How to identify file formats at a glance for digital archivists in 2026

Steps for archivists to identify file format thumbnails in Windows File Explorer, what to prepare, which tools to check, and mistakes to avoid.

By 2Dex · 2026-10-14

2Dex is published by the makers of SageThumbs 2K, RēDesign and VectorMagik, which are compared here alongside other tools.

For digital archivists, a thumbnail add-on for Windows turns each file's format into a picture you can read without opening it. SageThumbs 2K is one add-on that adds File Explorer thumbnails for 363 file types that Windows can't render natively, including camera RAW, Photoshop PSD, HEIC/AVIF, and video.^[1]

Option	Formats you can see at a glance	Personal use	Commercial use
SageThumbs 2K	Adds thumbnails for 363 file types including camera RAW, Photoshop PSD, HEIC/AVIF, and video ^[1]	Free for noncommercial use ^[1]	US$2.99 a month, or US$49 once with 12 months of updates ^[1]
Other thumbnail or preview add-ons	Not published	Not published	Not published

What you need before you start

Reading a folder and telling every file's format apart at a glance takes a little groundwork first. Work through this list.

A Windows PC you can change. Some add-ons need administrator rights to install. If your work machine is locked down, look for an option that offers a portable version.
The exact formats in your archive. List the extensions you hold, from plain text and spreadsheets to design, CAD and video files. Each tool names the formats it reads, and you want yours on that list.
Your Windows version and chip type. Find out whether you run Windows 11 and whether the processor is x64 or ARM64, since installers differ by chip.
Your kind of use. Unpaid archive work and paid consulting contracts are often licensed differently. Decide which applies before you install anything.
A test folder. Pick a folder with a handful of files, ideally one of every format you store. You will check the result there.
A backup of anything irreplaceable. Thumbnail tools should only read your files, but keeping a backup copy of anything you cannot replace is a sensible habit.

Finally, close any open File Explorer windows so you can restart them cleanly after the install.

Step by step

These steps work the same way whichever thumbnail add-on you pick.

Open your test folder and note the current state. Switch the view to Large icons or Extra large icons from the View menu. If you see generic file icons for a format, thumbnails are missing for that type.
Check that thumbnails are allowed. Open Folder Options, go to the View tab, and make sure the box that says to always show icons and never thumbnails is not ticked. This setting hides thumbnails for every file type, whatever you install.
Pick an add-on. Compare the formats each one lists against your own file extensions. Also read its licence terms for personal or commercial use.
Download from the maker's own page. Choose the installer that matches your chip type, x64 or ARM64. If you cannot install software, look for a portable download.
Install it and restart File Explorer. Signing out and back in, or restarting the PC, also works. Windows keeps old thumbnails in a cache, so the first look may still show plain icons.
Reopen the test folder. Give the thumbnails a moment to draw. A folder of large video or CAD files takes longer than one of small text files.
Clear the thumbnail cache if icons stay plain. Use Disk Cleanup and tick thumbnails, then reopen the folder.
Check every format family. Open one file from each kind you hold. A rare or new format can be missing from an older tool until it updates.
Check where the files live. If your material sits in a synced cloud folder, confirm that thumbnails appear there too, and that the tool does not pull down files you wanted to keep online only.
Look at the details. Compare the small preview against the file itself. Wide-gamut images and some videos can look different in a small preview.

Tools that can do it

Facts are published here for only one tool, so the comparison is short. For any other option, such as a codec pack or another thumbnail add-on, check its own page for the formats it names, its Windows version support, its licence and whether it needs administrator rights.

