.NB file extension

To open .NB files on Windows, install and open a Wolfram notebook application that supports .nb (for example, Mathematica, Wolfram Desktop, or Wolfram Player).

To open a .NB file, use a Wolfram notebook app such as Mathematica, Wolfram Desktop, or Wolfram Player. On mobile, .NB files typically aren’t supported directly—transfer the file to a desktop Wolfram product to view and run it.

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Last updated: June 11, 2026 · Reviewed by Julian Stricker

What “reviewed” means on this page

Format fit: whether the “what is this file?” description matches common real-world use of the extension, including category, typical MIME types, and aliases.
Opening paths: whether Windows / macOS / Linux steps read plausibly for current OS dialogs and default apps; we remove fantasy menus and unsafe shortcuts.
Security framing: whether risk notes match the extension class (for example executables vs plain data) and whether affiliate wording does not contradict the security section.
Sources and further reading: whether external links point to vendors, standards bodies, or other primary references where possible; we avoid inventing details we cannot ground.
Limits: this is clarity and safety-messaging QA, not a guarantee that every statement is exhaustive or that every binary you download is harmless.

Full methodology in the Imprint — The Imprint also states where AI is used and what that does—and does not—replace.

Open on your device

Choose your operating system for a dedicated step-by-step opening guide.

How to open .NB files

Use these platform-specific instructions to open .NB files safely.

Windows

Install and open a Wolfram notebook application that supports .nb (for example, Mathematica, Wolfram Desktop, or Wolfram Player).
In the Wolfram app, use File > Open and select the .nb file (or double-click the file if the app is already associated with .nb).
If you’re prompted about converting the notebook version, allow the app to open/convert a copy if you need to preserve the original.

Full Windows guide

Mac

Install and open a Wolfram notebook application that supports .nb (for example, Mathematica, Wolfram Desktop, or Wolfram Player).
Use File > Open in the Wolfram app to open the .nb file (or Control-click the file and choose Open With, then pick the Wolfram app).
If the notebook opens with a compatibility/version message, follow the prompt to open or convert as needed.

Full Mac guide

Linux

Open the .nb file using a Wolfram notebook application available on your system (for example, Mathematica or Wolfram Desktop).
From the Wolfram app, choose File > Open and select the .nb file.
If your desktop environment doesn’t recognize .nb, open it from within the Wolfram app rather than from the file manager.

Full Linux guide

iOS

iOS typically won’t open .nb notebooks natively; transfer the file to a desktop computer and open it with Mathematica, Wolfram Desktop, or Wolfram Player.

Full iOS guide

Android

Android typically won’t open .nb notebooks natively; transfer the file to a desktop computer and open it with Mathematica, Wolfram Desktop, or Wolfram Player.

Full Android guide

Security notes

.NB notebooks can contain Wolfram Language code; only evaluate/run content from sources you trust, especially if the notebook asks you to execute cells.
Be cautious with notebooks that reference external files, network resources, or packages you don’t recognize; review the notebook content before running computations.
If you need to inspect a notebook safely, open it first for viewing and read the cells before evaluating any code.

If you did not expect this file

This extension is usually plain data, text, or structured content—not a program by itself. The practical risk is social engineering (a scam attachment or misleading filename). For trusted senders you rarely need heavy-handed antivirus wording; use these tools when you want an extra check on unexpected downloads.

Avast

Avast offers free and premium antivirus software that protects against viruses, malware, ransomware, and phishing. Scan files before opening them to ensure safety.

Norton

Norton 360 delivers comprehensive antivirus protection, VPN, and identity theft monitoring. Scan files for threats before opening to keep your device secure.

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Can't open this file?

These are the most common causes and fixes when .NB files fail to open.

Common reasons

The .NB file opens as an unknown file or in the wrong app
Version/compatibility prompt when opening a notebook
Notebook displays but won’t evaluate code
Importing/processing .NB in Wolfram Language fails

Fix steps

Install a Wolfram notebook application that supports .nb (Mathematica, Wolfram Desktop, or Wolfram Player).
Open the file from inside the Wolfram app via File > Open, or change the file association to the Wolfram app.

OS-specific troubleshooting

What is a .NB file?

.NB is the native notebook format for the Wolfram System notebook interface. It stores notebook content (text, formatting, and Wolfram Language input/output) in a form that Wolfram products can open and, depending on the product, evaluate. The format is used across Wolfram Language products and is described as cross-platform by Wolfram.

Background

.NB files are Wolfram Notebooks: interactive documents that combine narrative text with Wolfram Language code and computed results. They are the standard working format for Mathematica and related Wolfram notebook-based products, and the .nb extension is commonly associated with Wolfram Language notebooks.

Wolfram documents NB as the native notebook file format and provides built-in mechanisms to work with it (for example, importing a notebook file via Wolfram Language). Wolfram also documents notebook opening behavior, including that notebooks commonly use the .nb extension and that Wolfram notebook tools may perform version-related conversion when opening older/newer notebooks.

In practice, .NB is most often encountered when someone shares a Mathematica/Wolfram notebook for analysis, teaching materials, demonstrations, or reproducible computational work. If you don’t have a Wolfram notebook application installed, the file may appear “unknown” to your operating system even though the file itself is valid.

Common MIME types: application/vnd.wolfram.mathematica

Common .NB issues

The .NB file opens as an unknown file or in the wrong app

Your system may not have a Wolfram notebook application installed or may not have .nb associated with it.

Install a Wolfram notebook application that supports .nb (Mathematica, Wolfram Desktop, or Wolfram Player).
Open the file from inside the Wolfram app via File > Open, or change the file association to the Wolfram app.

Version/compatibility prompt when opening a notebook

Wolfram notebook tools may prompt to convert notebooks depending on the notebook’s version and your installed product version.

Follow the in-app prompt to open/convert the notebook; if offered, choose an option that preserves the original file (open a copy) when you need to keep it unchanged.
If conversion fails, try opening the notebook in a different Wolfram product/version that matches the notebook’s origin more closely.

Notebook displays but won’t evaluate code

Some Wolfram products or configurations may allow viewing but limit evaluation features, or the notebook may require resources/packages not present on your system.

Confirm you are using a Wolfram product that supports notebook evaluation for your workflow (not just viewing).
Ask the sender what Wolfram product/version the notebook was created with and whether it depends on specific packages or data.

Importing/processing .NB in Wolfram Language fails

Programmatic import may fail due to file corruption, incomplete transfers, or unexpected notebook content.

Try opening the notebook interactively in a Wolfram notebook application; if it won’t open, re-download or obtain a fresh copy.
Use Wolfram Language’s documented NB import pathway (e.g., Import["file.nb"]) and verify the path/filename is correct.

FAQ

What program opens .NB files?

.NB files are Wolfram Notebooks. Wolfram products such as Mathematica, Wolfram Desktop, and Wolfram Player are designed to open them.

Is .NB the same as a generic “data file”?

Most commonly, .NB refers to a Wolfram Notebook (not a generic data container). It’s a document format used by Wolfram notebook interfaces and may include code and results.

Can I open .NB files on iPhone or Android?

Mobile operating systems typically don’t support .nb notebooks directly. A practical approach is to transfer the file to a desktop and open it with a Wolfram notebook application.

What is the MIME type for .NB?

A registered media type commonly associated with Mathematica/Wolfram notebook-related content is application/vnd.wolfram.mathematica.

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