A downloadable extension for Windows

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SaiThumbs is a FREE Windows shell extension that will allow you to have thumbnails for .sai files produced from SYSTEMAX's PaintToolSai!

Download the appropriate archive for your architecture of Windows(find out which architecture you're running here!). Chances are you are running an x64 bit version of Windows so you'd download SaiThumbs-x64.zip.

  1. Unzip the archive somewhere the SaiThumbs.dll file can stay
    1. You can drag it next to your sai.exe installation( such as in C:/PaintToolSAI/ ) for convenience of keeping everything sai-related in one place.
    2. Copy "install.bat" and "uninstall.bat" along with it so you can easily enable/disable it
  2. Double click on "install.bat" to install
  3. That's it!

Double click on "uninstall.bat" for when you want to remove SaiThumbs.

Simple as that!

This project is open source!

Be sure to send any bugs and issues to the official issue tracking page
StatusIn development
Rated 5.0 out of 5 stars
(18 total ratings)
Tagspainttool-sai, sai, thumbnail


Download NowName your own price

Click download now to get access to the following files:

SaiThumbs-x64.zip 47 kB
SaiThumbs-x86.zip 41 kB
SaiThumbs-x64_arm64.zip 40 kB

Development log


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I reinstalled windows 10 on my pc recently and for some reason, saithumbs hasn't worked since. I made sure I downloaded the right version and everything, but none of the SAI thumbs are loading at all. I noticed the message I get when clicking either install or uninstall changed, though. It's the exact same message for both and looks like this. I wondered if this is normal.

Hey there! Another user here might have had a similar issue as yours. Does enabling the "EnableLUA" registry-setting fix the issue? It might be that it does not have proper permissions. Be sure to run the installation scripts as an administrator as well.

hello! ive been using this for a bit but a couple months ago it stopped working, any .sai files created after it stopped working wouldnt show the thumbnail, i tried uninstalling and reinstalling but that only got rid of the rest of the thumbnails, is there a way to get it to work again? thanks!

Hey! Just to make sure, are you using saithumbs-x64.zip or saithumbs-x86.zip? When you extract the installer files and run the installer, is the .dll located somewhere stable such as next to your Sai installation folder?

Have you tried clearing your thumbnail cache? You can clear your thumbnail cache by running "Disk Cleanup" and selecting "Thumbnails" before cleaning. This should get Windows to re-generate all of the thumbnails entirely and invalidate any that it may already have.

Hi, im using the x64 version, keep the files in a folder within my sai installation folder

I did try clearing the thumbnail cache but that didnt seem to do much

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Hmm still looking into this, what version of Windows are you currently on? Had you upgraded your Windows version before it stopped working?

im using windows 10, version is 21H2

did have to update to it, and the extension stopped working maybe 2 or 3 months after the update

I've uploaded a new build with some more recent fixes that you may try out! Let me know how it goes. 

You can be sure that you have the latest build by right-clicking the .dll file and going into the "Details" panel to ensure the year is 2023 rather than 2018(The previous build was from 2018 and lots of fixes have happened since then.


You are a genuine lifesaver, thank you for this! I just rediscovered all my old art as sai files and there are literally over 5000, so this will help sort and organize it!

You're so very welcome! So glad to help!

thank you very much for providing this extension! 

You're so very welcome!

Thank you very much. Helps me a lot.

You're very welcome!


Sai 2 please!!!


Stop nagging him. Especially in a time when people have vastly different problems. I made this account just to write this comment. The request was already made, and the developer gave a very nice answer. It is regrettable that no thumbnailing support for Sai 2 is available; but that's not Wunkolo's fault. If you want something from him, consider donating. If all he gets from his work are begging comments, then it's not attractive to do something for others. I understand your sentiment, because the lack of thumbnails is negatively affecting me, too. But I don't nag, and neither should you.


Oh wow, I found my way back to this website through a completely unrelated post, I left a comment a year ago and never returned. Its interesting you interpreted saying 'please' and showing interest in something as 'nagging'.  Its hilarious you felt the need to write this ๐Ÿคฃ Also that you only replied to me and none of the other people mentioning SAI2. Anyway, chow!

Hey, sorry if this is irrelevant, but is there a way to extract the thumbnail image?  the SAI file is corrupted but for some very strange reason its thumbnail is still working, so I was hoping to extract the thumbnail image ....

You might be able to use a tool like https://thumbsviewer.github.io/ to open your thumbnail cache and extract it!

Otherwise I would probably have to write something using libsai just to extract the thumbnail if there is a need for it.

Interested in knowing how your sai file is corrupt though! Are Sai and Sai2 unable to open it?

