When you click a file with the preview window open, windows will show you a preview if windows knows how to do it. But files like .json and .py will not preview.

It would be sometimes useful in the open dialog of any editor to preview a script before opening it. Most open dialogs will inherit the windows explorer preview settings but ....

How do you make windows associate .py files as text like files for the preview pane?

  • 3
    Possible duplicate of Windows 7 - Preview other file types as text in Preview Pane May 8, 2018 at 18:37
  • Please review the answer(s) in the linked question. If they answer your question, great. If they do not, please edit your question to indicate how your question differs and note how the linked answers do NOT meet your needs. May 8, 2018 at 18:38
  • The accepted answer in the link is wrong so im not sure i should say that solved the problem. However one of the answers in that thread was correct the 2nd answer. May 9, 2018 at 6:38
  • 1
    @music2myear I have added my answer which references your link but i used a different solution which i think is cleaner and more useful to others. Is that acceptable ? May 9, 2018 at 14:24

4 Answers 4


The answer came from this link this link as music2myear mentioned but the accepted answer in that link did not work for me.

What worked for me was 2nd answer in the thread. Member user255627 points out the correct key is HKEY_LOCAL_MACHINE\SOFTWARE\Classes\.py which requires attribute PerceivedType REG_SZ text.

I created an attribute in this key with reg command. You can substitute .py with any extension type and enable a bunch of extensions this way. No need for a external program as mentioned in other thread.

from windows command prompt cmd.exe

reg add HKLM\SOFTWARE\Classes\.py /v PerceivedType /t REG_SZ /d text

If you don't have reg permissions to HKLM (local machine) you can use HKCU (current user)

reg add HKCU\SOFTWARE\Classes\.py /v PerceivedType /t REG_SZ /d text

You can query like this.

reg query HKLM\SOFTWARE\Classes\.py /s

(Default)    REG_SZ    Python.File
PerceivedType    REG_SZ    text

Thanks for the help guys. very useful.

  • thanks. any one-liner to also remove an extension like .py from preview?
    – GorvGoyl
    Jun 15, 2021 at 17:34
  • 1
    delete works but you probably want to delete just the value and not the whole key because keys may contain other values. So use value as well as the key reg delete HKCU\SOFTWARE\Classes\.py /v PerceivedType Jun 16, 2021 at 15:11

Several years back I hunted for additional preview handlers and found some:

  • from MSDN Magazine (see list below)
  • some build with/for Delphi

I'm still searching for online references, they might be no longer available.

Aside from this there is a preview-handler-association-editor you can download and use to add extension to a present handler (i.e. add .ini, .inf extension to a text handler.)

I wrote a batch file to enumerate currently present handlers in the registry. It appends found handlers to the batch file itself and displays them afterwards.

 @Echo off
Echo ============================================ >>%0
Echo Computername: %ComputerName% Date: %Date% %Time:~0,6% >>%0
reg query "HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\PreviewHandlers" >>%0
More +9 <%0
goto :EOF

Sample output:

Computername: xxxxx Date: 2018-05-08 20:47: 

