FunscriptPreviewHandler is an open-source Windows Explorer extension that lets you preview your .funscript files without opening them in a separate application.
Renders .funscript heatmap directly in Windows Explorer’s preview pane
Metadata is also rendered for convenience
Integrates with Windows Explorer
Installation
Regular Users (Recommended)
Simply download and run FunscriptPreviewHandler-Setup.exe from the Releases page. The installer handles everything automatically.
Advanced Users
If you prefer manual installation, individual DLL files are provided:
FunscriptPreviewHandler.dll
Newtonsoft.Json.dll
SharpShell.dll
You will need to launch SharpShell Server Manager and install the FunscriptPreviewHandler.dll manually by clicking File > Load Server... inside Server Manager.
Note: Manual installation is only recommended if you understand Windows shell extensions and registry requirements.
How to Use
Install using the setup file
Open Windows Explorer
Navigate to a folder containing .funscript files
Select a .funscript file
The preview will appear in the preview pane (typically on the right side)
If you don’t see the preview pane, press Alt+P or go to View → Preview pane
System Requirements
Windows 10 or 11
.NET Framework 4.7.2 or newer
Source Code
The project is open source (MIT license) and available on GitHub.
Feedback
If you encounter any issues or have suggestions for improvement, please open an issue on GitHub or reply to this thread.
I hope you find this useful! Cheers. PS: This was inspired by @smeedler’s request for a way to see .funscript files without opening OFS.
Changelog
v1.0.2 - Theme toggle and resizeable metadata panel
v1.0.1 - Show extra metadata (performers, video URL, etc.) if available
This is a neat concept, although I hope some experienced coders can go over it and locate any flaws. (Or alternatively properly make a similar project without an over-reliance on LMMs.)
Letting LLMs handle the coding means you might not have a firm grasp of issues that may be present.
I probably shouldn’t have used the term vibe-coding and LLMs loosely in the post. I’ve removed it from the post to avoid future confusion.
LLMs helped a bunch overall, tho I’ve read over what was written.
It is relatively straightforward; heatmap rendering logic was largely ported from @defucilisfunMapper.ts (LLMs do great porting over maths) and metadata is read from the .funscript file and rendered in a second box under the heatmap.
That’s fair, as long as you’ve proofread the output and are aware of how everything functions I don’t have an issue with it.
LLMs can shortcut some research and typing, but it’s important to be familiar with the structure and potential issues.
Don’t know if anyone else is getting this issue recently but whenever I try to preview funscripts it doesn’t show and it only tells me the file could be harmful and to open it to view its contents. I tried uninstalling the extension and redownloading the latest version but still doesn’t work
hmm, looks like this is related to a recent Windows update breaking things. People across the world are affected with this, preview pane broke for other people for their PDF documents, Word, etc.
Seems you were affected as well.
There’s details about it in this thread from user Rez, Scroll down a bit, he’s one of the answers.
Excerpt:
The October 15, 2025 Windows update introduced a new security feature that flags certain files in the preview pane with the message:
The file you are attempting to preview could harm your computer. If you trust the file and the source you received it from, open it to view its contents."
This has disrupted workflows for many users who rely on the preview pane to quickly inspect files without opening them.
It’s likely tied to tightened security policies around file previews. Since it’s related to new protections against potentially malicious files, especially those downloaded from the internet or shared via network drives.
There are a couple options that are suggested in there as well.
