Open PF files in your browser
Windows keeps a .pf file of each program it starts, to start it faster the next time. See what ran and when, right here. Nothing leaves your device.
Or drop it anywhere on this page
What you'll see
Your prefetch file opens as the program it's for, when it ran and what it loaded.
- How often it ran • The last eight times
- The files and folders it loaded
- Its volume • Serial number and when it was formatted
- Nothing in it runs
About PF
Windows XP brought prefetch in 2001: in C:\Windows\Prefetch, Windows keeps a file for each program it starts, named for the program and a hash of its path, like NOTEPAD.EXE-D8414F97.pf, and uses it to load what the program needs before it asks. Windows 10 and 11 pack them with Microsoft's LZ77+Huffman.
A prefetch file holds the program's name, how many times it ran and when it last ran, up to eight times since Windows 8, the volumes it ran from with their serial numbers, the folders it used and the files it loaded in its first seconds.
Filepeek unpacks it with its own LZ77+Huffman decoder and shows the program, its runs with their times in UTC, its volume and every file and folder it loaded, all of it as a tree too. Nothing in it runs.
Windows prefetch file
.pf
Format
- MIME type
- application/octet-stream
- Made by
- Microsoft
- Released
- 2001
Inside the file
- Holds
- A program's runs and files
- Runs
- The count and the last eight times
- Packed
- LZ77+Huffman, Windows 10 on
- Made by
- Windows, XP on
Opens in every browser
Filepeek reads prefetch files in Chrome, Edge, Firefox and Safari, on any computer or phone. On their own, browsers only download them.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Apps that open PF
- WindowsNirSoft's WinPrefetchView, free
- MacNo app built in opens it
- iPhone and iPadNo app opens it
- AndroidNo app opens it
Questions
How do I see when a program last ran?
Drop its .pf from C:\Windows\Prefetch on this page. Its card shows how many times it ran and the last times it ran, up to eight.
Why does a prefetch file start with MAM?
Windows 10 and 11 pack prefetch files with LZ77+Huffman, under a MAM header. Filepeek unpacks it on its own, on any computer.
Why are there so few prefetch files?
Windows keeps up to 1,024 of them since Windows 8, and 128 before, letting the oldest go. Some computers turn prefetch off, and then Windows keeps none.