Guide

What is a JWW file?

JWW is the file format of Jw_cad, a free 2D CAD widely used in Japan for architecture and construction. AutoCAD and most other CAD programs cannot open JWW files directly. This site opens them in your browser and converts them to DXF, which AutoCAD and most CAD programs read.

View a JWW file

1. Open the JWW Viewer and drop a .jww file (or click to choose one). It works on Windows, Mac, iPhone, Android and tablets.
2. Switch between Layout1 (the printed sheet) and Model (real size). Use the mouse wheel or two fingers to zoom and drag to pan.
3. Click Measure and then two points. The points snap to line ends, circle centers and points.
4. Click Convert this file to DXF if you need the drawing in a CAD program.

Convert to DXF

1. On the converter, drop one or many .jww files (60 MB per file, no limit on the number of files).
2. Files are converted one by one. Download each DXF, or download everything as one ZIP (DXF files plus conversion reports).
3. The first time, the converter is loaded into your browser, which can take a few tens of seconds. Large drawings (tens of thousands of lines) take one or two minutes.

Opening the DXF in AutoCAD

• Model tab: everything is real size (1 unit = 1 mm). Measured lengths are real lengths.
• Sheets that mix scales: the main drawing stays in place; details at other scales (e.g. 1:3) and the title block (1:1) are real-size blocks named JWW_GROUP_…, placed to the right of the sheet.
• Layout1 tab: the paper size at 1:1 with one viewport per scale, matching the Jw_cad printout. Print from here.
• Construction lines are on layers ending in _補助線_印刷しない (“construction line, do not print”) and are not plotted.
• Layer names and text stay in Japanese. Text uses MS Gothic / MS Mincho, which are installed on Japanese Windows; on other systems AutoCAD substitutes a font.

DXF and JWW to PDF, images, JWW and DXF

• On PDF / Image, drop DXF or JWW files to preview them and convert to PDF, SVG, PNG, JPG, JWW or DXF.
• Area: a layout (paper space, clipped per viewport like a plot) or the model (whole drawing).
• Scale (model): fit to paper, or 1:1 to 1:1000; you are told when the drawing does not fit.
• Paper: the drawing’s sheet size or fitted to A4–A0. Color: color or black & white. Resolution (PNG/JPG): 150–600 dpi.
• DXF version: save a DXF again as R12–2018; JWW can be converted to DXF too.
• “Convert all with these settings (ZIP)” converts every file at once.

DXF to JWW (AutoCAD drawings for Jw_cad users)

• Drop DXF files (R12–2018) on DXF → JWW to get Jw_cad .jww files; several at once, downloadable as one ZIP.
• “Auto” scale picks a Jw_cad scale at which the drawing fits the chosen paper (A3 by default). Real sizes measured in Jw_cad do not depend on the scale.
• DXF layers become named Jw_cad layers; blocks stay blocks; dimensions, leaders, hatches, polylines and splines are exploded into lines, arcs, text and fills.
• Colors map to the nearest Jw_cad pen 1–8, widths to per-object line widths, line types to solid / dotted / chain. Fills keep their exact color.
• Characters Jw_cad cannot store (e.g. emoji) become “?” and are listed. Paper space is not converted.

DXF version

• Choose R12, 2000, 2004, 2007, 2010, 2013 or 2018 under the drop area. If unsure, use 2010.
• 2004, 2000 and R12 store text in Shift-JIS (Japanese code page); 2007 and later use UTF-8.
• 2000 and R12 have no true colors, so the nearest AutoCAD index color is used.
• R12 turns ellipses into polylines and fills into SOLIDs, has no line weights, and needs ASCII layer names (e.g. “0_0_図枠” becomes “0_0”; construction layers end in “_NOPLOT”).
• For every version the written DXF is read back and all dimension line lengths are checked.

Save as PDF

• Once a drawing is shown, choose the page (the drawing's sheet size, or fitted to A4/A3/A2/A1) and color or black & white, then click Save PDF. It works on the viewer and on the converter.
• Lines, dashes, fills and text are vectors; text can be selected and searched.
• Line widths are not reduced when fitting to a smaller page (as in Jw_cad printing). White screen colors print black. Construction lines and viewport frames are not printed.
• Text uses the standard PDF Japanese fonts (HeiseiKakuGo / HeiseiMin) without embedding, so your device's Japanese font is used to draw it.

Conversion report

Each converted file has a report: file names and SHA-256 hashes, a thumbnail of the sheet, the scales, every dimension compared with the length measured in the DXF, line weight changes, object counts and processing notes. Print it or save it as PDF.

Offline use

After the first visit, when “Works offline” appears at the top right, the site works without a network. In Chrome and Edge you can install it as an app from the address bar. Only the program is stored in the browser, never your drawings.

Supported

• Every JWW format: Jw_cad 2.30, 3.00 and 4.20 (files saved with “save as old version”), 6.x (the format of Jw_cad’s own sample drawings), 7 and 8
• Drawings with embedded pictures (Jw_cad 7 and later): the picture becomes a DXF image and its file goes into a ZIP together with the DXF — extract it and keep both in the same folder. Pictures also appear in the preview, PDF, SVG, PNG and JPG
• Italic and bold text (italic/bold text styles in the DXF)
• Dimensions inside blocks; construction points (on non-plot layers)

Not supported yet

• Drawings of the DOS version of Jw_cad (.jwc)
• Pictures that are linked rather than embedded in the drawing (the picture file is missing, so the file is held). Embed the pictures in Jw_cad before saving

Such files are not converted; the reason is shown instead. No incomplete DXF is produced.

Please note

Always check the result in your CAD program before use. See the terms.