DWG File Viewer - Version Support and What Renders

A DWG file states its own format version in its first six bytes, and that code — not the year on the title block — decides whether a given reader can decode it. This page is the technical reference for DWG support here: the AC1014 to AC1032 table, how to check a file's version yourself, which entity types actually draw, and why DWG is harder to read than DXF.

The viewer runs entirely in your browser: the file is read from disk with FileReader and parsed in the tab by a LibreDWG WebAssembly build. Nothing is uploaded, there is no account, and there is no cap on how many drawings you open.

Open a DWG File

How to Tell Which DWG Version a File Is

Every DWG starts with a six-character ASCII version code, sitting at the very beginning of the file ahead of the binary payload. You can read it without CAD software of any kind. Three ways to get at it:

A plain-text editor. Open the .dwg in Notepad, TextEdit or VS Code. The rest of the first line is binary noise, but the first six characters are legible: AC1032, AC1027, AC1014. Close without saving — a text editor must never write back over a DWG.
A hex viewer. Cleaner, because nothing can be altered by accident. The code occupies offset 0x00 to 0x05: xxd drawing.dwg | head -1 on macOS or Linux, Format-Hex drawing.dwg in PowerShell on Windows.
This viewer. Load the drawing and the format version is reported for you, alongside the layer list and entity counts.

Match the code against the table below to get the AutoCAD release. Worth knowing when a client asks you to save down and you need to establish what you actually hold, or when a downstream tool rejects a file and you want to confirm the cause is the format version rather than damage.

Why the code matters more than the file date

The format is chosen at save time, not by the calendar. AutoCAD deliberately offers earlier DWG formats in its save dialogue, and plenty of practices standardise on one format for exchange with consultants, fabricators or a plant archive. So a drawing edited last week can legitimately report AC1027, and a file created in 2004 can report AC1018 forever. If you need to know what a file really is, read the header code, not the timestamp.

DWG Version Table: AC1014 to AC1032

Seven format codes cover roughly thirty years of AutoCAD output, and all seven decode here. Autodesk does not issue a new DWG format every year: one format is introduced and then reused across several annual releases, which is why the release column groups years together.

Header code	AutoCAD release	Years in use	Opens in this viewer
AC1014	AutoCAD R14	1997–1999	Yes
AC1015	AutoCAD 2000, 2000i, 2002	1999–2002	Yes
AC1018	AutoCAD 2004, 2005, 2006	2003–2006	Yes
AC1021	AutoCAD 2007, 2008, 2009	2006–2009	Yes
AC1024	AutoCAD 2010, 2011, 2012	2009–2012	Yes
AC1027	AutoCAD 2013 to 2017	2012–2017	Yes
AC1032	AutoCAD 2018 to 2026	2017–present	Yes

A file from AutoCAD 2026 reports AC1032; an archived 1998 drawing reports AC1014. Both open the same way, with no conversion step and no save-down request to the author. Civil 3D, Plant 3D and Advance Steel write these same codes, so their files load too, subject to the proxy-object limitation below.

Codes older than AC1014 sit outside the supported range: AC1012 from R13, AC1009 from R11 and R12, and the earlier 1980s codes. They are uncommon now; if you have one, an ASCII DXF export from any application that still reads it opens through the DXF viewer here.

What Renders and What Does Not

Version support and entity support are separate questions. A file can decode perfectly and still look incomplete, because a DWG can hold object types no third-party reader reproduces. The honest split:

Entity types that draw

Lines and polylines. LINE, LWPOLYLINE and POLYLINE, open or closed — the bulk of most 2D plans, sections and schematics.
Arcs, circles and ellipses. Curved primitives render as geometry, not as approximated straight runs.
Splines. Free curves are tessellated for display, so alignments and profile curves land in the right place.
Text. TEXT entities render and are indexed by the search tool, which is how a room name, part number or grid callout is found in a crowded sheet.
Blocks and inserts. INSERT references expand against their block definitions and draw their nested geometry: door and window symbols, fixtures, fasteners, standard details, title-block content.
Solids and 3D geometry. 3D content renders in solid, wireframe or x-ray mode, cuts with a clipping plane on X, Y or Z, and views from top, front or right presets in orthographic or perspective projection.
Layer structure. Each layer arrives with a colour swatch and an entity count and can be switched off on its own; killing hatch and annotation layers is the fastest way to read dense geometry.

