mFax for Windows: The Native Fax App for Windows 10 & 11

By Alexey Spasskiy · Published August 13, 2026 · Updated August 13, 2026 · 9 min read

Quick answer: mFax for Windows is a native desktop fax app on the Microsoft Store, listed as mFax - Send and Receive FAX and published by Octagon Lab. It is free to install (about 46 MB), runs on Windows 10 version 17763.0 or higher and on Windows 11, and ships for both x64 and ARM64. It sends faxes over your internet connection — no modem, no landline, no printer driver. Sending faxes and getting your own fax number require a paid subscription.

For most of the last decade, "fax from Windows" meant one of two disappointing answers. Either you opened a browser tab and used a web service, or you bought a USB fax modem, found an analog phone line that still worked, and wrestled with Windows Fax and Scan — a built-in app that has shipped since Vista and still expects hardware PCs stopped including around 2010.

That changed on 10 August 2026, when mFax for Windows arrived on the Microsoft Store. It is a real Windows application: it lives in your Start menu, accepts files dragged out of File Explorer, follows your light or dark theme, and does the whole job — compose, edit, sign, send, receive — without a browser and without a single piece of hardware.

This page is the honest version of the store listing. What the app does, exactly how to install and use it, where the limits are, and what it deliberately does not do.

What mFax for Windows Is

It is the desktop version of the same mFax service that runs on iPhone, Android, Mac and the web. One account covers all of them, and your fax history syncs across every device you sign in on — a fax you send from your PC at 9 a.m. is in your phone's history at lunch.

Mechanically, it works like every internet fax service: your document is converted to fax-ready pages, transmitted to the recipient's fax machine over the phone network by the service, and confirmed back to you. The difference is where you do the work. Instead of a web form in a tab, you get a native window with drag-and-drop, clipboard paste, keyboard shortcuts and a resizable navigation pane.

System Requirements and Store Facts

How to Install It from the Microsoft Store

Sending Your First Fax

The Page Editor: Fix and Sign Before You Send

This is the part a browser tab does not give you, and the reason to install the app if you fax more than twice a year.

Before a fax goes out you can reorder, rotate, duplicate, delete and extract pages. You can draw on them in seven ink colors and add text captions — enough to circle a figure, initial a box, or write a note in a margin. And you can sign with your mouse, trackpad or pen, then drag the signature into position on the page.

That last one quietly removes the worst workflow in office life: printing a contract so you can sign it, scanning it back in, and hoping the scan is legible. Undo and redo work throughout, so an experiment with page order costs nothing.

Getting a Fax Number and Receiving Faxes

Sending is only half of it. In the app you can get your own fax number: pick a country, then a state or area, and filter the available list by the digits you want. A subscription is required for a dedicated number.

Incoming faxes land in the app and open in a proper desktop PDF viewer — zoom, fit to width, fit to page, rotate, and page thumbnails down the side. It reads like a document, not like a preview thumbnail in a web form. If you are weighing this against the other ways to take delivery of a fax on a PC, our guide to receiving a fax on your computer covers the alternatives.

Delivery Receipts and Failures in Plain English

Every transmission is tracked, and the delivery receipt downloads as a shareable PDF — which is the artifact that matters when you are proving to the IRS, a court clerk or an insurer that a document arrived.

Failures are handled better than most fax software manages. Instead of a numeric error code you get the actual reason: busy line, no answer, no fax signal, or number out of service. Those four cover the overwhelming majority of failed faxes, and each one tells you what to do next — retry in fifteen minutes, or go find the correct number.

Teams: One Number, One History, Several People

You can create an organization from inside the app, invite colleagues by email, and share a single workspace, fax number and history between them. The navigation pane switches between your personal workspace and the organization's, so a shared clinic or firm number does not get tangled up with your own faxes.

For teams that need more than shared access — a signed BAA for HIPAA, multiple seats, audit trails — that runs on mFax Business, which is usage-based and starts from about $9/mo billed annually.

Your Account and Your Data

Sign-in is email-only, with a guest mode if you want to try the app before attaching an identity to it. From the app you can see every device signed into your account and revoke any of them, and you can delete your account and its data outright. Both controls live in the app rather than in a support ticket queue.

The Limits, Stated Plainly

The hard numbers: 60 pages per fax and 20 MB per file. Sixty pages covers nearly everything an individual sends — a tax return, a full medical record request, a signed lease — but if you are transmitting a deposition, split it. For the file size ceiling, an image-heavy scan is usually the culprit; run it through the free PDF optimizer before you add it.

mFax for Windows vs. Windows Fax and Scan

Windows Fax and Scan is not going away and this article is not pretending it is worthless — if you already own a working USB fax modem and pay for an analog landline, it sends faxes for free. The question is whether that describes you.

If you are switching off the built-in tool because it stopped working rather than because you were shopping, our guide to Windows Fax and Scan alternatives starts from the failure — no modem detected, missing from Optional Features, VoIP line — and includes the scanner half, which no fax app replaces.

For the full method-by-method walkthrough of both, see our guides to faxing from Windows 11 and faxing from Windows 10, or the deep dive on Windows Fax and Scan on Windows 11. If you have not settled on a kind of app yet, how to pick a fax app for Windows sorts the four categories against your hardware, and best fax software for Windows ranks the named services on price and compliance.

Should You Install It?

Install it if you fax from a PC more than once or twice a year, you are on an ARM machine where the built-in tool does not exist, you sign documents and are tired of the print-sign-scan loop, or you want faxes to arrive somewhere other than a web page.

Skip it if you fax once and never again — the browser version at mFax.to does the same job with nothing installed — or if you are on a locked-down work PC where the Microsoft Store is disabled. The browser route is the same account and the same history either way.

Get mFax for Windows

Install mFax for Windows from the Microsoft Store, drag your document into the window, type the fax number, and send. Free to install, no modem, no phone line, and a native ARM64 build for Copilot+ PCs.

Prefer not to install anything? Open mFax in your browser instead — same account, same fax history. And if a whole team needs the number, mFax Business adds seats, a signed BAA and audit trails, built to the exact size you need from about $9/mo.