Dia is a diagram editor for building flowcharts, UML models, entity-relationship diagrams, and network layouts from ready-made shape libraries. It is used when a drawing has to be precise, editable, and easy to export as vector artwork or an image.
Dia is a diagramming application that places shapes, lines, and text on a canvas and keeps every element editable afterwards. You pick a tool set from a sheet, such as flowchart, UML, entity relationship, network, or circuit shapes, drag objects onto the page, and connect them by dragging lines between their connection points, so arrows follow when a box is moved. Layers hold background grids, annotations, and alternate views in one file. Diagrams are stored in an XML-based format, which means they can be diffed and versioned like source code, and the same file can be exported to vector or bitmap formats for documentation, slides, or printing across several pages.
Dia suits work where a diagram has to survive review. A database schema, deployment plan, or approval workflow changes many times, and because objects stay connected, editing one node does not leave a trail of stranded arrows. Shape sheets can be loaded on demand, so the toolbox stays short for the drawing at hand rather than showing hundreds of unused symbols. New shapes are defined in simple XML that uses a subset of SVG, which means a team can add house symbols without writing program code. The file format is plain enough to sit in a repository beside specifications, and diagrams often end up as attachments to schedules and documents, such as a network layout referenced in a ProjectLibre plan.
Dia's value is that it stays out of the way of the drawing. There is no account to create, no template gallery, and no document model to learn: the canvas, the toolbox, and the sheet selector are the whole interface, so a first diagram takes minutes rather than an afternoon. Precision is available when it matters, with grids, snapping, and object alignment, and the connection points mean a diagram keeps its logic when the layout is rearranged. Because diagram files are XML, they can be stored, compared, and reviewed alongside code or specifications instead of living in a binary that only one program can read. Export options cover the usual handoff points: SVG and EPS for print and vector editing, PNG for slides and wikis, and interchange formats for tools that expect them. Command-line export lets a build step or script regenerate images from a folder of diagrams, which keeps published documentation from drifting away from the source drawing. For engineers, teachers, and analysts who need a clear schematic rather than a design suite, that focus is the point.
Key capabilities and highlights.
Toolboxes are organised into sheets for flowcharts, UML, entity relationship models, network layouts, circuits, and other diagram families, and sheets load on demand. That keeps the palette short for the drawing you are making while still offering more than a thousand ready-made objects.
Most objects carry connection points, so a line snapped to a box stays attached when that box is moved, resized, or reshaped. Complex relationships survive editing rounds without manual repair, which matters on diagrams that are revised for months.
Drawings can be split across layers, keeping grids, annotations, and variant layouts in the same file. Show or hide layers to present one version to an audience and another to the engineers, and limit which layers are included when exporting.
New symbols are defined in small XML files that describe the outline with a subset of SVG, so organisations can add their own icons, stencils, or notation to the toolbox. Adding a house shape does not require writing or compiling program code.
Finished diagrams leave as SVG, EPS, PNG, or other formats chosen for the destination, so the same drawing can go to a print workflow, a wiki page, or a slide deck. Vector output scales without blurring, while bitmap output keeps file sizes manageable.
Dia can be scripted with Python, and the command-line interface converts a diagram file to a chosen format without opening the window. That makes it practical to regenerate documentation images automatically whenever the source drawing changes, instead of exporting each file by hand.
Files are saved in an XML format, compressed by default to keep them small, which means a diagram can be diffed in version control and reviewed like any other text document. Nothing is locked behind a binary blob only one program can interpret.
Oversized diagrams can be printed across several sheets and reassembled into one wall chart, which is common for network maps, process landscapes, and teaching material. Page breaks and margins are set inside the same print flow used for ordinary output.
Browse historical releases and previous builds.
No old versions have been added yet.
Common questions about Dia.
It is used to draw structured diagrams such as flowcharts, UML models, entity relationship diagrams, network maps, and circuit schematics. Because the output stays editable, it suits documentation that gets revised rather than one-off pictures.
It covers the same ground for most everyday diagramming: shape libraries, connectors that stay attached, layers, and export to vector formats. Teams that only need clear schematics usually find it sufficient, while Visio-specific templates and integrations are not replicated.
Yes. Shapes are defined in small XML files that draw the outline with a subset of SVG, and adding one does not require compiling code. Finished diagrams can also be exported as shape files so the same symbols are reused in later work.
Common choices include SVG, EPS, PNG, DXF, and CGM, along with formats used by older drawing and publishing tools. Vector output is best for printing and further editing, while bitmap output is convenient for slides, wikis, and chat.
Most shapes have connection points, and lines attached to those points follow the shape when it moves or resizes. Combined with grid snapping and alignment controls, that keeps a diagram readable after several rounds of edits instead of leaving stray arrows behind.
Yes. Dia can be scripted with Python, and the command-line export option converts a saved diagram to a chosen format without opening the editor, so images embedded in documentation can be refreshed by a script or a build step.
Dia is a diagram editor for building flowcharts, UML models, entity-relationship diagrams, and network layouts from ready-made shape libraries. It is used when a drawing has to be precise, editable, and easy to export as vector artwork or an image.
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