What does not render

External references are not resolved. Only the host drawing is shown, so a sheet whose base plan arrives by xref opens looking sparse. Ask the author for a bound copy.
Proxy and custom objects do not render. Civil 3D corridors and surfaces, Advance Steel connections and similar objects are stored as custom entities only the authoring application fully understands.
Custom SHX fonts are substituted. Text appears in a standard face, so glyph shapes and text extents can differ from the plotted sheet.
Complex hatch patterns show as boundary outlines only. The region is delineated correctly; the pattern fill inside it is not reproduced.
DIMENSION entities in DWG files may not render. A known parser limitation. Where dimension text is the point of the review, an ASCII DXF export of the same drawing is the reliable route.
Nothing can be edited or written back. Geometry cannot be moved, layers cannot be re-assigned and no DWG is ever saved out. Markup lives on a screen overlay and survives only through an export.

Two things to know before you trust the output

Measurement does not snap. There is no endpoint, midpoint or centre snapping, and points project onto the ground plane, so distance and area are a sanity check rather than a certified value. PNG and PDF export are raster snapshots of the viewport, the PDF A4 landscape: text is not selectable and lines soften when the recipient zooms in. Both are review aids, not a plotted sheet.

When a drawing opens looking wrong, check the layer panel first in case content is switched off, then consider how much of the sheet is xref rather than host geometry, then ask for an ASCII DXF export. DXF takes a different parser here and often carries what the DWG path misses.

Why DWG Is Harder to Read Than DXF

DWG is a closed binary format. There is no full public specification, and its internal layout is version-specific: object encoding, compression and the class map differ between format generations, so AC1015 and AC1032 are not the same structure with more fields bolted on. Supporting DWG means maintaining a decode path per generation, which is why any non-Autodesk tool states its DWG support version by version rather than as a single yes.

DXF is the opposite by design: a documented interchange format, and in ASCII form a plain-text file of group codes and values you can inspect in a text editor. That is why this site runs two parsers, a LibreDWG WebAssembly build for DWG and an in-house parser for ASCII DXF.

Hence the fallback above. When a DWG feature does not survive the trip, dimensions being the usual case, the same drawing exported to ASCII DXF often renders, because it takes the simpler documented route. The full side-by-side is on DWG vs DXF, and what is a DWG file covers the format's background.

Try It With a Sample Drawing

These load straight into the viewer and behave exactly as your own files do. The 2D samples are DXF and exercise the same renderer, layer panel, measurement and export path a DWG uses.

Apartment floor plan Mechanical bracket Electrical schematic Site plan Steel beam detail A3 title block 18-tooth spur gear (3D) L-bracket (3D) All sample files

For your own drawing, drag the .dwg onto the viewer or use the file picker; the step-by-step walkthrough, including on a phone or tablet, is on how to open a DWG file.

Frequently Asked Questions

How can I tell which DWG version a file was saved in?

Every DWG begins with a six-character ASCII version code held in its first six bytes, such as AC1032 or AC1014. Open the file in a plain-text editor and those six characters are readable at the very start of the first line, or use a hex viewer to read offset 0 to 5. This viewer also reports the version code when the drawing loads. Match the code against the version table on this page to get the AutoCAD release.

Which DWG versions does this viewer open?

All seven format codes from AC1014 to AC1032: AC1014, AC1015, AC1018, AC1021, AC1024, AC1027 and AC1032. That covers every AutoCAD release from R14 in 1997 through AutoCAD 2026. Codes older than AC1014, such as AC1012 for R13, fall outside that range.

Do I need to save a drawing down to an older DWG format first?

No. Saving down exists because some tools only read older formats, and that is not the case here. A file in the current AC1032 format opens directly, so there is no need to ask the original author for a 2004 or 2013 copy before you can look at it.

Why does a file created last week report an old version code?

Because the format is chosen at save time, not by the calendar. AutoCAD can write earlier DWG formats deliberately, and many firms standardise on one format for exchange with consultants or manufacturing partners. A drawing edited in AutoCAD 2026 can legitimately report AC1027. The header code describes the format, not the age of the work.

Will DWG files from Civil 3D, Plant 3D or Advance Steel open?

The file itself opens, because these vertical products write the same DWG format codes as plain AutoCAD. Their custom objects are the issue: proxy and custom entities such as Civil 3D corridors and surfaces or Advance Steel connections do not render, so the drawing can look incomplete even though the version is fully supported.

The version is supported but part of my drawing is missing. Why?

Version support and entity support are two different things. External references are not resolved, so only the host drawing is shown; proxy and custom objects do not render; complex hatch patterns appear as boundary outlines only; custom SHX fonts are substituted; and DIMENSION entities in DWG files may not render. Check the layer panel first in case content is simply switched off, then try an ASCII DXF export of the same drawing, which goes through a different parser here.

What is a DWG File DWG vs DXF CAD File Formats DXF Viewer STL Viewer OBJ Viewer DWG to PDF Compare Drawings Embed Widget Sample Files

Check Your DWG in the Browser

Every format code from AC1014 to AC1032. Nothing to install, nothing uploaded.