How to open files your computer can't open, without installing

How to open a file your computer doesn't recognize: the short answer

Most of the time the file is perfectly fine; what's missing is the program that knows how to read it. Instead of installing Photoshop, AutoCAD, Outlook or Python just to take a peek, upload the file to the right AtlasDocs viewer, click "Open" and see the content on screen. Everything is read on your own device; nothing is sent to a server. For PDFs, photos, audio, video, e-books and CSV spreadsheets, there is a separate set of viewers: how to view files online.

Which file types you can view

• Photoshop (.psd and .psb): the flattened image, with its dimensions and layer count, and a "Download as PNG" button.
• CAD drawing (.dxf): zoom with the mouse wheel, drag to pan and "Recenter"; save with "Download image (PNG)" or "Download vector (SVG)."
• 3D model (.stl, .obj, .glb, .gltf): rotate and zoom the part; "Download snapshot (PNG)" saves the angle you chose.
• Jupyter notebook (.ipynb): text, code and each cell's results (tables, charts and images), with no Python installed.
• Email (.eml and Outlook .msg): subject, from, to, cc, date, message body and attachments with a "Download" button.
• XML invoice (Brazilian NF-e and NFS-e): issuer, recipient, items or service, taxes, total and the access key with a "Copy" button.

View a file, step by step

1. Open the viewer for the type of file you received (Photoshop, CAD, 3D, notebook, email or invoice).
2. Upload the file: drag it onto the "Drag your files" area or click "Select files." It appears in a list.
3. Click "Open" next to the file. Large files (a PSD of several hundred megabytes, a large 3D model) take a few seconds.
4. See the content on screen and, if you like, download the image (PNG or SVG) or the attachment using each viewer's buttons. "Back" returns to the list.

CAD drawings: what opens, what doesn't, and the way around .dwg

The CAD viewer opens .dxf, the exchange format every CAD program can export. It shows the geometry (lines, arcs, circles, curves, polylines) and counts elements and layers. It's a visual preview: text labels, dimensions and hatches are not drawn (the screen warns that some labels may be missing), so don't conclude the plan "came out wrong" because of that. Got a .dwg, AutoCAD's internal format? The file is recognized but not opened here yet: the screen explains how to open the drawing in your CAD program, use "Save as" (or Export), choose .dxf as the format and upload the .dxf. If you have no CAD program at hand, AtlasDocs itself converts DWG to DXF, PDF or PNG, but that conversion runs on our server; the steps are in the guide How to open DWG without AutoCAD.

If you only need an image of the drawing to paste into a document, a presentation or an email, the DXF → PNG and DXF → SVG converters do that without opening the viewer, even for several drawings at once ("Convert N drawings"). They draw only the geometry, like the viewer, and warn on screen when something is skipped: "N elements were left out (text, dimensions or hatches): the converter draws geometry only." Resolution, background and the details of each format are in the guide How to convert DXF to SVG or PNG.

3D models: rotate, zoom and take a snapshot

3D-printing and modeling files (.stl, .obj, .glb, .gltf) open in a scene where you drag to rotate and scroll to zoom. The viewer shows the triangle count and warns when the model is large and may be slow on weaker devices. The "Download snapshot (PNG)" button saves the current view, handy for sending to a client or for a listing.

Jupyter notebooks without Python

An .ipynb is the code notebook used in data science. Without Jupyter installed, it's just an unreadable text file. Here you see the explanatory text, the code and each cell's saved outputs: tables, errors, charts and images. Remote images are blocked to protect your privacy; nothing leaves your device.

Emails saved as .eml or .msg

Files in .eml (the standard of almost every email program) and .msg (from Outlook) show up as attachments in legal cases, receipts and forwards. The viewer shows subject, sender, recipients, cc, date and the message body, with remote images blocked. Attachments appear in a list, each with a "Download" button.

XML invoices, made readable

Brazilian electronic invoices arrive by email as XML, a pile of code in Notepad. The viewer recognizes goods invoices (NF-e) and service invoices (NFS-e) and lays out number, series, issue date, issuer, recipient (or provider and customer), items or service, taxes such as ICMS and ISS, discount, freight and total. The access key has a "Copy" button, ready to paste into the tax authority's lookup page. An XML that isn't an invoice opens too, as an organized tree. Note: the viewer shows what the XML says; it doesn't validate the invoice with the tax authority.

Common problems and limits

• "This is a .dwg file": not an error. Export to .dxf in your CAD program and upload the .dxf.
• Missing text on the plan: the CAD viewer and converters draw only the geometry; dimensions, text and hatches are left out.
• A Photoshop file with dozens of layers or a 3D model with millions of triangles: slow, and may freeze on phones. Use a computer.
• Invoices: amounts and names come from the file, with no official validation. To confirm authenticity, look up the access key on the tax authority's site.
• No viewer edits: to change the file, you still need the original program.
• On a phone, the CAD drawing opens and you can drag it, but zoom only works with the mouse wheel: to explore the details, use a computer.

All these viewers run in your browser: the file is read on your own device and never sent to any server. Ideal for a design you don't want to expose, an invoice with your data or a confidential email.

Next time a "can't open this file" shows up, try the right viewer before installing anything. Almost always it's just a matter of opening it with the tool that understands that format. Word, Excel and PowerPoint have their own viewer, which opens the file on our server: how to open Word, Excel and PowerPoint online without Office.