Thanks for replying. I think there's an error on my drive. Sai 1 tells me "failed to open canvas". SAI2 opens it, but the image is damaged. The canvas has turned blank. However, the thumbnail image is still prefectly intact somehow. Thumbsviewer doesn't work because apparently the thumbnail image for SAi isn't in that folder.

Maybe I can release a standalone thumbnail extraction tool or general purpose dumping tool just for people trying to somewhat recover corrupt sai files.

Email me the .sai file and I can see what I can do!

(wunkolo at gmail)

Oh wow, thank you very much for the offer. I had given up it being recovered because I could only find PSD recovery softwares online. I'll send you the file.


Made an account just to comment; this has been AMAZING for me for my SAI 1 files, is there a possibility of there ever being a version of this that will do this for SAI 2 files?


Strong possibility!

I am currently trying to fix some bugs in the backing library that I have made for Sai and then I can move on to doing Sai2 if there is a demand for some additional tooling around it!


That'd be awesome, I recently  moved to using SAI2 so having this work for SAI2 files would be such a lifesaver for me.  Thanks for the reply!


I also made an account just to comment, thank you so much for making Saithumbs! It's been incredibly helpful for me and reminded me of long forgotten sketches that I never exported. I also just moved to Sai2, so I would definitely appreciate a version for Sai2 if you have the chance!


I came here just to agree with others, I would love a Sai2 thumbnail tool!


Yeah, this was a lfiesaver for Sai 1! but moving over to sai 2 is goign to be rough without any thumbnails


will heavily consider it!

I still have work to do before i consider my sai 1 research "done" and then ill move on to Sai 2!


I'd love Sai2 support!! I've retired the original Sai and moved to Sai2, so this'd be amazing.

here to root for that sai2 thumbnail tool as well :D


Yes! Please, please make it happen T_T

Amazing work!


Isn't SAI a paid product? Why the f*** isn't this supported out of the box? Why do YOU need to come along and fix it for them?

I believe that Sai is made by a single developer; and I assume that making shell extensions and coding drawing applications are quite different challenges. In addition, Sai's price is quite low.


Really looking forward to a potential fix for sai2-files :3

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Great extension :) Glad i helped fix the issue.


my life has been saved



(1 edit)

Hi, I'm having trouble with this, could you help?

The issue is I keep getting  this error and I don't know what to do or what I did to make it not work.

I installed it before and it worked fine, now after I did a factory reset of my computer, it won't work. 

Currently tracking this error over here: https://github.com/Wunkolo/SaiThumbs/issues/2

Trying to figure out what's causing it but there's some input there that you may tryyy

i made an account just to reply to this because i was having the same issue

i clicked "uninstall" and was met with a popup telling me to extract all the files, which i did to a folder under the same name; everything looked Exactly the same. then i tried to install again and it worked! i hope this works for you too

idk if its relevant or not but im running a 64 bit system


I made an account just to say a big ol' THANK YOUUUUU!! 

this is incredible, and I'm so so thankful for this! it'll make organizing my files through Explorer, rather than through Sai, sooo much easier ;u; 

also, I tried to pay through Paypal but it's telling me "We can't process your payment right now, so please try again later. We're sorry for the inconvenience." :<  

do you know why that might be? you deserve my DOLLARSS 

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Oh man I have no idea why...

This seems to be an issue that some other users ran into when trying to send me money through PayPal and I haven't noticed any consistency between them all to identify why this might be happening..

Maybe this page can work?


Thank you so much for this. This is a blessing in these dark times. Thank you 1000 times.

Awesome work! Do you think you'll be able to make ".SAI2" files work with this too?


I've reverse engineered Sai 2 a bit but not enough to map out the newer sai2 file format yet.. Since sai2 is actively being developed too I'll very likely have to "wait" for Sai 2 development to "settle down" for a little while before I go diving into the file format since one update SYSTEMAX makes can potentially break any confident research and tools I made at a specific version...

I'll look into it more in the future since the file format is probably not going to be changing drastically any time soon but we'll see!

Do you know about how different the settings2.ssd file is in SAI 2? I wanted to make a brush import/export tool. I have been working on decrypting the file for the last couple days before I came across this.

I haven't had much motive to reverse engineer Sai2 that much since Sai1 is still very much more popular but it possibly uses some improvements on the Sai1 format.

Well, I'll keep working on it, unfortunately my reverse engineering skills are terrible so it's really slow progress haha. I'd love to work with you if you're interested but I understand there's not much purpose yet. What tools did you use to reverse engineer SAI? I'm using IDA + WinDbg and a crappy hex editor... This page isn't great for extended talking though, email me if you want (myusername)@gmail.com.