    {13D3C4B8-B179-4ebb-BF62-F704173E7448}    REG_SZ    Windows Contact Preview Handler
    {1531d583-8375-4d3f-b5fb-d23bbd169f22}    REG_SZ    Windows TXT Previewer
    {53BEDF0B-4E5B-4183-8DC9-B844344FA104}    REG_SZ    Microsoft Windows MAPI Preview Handler
    {85862EDA-F507-4d5b-ACA9-BB2C34A85682}    REG_SZ    Microsoft XPS Rich Preview Handler
    {8a7cae0e-5951-49cb-bf20-ab3fa1e44b01}    REG_SZ    Windows Font previewer
    {92dbad9f-5025-49b0-9078-2d78f935e341}    REG_SZ    Microsoft Windows Mail Mime Preview Handler
    {a42c2ccb-67d3-46fa-abe6-7d2f3488c7a3}    REG_SZ    Windows RTF Previewer
    {b9815375-5d7f-4ce2-9245-c9d4da436930}    REG_SZ    Microsoft Windows Mail Mime Preview Handler
    {BFD468D2-D0A0-4bdc-878C-E69C2F5B435D}    REG_SZ    Microsoft Windows Mail Html Preview Handler
    {E64164EB-1AE0-4C50-BAEF-A413C2B3A4BC}    REG_SZ    Microsoft 3MF Shell Thumbnail and Preview Handler
    {f8b8412b-dea3-4130-b36c-5e8be73106ac}    REG_SZ    Microsoft Windows Mail Html Preview Handler
    {031EE060-67BC-460d-8847-E4A7C5E45A27}    REG_SZ    Windows Media Player Rich Preview Handler
    {691100A7-2A53-456B-BFE5-6BA17A0AB768}    REG_SZ    Delphi Asm Preview Handler
    {B8961094-8033-4D5B-AAB3-A6BCC76EB7A5}    REG_SZ    Delphi Cpp Preview Handler
    {5B96A782-E9C7-4620-B9DA-4B219BF97AB3}    REG_SZ    Delphi Xml Preview Handler
    {AD8855FB-F908-4DDF-982C-ADB9DE5FF000}    REG_SZ    Delphi Preview Handler
    {f2d43dd7-1233-4d5f-9032-b82a570aee81}    REG_SZ    MSDN Magazine RESX Preview Handler
    {21c532d1-6f1a-4f53-a000-0468a4337ab5}    REG_SZ    MSDN Magazine MSI Preview Handler
    {574fffaa-17f6-44b1-a1b4-177ab5900a51}    REG_SZ    MSDN Magazine PDF Preview Handler
    {df9e65b0-7980-4053-9fcf-6e9af953a9f4}    REG_SZ    MSDN Magazine Binary Preview Handler
    {853f35e3-bd13-417b-b859-1df25be6c834}    REG_SZ    MSDN Magazine ZIP Preview Handler
    {739972dc-dad1-4e8c-bb82-113de4b16b13}    REG_SZ    MSDN Magazine Resources Preview Handler
    {2d6dad69-f296-4be0-ab9e-6ed642aef76b}    REG_SZ    MSDN Magazine Strong Name Key Preview Handler
    {8fd75842-96ae-4ac9-a029-b57f7ef961a8}    REG_SZ    MSDN Magazine Internet Explorer Preview Handler
    {47f228f7-5338-4bb4-af7b-7b52278e1095}    REG_SZ    MSDN Magazine CSV Preview Handler
    {e90a8adf-a1a7-42e8-87b9-02b3bfee31f7}    REG_SZ    MSDN Magazine Serialized Ink Preview Handler
    {dec9ca47-e4cd-4eed-8f1b-b0567a489f0a}    REG_SZ    MSDN Magazine XAML Preview Handler
    {DC6EFB56-9CFA-464D-8880-44885D7DC193}    REG_SZ    Adobe PDF Preview Handler for Vista
    {84F66100-FF7C-4fb4-B0C0-02CD7FB668FE}    REG_SZ    Microsoft Word previewer
    {21E17C2F-AD3A-4b89-841F-09CFE02D16B7}    REG_SZ    Microsoft Visio previewer
    {65235197-874B-4A07-BDC5-E65EA825B718}    REG_SZ    Microsoft PowerPoint previewer
    {00020827-0000-0000-C000-000000000046}    REG_SZ    Microsoft Excel previewer
  • Thank you @LotPings the delphi preview handler looks cool and it may be something ill add in future. I tried the association tool you mentioned and it created more registry entries. looks like i only needed the one to make it work though. May 9, 2018 at 15:16
  • 1
    This result is what I needed, but also, that is a cooool batch file.
    – dgo
    Mar 29, 2021 at 20:45

I just installed Windows PowerToys which includes a "File Explorer add-ons utility". This utility provides syntax colored previews for "developer files". Supposedly it knows over 150 file types.

  • Thank you, very helpful, i deinstalled them because Windows got snap layouts, but didn't know about this useful feature. Syntax highlightiing works like a charm for python and contrary to the above hacks, it honors my dark theme settings. Jun 20, 2022 at 21:47
  • Ah, that's the one I did, thx. And still replying to the same answer :) Jul 26, 2023 at 15:45

PowerShell script:

[microsoft.win32.registry]::SetValue("HKEY_CURRENT_USER\Software\Classes\.json", "PerceivedType", "text")

Replace .json with required file extension: .py, .php or .whatever

Author: Daryn

  • Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.
    – Community Bot
    Feb 12, 2023 at 17:03
  • This worked for several different extension. But the preview for *.html does not show as text, instead it persists in showing an HTML preview. Any Suggestions?
    – fishjd
    Jan 9 at 19:00

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