How to Open CRSWAP File: Recover or Delete Chrome Swap Files

What is a CRSWAP file?

A CRSWAP file is a temporary swap file that Chromium-based browsers (Google Chrome, Microsoft Edge, Opera) create when a website writes to a file on your disk. Web apps such as online text editors, note apps and design tools can ask permission to edit a file or folder you choose, through a browser feature called the File System Access API (available since Chrome and Edge 86). When the site saves, the browser does not touch your file right away. It writes the new content into a sibling file named after it, with .crswap added: notes.md gets notes.md.crswap in the same folder.

The web standard says changes made through a write stream "won't be reflected" in the real file until the stream is closed, and that this is "typically implemented by writing data to a temporary file". Chrome's temporary file is the .crswap. When the site finishes and closes the stream, Chrome moves the .crswap over the original, and the swap file disappears. You only ever see one if the save did not finish. Because the content is your own document under a temporary name, you don't need special software to open CRSWAP files.

How to open a CRSWAP file, step by step

Short answer: there is no special CRSWAP viewer, because the file is simply your document under a temporary name. To open CRSWAP files, rename a copy back to the original name and open it with the app that made it:

1. Close the web app's tab (or quit the browser) so nothing is still saving.
2. Copy both files, the original and the .crswap, to a safe folder such as your Desktop.
3. Check the .crswap with the free checker above: it shows the original name, the real type and whether the content looks complete.
4. Rename the copy from notes.md.crswap to notes.md (also drop a .1 or .2 if present), or click Download as… in the tool.
5. Open it and compare with the original. Keep whichever has your latest work, then delete the leftover .crswap.

Why do I have .crswap files?

You have .crswap files because a website you used in Chrome, Edge or Opera was saving a file in that folder and the save didn't complete. The browser names and creates them, not the app, so the app's own name never appears in the file name. Documented cases include:

• Logseq (web version, editing a local graph folder): users asked "What are crswap files?" in Logseq's GitHub issue #4466, and a maintainer replied that .crswap "is created by Chrome, not the Logseq app", pointing to interrupted Chrome file-system operations.
• vscode.dev (Visual Studio Code for the Web, with a local folder opened): the VS Code team added a default rule that hides *.crswap files from the file list on the web version, so you may only notice them in File Explorer or Finder.
• Construct 3 (browser-based game editor): forum users found project.c3p.crswap files after interrupted saves, and one bug report describes a 0 KB .c3p next to a roughly 300 KB .crswap that had to be renamed to recover the project.

Whatever app made it, you open CRSWAP files the same way (steps above). Any other web app that offers "Open folder", "Open file" or auto-save to a file on your computer can produce them in the same way. Each new write gets its own swap file, so if the first name is taken (for example by a leftover from an earlier crash, or the same file being edited in two tabs), Chromium inserts a number: notes.md.1.crswap, notes.md.2.crswap… up to 100 per file handle.

Why browsers use a swap file at all

Two reasons. First, your real file stays intact until the new version is fully written, so a crash mid-save can't leave you with a half-written original. Second, security: a Chromium engineer explained on the chromium-dev mailing list that the .crswap gives "local security scanning software the opportunity to examine the modified file" before it lands under a name other programs will open. Chromium's code hashes the swap file for Safe Browsing checks and, on Windows, can add the "downloaded from the internet" mark before the final move.

Which browsers create them

How to recover data from a CRSWAP file

The safest way to open a CRSWAP file after a crash is to rename a copy of it to the original file name. Its content is the version the web app was trying to save, so it is usually newer than the original next to it. Two details decide how much you get back:

• Whether the app kept the existing data. When a site opens the stream with the keepExistingData option, the browser first copies the original into the .crswap and the site then changes it. Otherwise the swap starts empty and the site writes the whole file from scratch. Either way, a finished swap file is a complete new version.
• Where the save stopped. If the browser crashed half-way, the .crswap ends early. Text files show everything up to the cut; images may show the top part; ZIP-based files (DOCX, XLSX, Construct .c3p) lose their index, which is written last. The checker on this page tells you which case you're in.

1. Close the tab of the web app that was editing the file.
2. Copy the .crswap and the original to a backup folder. Work on the copies only.
3. Drop the .crswap into the checker. If it says "Looks complete", click Download as… to save it under the original name.
4. If it says "Looks incomplete", still rename a copy and open it: text-based files (Markdown, JSON, code, CSV) are readable up to the cut. Paste the missing part back from the original if needed.
5. Open the recovered file in the same web app (or any program for that format) and check your latest changes are there.

Open CRSWAP files on Windows 11 and Windows 10

Windows hides known extensions by default, which makes it harder to open CRSWAP files: you may see notes.md twice. Turn extensions on first, then rename a copy:

1. In File Explorer, select View > Show > File name extensions (Windows 11). On Windows 10, tick File name extensions on the View tab.
2. Right-click the .crswap and choose Copy, then Paste in the same or another folder.
3. Select the copy, press F2 and delete .crswap from the end of the name (and the .1 if present). If the original is in the same folder, give the copy a different name, such as notes (recovered).md.
4. Confirm the "If you change a file name extension, the file might become unusable" warning with Yes, then double-click the file.

Open CRSWAP files on Mac

To open CRSWAP files on macOS, the steps are the same: duplicate, rename, open.

1. In Finder, choose Finder > Settings > Advanced and turn on Show all filename extensions, so you see the full .md.crswap name.
2. Select the .crswap and press ⌘+D to duplicate it.
3. Press Return on the duplicate, remove .crswap and choose Use .md (or the matching extension) when macOS asks.
4. Open the file. Quit the browser with ⌘+Q before deleting any leftover swap files; closing its windows doesn't quit it.

