DWG viewer online, free and without AutoCAD

Three steps#

Drop the DWG on the box above, or open cicada and press DWG in its toolbar. You can also drop the file anywhere on cicada's drawing sheet.
cicada reads the file in your browser tab and zooms so the whole drawing fits.
A message says which DWG version it was and how many of its objects were read. The command line under the sheet lists the kinds that were left out.

The file is read by the page itself. It is not uploaded, and there is no account to make.

Which DWG files open#

Every DWG starts with six letters that say which AutoCAD format wrote it. cicada reads the first six bytes and decides from them.

Code	Format	In cicada
AC1032	AutoCAD 2018 and later	Opens. Checked against a drawing AutoCAD saved in it.
AC1027	AutoCAD 2013 to 2017	Opens. Checked against a drawing AutoCAD saved in it.
AC1024	AutoCAD 2010 to 2012	Opens. Checked against a drawing AutoCAD saved in it.
AC1021	AutoCAD 2007 to 2009	Opens. Checked against a drawing AutoCAD saved in it.
AC1018	AutoCAD 2004 to 2006	Opens. Checked against a drawing AutoCAD saved in it.
AC1015	AutoCAD 2000 to 2002	Opens. Checked against a drawing AutoCAD saved in it.
AC1014	AutoCAD R14	Opens. Checked against a drawing AutoCAD saved in it.
AC1012	AutoCAD R13	Opens. Checked only on a file the ODA File Converter wrote.
AC1009	AutoCAD R11 and R12	Opens. Checked against two drawings AutoCAD R11 saved and a file the ODA File Converter wrote.
AC1006	AutoCAD R10	Opens. Checked against a drawing AutoCAD saved in it.
AC1004	AutoCAD R9	Opens. Checked against a drawing AutoCAD saved in it.
AC1003	AutoCAD 2.6	Opens. Checked against two drawings AutoCAD saved in it.
AC1002, AC1001	AutoCAD 2.5 and 2.2	Opens with the rules of its neighbours. No sample file checks it.
AC2.10	AutoCAD 2.1	Opens. Checked against a drawing AutoCAD saved in it.
AC1.50, AC1.40	AutoCAD 2.0 and 1.4	Refused, with a message that names the code.

R13 to R2018 each store objects a little differently, so cicada reads each one with its own rules. The AutoCAD drawing holds 345 objects in every format from R14 to 2018. cicada reads 304 of them, and each one matches the DXF that AutoCAD saved from the same drawing. R13 and R14 keep names only in capitals; a newer AutoCAD stores the full name beside it, and cicada shows that full name unless the name was changed in R14. Files before R13 have no section map and no object map: cicada walks their tables and entity lists record by record, and on every sample it reads the same objects at the same coordinates as the DXF saved beside it. From these old files, shapes and points are read but not drawn. The arrays of AutoCAD 2.x are drawn in all their rows and columns.

A damaged DWG, for example one cut off during a download, still opens with every object that can be read. The message then turns red and counts the places where reading failed. Only a file with no readable object left is refused, and the message says why.

A drawing from AutoCAD 2.0 or older is refused, because no sample file shows how those releases store a drawing. Save it again in a newer release, or as DXF, in the program that made it. cicada opens DXF of every version, see the DXF viewer.

What you see, and what is left out#

cicada turns the drawing into shapes you can select, move and edit. These come through:

lines, arcs and circles
polylines, including their curved segments, the older 2D polylines and lightweight polylines
ellipses and splines, drawn as the curve they are
triangles and quadrilaterals (solids and traces), filled as AutoCAD fills them, dimension arrowheads too, or as outlines when the drawing turns FILLMODE off
hatches, as their boundary outline
single-line text and multi-line text, wrapped at the width of its box, with symbols such as ° and ± and stacked fractions
block attributes, showing the value AutoCAD shows, multi-line attributes included
dimensions, through the block AutoCAD caches with them
blocks, placed with their position, rotation and scale, nested up to eight deep
layers, with their colours, true colours included, and whether they are off, frozen or locked

These are not drawn yet: points, leaders and multileaders, tables, multilines, construction lines and rays, tolerances, shapes, wipeouts, images and PDF underlays, 3D solids, regions and meshes, viewports, and objects that come from AutoCAD add-ons. After opening, cicada lists what it left out by type, so you know what you are not seeing. A hatch shows its outline, not its pattern; a dimension shows the geometry AutoCAD stored with it, not a freshly measured one.

More things to know:

An object coloured on its own, not by its layer, shows in its layer's colour.
Capitals stand as tall as the text height in the drawing. Text in Arial, Consolas or Courier New is as wide as in AutoCAD, so wrapped lines break at the same words, and it is drawn in its own font where your device has it. Every other font, SHX stroke fonts such as txt.shx too, is drawn with Arial's letters and widths, so such text can come out wider or narrower than in AutoCAD.
A block reference clipped with XCLIP shows only what lies inside its clip, an inverted clip only what lies outside. Text that crosses the clip edge is shown whole.
Line weights show the way AutoCAD shows them in model space: only when the drawing turns its line weight display (LWDISPLAY) on. A line of 0.25 mm or less is drawn at the base width, a heavier one wider in proportion. R14 and older files store no line weights.
A block is placed by its base point. Every block in the test drawings is based at 0,0, so other base points are read but not yet checked against a real file.
Model space and paper space are drawn on the same sheet, so a title block from a layout can sit next to the drawing.

Save it as DXF or SVG#

Press Export and choose DXF or SVG. The file you get holds what cicada shows: the kinds of objects listed above, on their layers, with their line weights. The DXF is written in the newest DXF release, R2018 (AC1032), which every current CAD program reads. SVG opens in a browser, Inkscape or Illustrator. cicada does not write DWG. DWG to DXF lists what the DXF keeps and what changes on the way.

Measure and edit#

The drawing is not a picture. You can snap to end points, middles, centres and intersections, measure a distance or an area, trim and offset lines, add dimensions and move whole blocks.

The command line works like AutoCAD's: type L for a line, then points such as 100,50 or @40,0. The other short commands follow AutoCAD too, like O for offset, TR for trim and F for fillet. Ctrl K lists every command.

Questions#

Is it really free?#

Yes. There is no trial, no account and no paid version. The page runs in your browser and costs us almost nothing to serve.

Is my drawing uploaded?#

No. The DWG is read by JavaScript in the page you have open. Nothing about the file is sent anywhere. cicada keeps the drawing in your browser's storage so that it survives a reload; the privacy page says what is kept there.

Can I open a DWG on a phone or a Mac?#

Yes, in any current browser: Chrome, Edge, Firefox or Safari. On a phone the screen is small for drawing, but viewing and measuring work.

Why are my dimensions missing?#

They are not, in a file that carries them. cicada draws a dimension from the geometry AutoCAD caches next to it, so a linear, aligned, ordinate, radius or diameter dimension appears as the lines, arrowheads and text the drawing stored. If your file has none of them, cicada says how many objects it left out and by type.

Can I save back to DWG?#

No. cicada saves DXF and SVG. Most CAD programs, AutoCAD included, open DXF.