memfile

Easy RAM disk for Windows. Create an arbitrarily-sized in-memory volume in milliseconds and get a real Windows file path inside it that any application (VLC, Photos, ImageGlass, Audacity, Python, anything) can read and write.

Backed by WinFsp via a native Rust PyO3 extension.

Why

Sometimes you need a file to exist on the filesystem, ONLY because some other app simply doesn't have the ability to open it from a memory location. If you want to write a script or an executable temporarily simply to execute it and then delete it, this is perfect. If you want easy media previews, like images, videos, and support all file formats, this is perfect, just write to the ram disk and have the OS open it in whatever is the default media viewer. Writing any of that to disk both wastes valuable SSD writes AND wastes time since ram is much much faster to write and read from. memfile gives you a real path backed entirely by RAM:

import memfile

with memfile.Volume(size_mb=64) as vol:
    path = vol.write("clip.mp4", data)   # real path like R:\clip.mp4
    os.startfile(path)                   # opens in the native player
# volume + its contents vanish on exit — zero disk writes

A Volume doesn't need a with block — a bare one lives like a bare open(), until you .unmount() it, drop it, or the process exits (it's auto-reclaimed on exit, even on a hard kill):

vol = memfile.Volume(size_mb=128)   # stays mounted
...
vol.unmount()                       # or just let the process end

Temp files on RAM

Drop-in replacements for the tempfile functions that put the file on a RAM disk instead of the on-disk system temp dir — same arguments, same return objects:

import memfile, subprocess, sys, os

with memfile.NamedTemporaryFile(mode="w", suffix=".py", delete=False) as f:
    f.write("print('hello from RAM')")
    script = f.name                 # e.g. R:\tmpabcd.py — in RAM
subprocess.run([sys.executable, script])
os.remove(script)

Also memfile.TemporaryFile, mkstemp, mkdtemp, TemporaryDirectory.

Mount as a folder (no drive letter)

Instead of a drive letter, a volume can mount at a folder path. A folder mount creates no drive letter and no volume-arrival broadcast, so — unlike a drive-letter mount — it never wakes idle disks (e.g. a backup HDD spinning up on every mount), while still being visible across integrity levels. Recommended for background/elevated services:

with memfile.Volume(size_mb=64, folder=True) as vol:
    print(vol.path)                 # e.g. C:\Users\me\AppData\Local\memfile\mounts\<id>\
    vol.write("clip.mp4", data)
# the folder is created on mount and removed on unmount

Pass folder="C:\\some\\path" to choose the location (must not already exist, or be an empty directory).

Requirements

• Windows (x64)
• WinFsp (installed automatically) (one-time, requires admin once). After that, creating and destroying volumes needs no elevation.

Installation

pip install memfile

License

memfile is licensed under the MIT License (see LICENSE).

It links the WinFsp DLL at runtime under the terms of the WinFsp FLOSS License Exception:

WinFsp - Windows File System Proxy, Copyright (C) Bill Zissimopoulos. https://github.com/winfsp/winfsp

WinFsp is a separate work (GPLv3 with a FLOSS exception) and must be installed separately by the end user. memfile does not redistribute or modify WinFsp.