, so the honest first move is naming which half you actually live in before you shop. Open source here gives you desktop programs that store drawings in inspectable formats, export to PNG, SVG, and PDF for documents, run offline without a separate license per contributor, and read the standard CAD interchange files that keep technical work portable between tools for years rather than trapping it in one vendor's format.
LibreCAD is a 2D CAD program for creating and editing technical drawings. Based on the community edition of QCAD and built on the Qt framework, it runs as a desktop application on most operating systems, with a highly customizable interface translated into more than 30 languages.
DesktopNaotu is a localized desktop version of Baidu Mind Mapping. It lets you build and edit mind maps with no internet connection, so the tool stays usable in offline or local-only environments.
QCAD is a 2D CAD application for Windows, macOS, and Linux, built for creating and editing technical drawings. It reads and writes the DXF format natively, with optional DWG support available through a separate proprietary plugin.
Heimer is a desktop application for creating mind maps, diagrams, and note-taking layouts. It is written in Qt and targets Linux and Windows, with an easy-to-use interface for arranging nodes and labels.
VYM (View Your Mind) is a mind mapping application for visualizing thoughts in tree-like structures. The same maps also work for time management, self-organization, and sorting through new ideas and complex contexts.
Pick by whether your Visio work is drawn to scale or sketched as ideas.
Scaled technical drawing and floor plans: LibreCAD LibreCAD is a full 2D CAD program for drawings that have to be precise: floor plans, elevations, and network layouts built from lines, arcs, circles, and splines. It reads and writes DXF and DWG and exports to PDF and SVG, so drawings exchange with other CAD tools instead of getting stranded. A command-line mode batch-converts DXF files to PDF, PNG, or SVG for publishing large sets.
Scriptable CAD drawing: QCAD QCAD covers the same 2D technical drawing ground and adds automation: a complete ECMAScript and JavaScript scripting interface, plus a C++ plugin API, for repetitive or generated drawings. It reads and writes DXF natively, with DWG available through a separate plugin. Choose it over LibreCAD when scripting matters more than out-of-the-box DWG support.
Quick cross-platform mind maps: Heimer Heimer is a lightweight desktop tool for mind maps and node diagrams, with automatic layout, autosave, and full undo. It saves to a simple XML-based .ALZ format and exports to PNG or SVG for dropping into documents. It suits org charts and brainstorming maps, but runs on Windows and Linux only.
Offline idea mapping: DesktopNaotu DesktopNaotu is an offline desktop build of Baidu Mind Mapping that works with no network connection, editing local km files with automatic saving. It runs on Windows, macOS, and Linux with a multilingual interface, a practical choice when maps must stay on the machine and off any cloud service.
Visio's file format, .vsdx, is the first thing to let go of, because none of the open source options here is built to read it. That sounds worse than it is. What they replace is the work, not the container: LibreCAD and QCAD speak DXF and DWG, the interchange formats that keep scaled drawings moving between CAD tools, while Heimer, VYM, and DesktopNaotu keep node-and-branch maps in their own simple XML or km files. Decide up front whether your Visio library is really technical drawing or really idea structuring, because that split maps almost exactly onto these two groups of tools.
The clean matches are the technical ones. If your Visio work is floor plans, elevations, or network layouts drawn to scale, LibreCAD reads and writes DXF and DWG directly and QCAD adds a scripting interface for repetitive drawings, so precise geometry survives the move. Flowcharts, org charts, and mind maps are a looser fit: the mapping tools here produce trees and connected nodes rather than Visio's free-form connectors and stencils, so expect to rebuild diagrams by hand rather than import them. Custom stencils, shape data, and data-linked diagrams do not carry across at all.
Keep your old diagrams readable while you move. Export the drawings you still need as PDF or SVG so they stay legible regardless of which tool wins, then rebuild only the diagrams that are still living documents. LibreCAD can batch-convert DXF files to PDF, PNG, or SVG from the command line, which helps when you have a large archive to publish rather than edit.
Not directly. None of the tools here advertises Visio .vsdx import, so treat your existing drawings as archives rather than editable sources. Export the ones you still need from Visio as PDF or SVG so they stay readable, and rebuild active diagrams in the new tool. For scaled technical drawings, moving through DXF or DWG into LibreCAD or QCAD preserves far more than a flat screenshot would.
LibreCAD and QCAD are the closest fit, because both are true 2D CAD programs that draw to scale with lines, arcs, circles, and splines. LibreCAD reads and writes DXF and DWG plus PDF and SVG, so drawings exchange cleanly with other CAD tools. QCAD reads and writes DXF natively and adds DWG support through a separate plugin, which matters if your archive is DWG-heavy.
The mind-mapping tools cover this, with a caveat. Heimer, VYM, and DesktopNaotu build node-and-branch diagrams with automatic layout, which suits org charts, mind maps, and simple process trees. They do not reproduce Visio's free-form connectors, swimlanes, or stencil libraries, so complex flowcharts with arbitrary routing will need rebuilding rather than a like-for-like conversion.
Yes. Heimer, VYM, LibreCAD, QCAD, and DesktopNaotu are all desktop applications that run entirely offline, with no account or subscription per contributor. That removes the main friction of occasional Visio use, where a rarely opened drawing still needed a paid seat. Install the program on each machine that needs to edit, and the drawings live as local files you own.
Mostly, but check per tool. VYM, LibreCAD, QCAD, and DesktopNaotu all ship macOS, Windows, and Linux builds. Heimer is the exception: it targets Windows and Linux only, so Mac users on a mixed team should lean on one of the cross-platform options or plan to view Heimer maps through its exported PNG or SVG files instead.
Two of these are built for it. LibreCAD includes a command-line mode that converts DXF files to PDF, PNG, or SVG in bulk, which is useful for publishing a whole drawing set at once. QCAD exposes a full ECMAScript and JavaScript scripting interface plus a C++ plugin API, so repetitive or generated drawings can be produced programmatically rather than clicked out by hand.
All of these export to formats that embed cleanly. Heimer exports maps to PNG or SVG, while LibreCAD and QCAD produce PDF and SVG alongside their native CAD formats. SVG is the most future-proof choice for diagrams because it stays sharp at any size and remains editable, and PDF is the safest for long-term, read-only archives that any viewer can open.