### SageThumbs 2K

SageThumbs 2K is made by the team that publishes this site. It adds File Explorer thumbnails for 363 file types that Windows can't render natively, including camera RAW, Photoshop PSD, HEIC/AVIF, and video.^[1] For design and CAD files such as Photoshop, Affinity, AutoCAD DWG and CorelDRAW, it pulls the embedded preview straight out of the file with no rendering needed.^[1] It runs on Windows 11, with separate installers for x64 and ARM64.^[1] You can use a portable zip that needs no admin rights.^[1]

For archivists, a few other behaviours matter. It adds image dimensions, EXIF camera details and audio tags to Explorer's Details pane, hover tooltips and sortable columns for formats Windows can't read itself.^[1] Pressing the Space bar opens an instant preview, on by default unless another Space-bar previewer is installed.^[1] From the right-click menu you can convert images, resize, rotate or flip them losslessly, and combine images into a PDF or CBZ for a single record.^[1] Thumbnails also work in OneDrive and Synology Drive folders, and it never downloads online-only files just to draw a thumbnail.^[1] SageThumbs 2K says a corrupt or malicious file can't crash File Explorer, because it runs separately from Explorer and reads files in a sandbox.^[1] The licence is the PolyForm Noncommercial License 1.0.0, and it is source-available.^[1]

On cost, it is free for personal, noncommercial use.^[1] Commercial use needs a per-installation licence: US$2.99 a month, or US$49 once for a perpetual licence with 12 months of updates.^[1] Business installs get a 7-day evaluation with every feature, after which thumbnails and previews stop until a licence key is entered.^[1]

Common mistakes to avoid

Skipping the Folder Options check. If Explorer is set to show icons only, no add-on can bring thumbnails back. Check this setting first.
Judging the result too early. Explorer keeps a thumbnail cache. Restart File Explorer and, if needed, clear the cache before you decide the tool failed.
Installing the wrong build. Match the installer to your chip type. An x64 build on an ARM64 machine, or the reverse, can stop it working.
Ignoring the licence. Free personal terms do not automatically cover paid consulting work. Read the terms and decide which applies before you rely on a tool.
Testing with only one file. Formats are written in many different ways. Test at least one file from each format family you hold.
Trusting thumbnail colour for a final record. A thumbnail is a quick guide for sorting. Judge colour and details in the file itself.
Forgetting synced folders. Check how a tool treats cloud files before pointing it at a folder that holds online-only material.
Installing several thumbnail tools at once. Two add-ons handling the same format can compete. Remove one before you try another.

Frequently asked questions

How to identify file formats at a glance in Windows?

Giving each file a recognizable thumbnail means installing an add-on that reads the formats you hold. First check that thumbnails are not turned off in Folder Options, then pick a tool and list the formats you need against the ones it names. Switch the folder to a large icon view and open one file from every format family to confirm each one draws a preview before you rely on it.

Can SageThumbs 2K preview design and CAD files?

Yes. It pulls the embedded preview directly out of design and CAD files such as Photoshop, Affinity, AutoCAD DWG and CorelDRAW with no rendering needed.^[1] It also adds File Explorer thumbnails for 363 file types that Windows can't render natively, including camera RAW, Photoshop PSD, HEIC/AVIF, and video.^[1] Install it, restart File Explorer, and check one file of each format you archive.

Is SageThumbs 2K free for archivists?

It is free for personal, noncommercial use under the PolyForm Noncommercial License 1.0.0.^[1] Commercial use needs a per-installation licence: US$2.99 a month, or US$49 once for a perpetual licence with 12 months of updates.^[1] Read the terms to see which category your work falls into before relying on it.

Can a thumbnail tool be installed without admin rights?

Some tools offer a portable download. SageThumbs 2K lists a portable zip that needs no admin rights.^[1] For any other tool, check its page for a portable option or for the rights its installer asks for before you start on a locked-down work PC. That check matters when your archive machine is managed by an IT team that limits what staff can install.

Do thumbnails appear for files in a shared archive folder?

With SageThumbs 2K, thumbnails also work in OneDrive and Synology Drive folders, and it never downloads online-only files just to draw a thumbnail.^[1] For any other tool, check how it treats online-only files before pointing it at a synced folder. SageThumbs 2K says a corrupt or malicious file can't crash File Explorer, because it runs separately from Explorer and reads files in a sandbox.^[1]

It is free for personal, noncommercial use under the PolyForm Noncommercial License 1.0.0. ^[1]

Try SageThumbs 2K

Sources

SageThumbs 2K's own description of itself (the product of this site's publisher)