Linux and ChromeOS

To open CRSWAP files on Linux, use your file manager's Copy and Rename, or the cp command shown above. tail shows where a text file ends, and file notes.md.crswap reports the real type of a binary one. On a Chromebook, open the Files app, right-click the .crswap, choose Copy and Paste, then Rename the copy without .crswap. The checker on this page also works in Chrome on ChromeOS.

You won't normally find .crswap files on Android phones, iPhones or iPads: the browsers there don't let websites edit files in your folders this way.

Can I delete a .crswap file?

Yes. A .crswap is safe to delete once no browser tab is saving that file, and deleting it never affects the original. The only thing you can lose is the newer, unsaved version it may hold. Before deleting:

• Check the original has your latest work. If the .crswap is newer (later "Date modified") or larger, recover it first.
• Close the web app's tab or quit the browser if the file is in use. A swap that is still being written may be locked, and on Windows you can get "The action can't be completed because the file is open in" the browser.
• Empty (0-byte) .crswap files hold nothing and can always be deleted.

If you only wanted to open CRSWAP files to see what's in them, the checker does that without renaming or deleting anything. Cleaning up many at once? In File Explorer or Finder, search the folder for .crswap, check the dates, and delete the ones whose originals are up to date.

CRSWAP vs CRDOWNLOAD: what's the difference?

Both are temporary Chromium files that get renamed when an operation finishes, which is why they are often confused. They come from completely different features:

Swap files never show up in chrome://downloads, so you can't resume or open CRSWAP files from there. If your file ends in .crdownload, follow our guide to open CRDOWNLOAD files and resume downloads instead.

How to stop .crswap files from appearing

Normal saves remove their own .crswap, so leftovers come from interrupted saves. To avoid them:

• Wait for the save to finish before closing the tab, shutting down or putting the laptop to sleep.
• Don't edit the same file in two tabs at once; each writer gets its own swap file.
• Be careful with synced folders (Google Drive, OneDrive, Dropbox). Sync apps can pick up the .crswap while a save is running, and a file the sync app is holding may not be movable or deletable until it lets go.
• Keep the browser updated, since fixes to the File System Access API arrive with browser updates.
• Block a site from editing files: in Chrome go to Settings > Privacy and security > Site settings > File editing and choose not to allow sites to edit files, or click the site-information icon next to the address and change File editing for one site. The app then can't save to your disk, so only do this for sites you don't need.

Common CRSWAP problems and fixes

Most problems people hit when they try to open CRSWAP files come from a save that was interrupted, or from another program holding the file.

The original file is 0 KB and won't open

The save truncated the original but the swap never replaced it, or the app wrote an empty file. Rename a copy of the .crswap to the original name: in the Construct 3 bug report above, that's exactly what restored the project.

Google Drive or OneDrive can't delete or sync the .crswap

The browser may still hold the file. Close the tab or quit the browser, then pause the sync client, delete or recover the swap, and resume sync.

The app shows old content after a crash

The app is reading the original, which still holds the last completed save. Your newer edits are in the .crswap. Recover them as described in the recovery steps, then reopen the folder in the app.

Renamed file says "corrupted" or "can't be opened"

If you open a CRSWAP file after renaming it and the app calls it damaged, the save stopped part-way and the format needs its last bytes (ZIP-based documents, PDFs). Use the checker to confirm, keep the original, and try a repair tool for that format. For plain text, open it in a text editor instead; everything up to the cut is readable.

Antivirus flagged a .crswap

That is the scanning step working as designed: the browser exposes the swap file so security software can inspect it before it replaces your file. If you trust the web app, restore the file from quarantine; if not, delete it.

Related file extensions

These guides cover the browser temp files and the formats you most often find when you open CRSWAP files.

Sources and technical references

.crswap is a Chromium implementation detail, not a public file format, so these are the primary sources we checked on October 4, 2026.

• Chromium source: file_system_access_file_handle_impl.cc — builds the swap name with .crswap, inserts .N on collisions, creates it in the same directory and copies the original when keepExistingData is set.
• Chromium source: file_system_access_file_handle_impl.h — max_swap_files_ = 100 and the comment explaining swap files.
• Chromium source: file_system_access_safe_move_helper.cc — hashing for Safe Browsing checks, quarantine and the final move of the swap file.
• chromium-dev: why FileSystemWritableFileStream writes to .crswap files — a Chromium engineer on the security-scanning reason.
• File System Standard (WHATWG) — changes aren't reflected in the file until the stream is closed; typically implemented with a temporary file.
• MDN: FileSystemFileHandle.createWritable() — keepExistingData and "siloed" mode, where each writer has its own swap file.
• Chrome for Developers: The File System Access API — changes are not written to disk until the stream is closed; Chrome and Edge 86+.
• Can I use: File System Access API — support in Chrome, Edge and Opera; none in Firefox, Safari or Chrome for Android.
• Brave issue #18979 — the API is off by default in Brave and can be enabled with a flag.
• Logseq issue #4466: "What are crswap files?"
• VS Code issue #229076 — references the commit "web - filter out *.crswap via files.exclude".
• Construct bug #3989 and Construct forum: .c3p.crswap — real cases of leftover swap files.
• USENIX Security 2023 paper on browser-based ransomware — independently describes the .crswap naming and swap behavior.
• Google Chrome Help: Change site settings permissions — the File editing permission.
• Microsoft Support: Common file name extensions in Windows and Apple: Show or hide filename extensions on Mac.

Frequently asked questions