.CURL file extension

To open .CURL files on Windows, if you have Curl® tools/RTE installed, try opening the .curl file from the application that supports Curl applets (or use its Open function).

To open a .curl file, use Curl® tools/runtime that understand Curl applets (MIME: text/vnd.curl). If you only need to read it, you can open it as plain text in a text editor, but it will not “run” without Curl support.

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Last updated: April 30, 2026 · Reviewed by Julian Stricker

What “reviewed” means on this page

Format fit: whether the “what is this file?” description plausibly matches common real-world use of the extension, including category, typical MIME types, and aliases.
Opening paths: whether Windows / macOS / Linux steps read plausibly for current OS dialogs and default apps. Not every step was tested on every OS version.
Security framing: whether risk notes match the extension class (for example executables vs plain data) and whether affiliate wording does not contradict the security section.
Sources and further reading: external links should point to vendors, standards bodies, or other primary references where possible; not every detail is individually sourced.
Limits: this is clarity and safety-messaging QA, not a guarantee that every statement is exhaustive or that every binary you download is harmless. Pages without “Reviewed by” have not been through this editorial pass yet.

Full methodology in the Imprint — The Imprint also states where AI is used and what that does—and does not—replace.

Open on your device

Choose your operating system for a dedicated step-by-step opening guide.

How to open .CURL files

Use these platform-specific instructions to open .CURL files safely.

Windows

If you have Curl® tools/RTE installed, try opening the .curl file from the application that supports Curl applets (or use its Open function).
If you only need to view the contents, right-click the file → Open with → choose a text editor to inspect it as text.
If the file was meant to run in a browser context, confirm it is being served/handled as text/vnd.curl (otherwise it may not load correctly).

Full Windows guide

Mac

If you do not have Curl® tooling available on macOS, open the file in a plain-text editor to view its contents.
For running/testing the applet, transfer the file to a system/environment that supports Curl applets and handles text/vnd.curl appropriately.

Full Mac guide

Linux

Open the .curl file in a text editor to review the applet source/content.
To run it as intended, use a Curl-capable environment and ensure any web delivery uses the MIME type text/vnd.curl.

Full Linux guide

iOS

iOS typically won’t run Curl applets; use the Files app to share/export the .curl file to a text editor app for viewing, or transfer it to a desktop Curl-capable environment to run it.

Full iOS guide

Android

Android typically won’t run Curl applets; open the .curl file in a text editor app to view it, or move it to a desktop Curl-capable environment to execute/test it.

Full Android guide

Security notes

.curl files are Curl applets (active content) rather than simple static documents; treat them like code and only run them if you trust the source.
When receiving a .curl file from someone else, inspect it in a text editor first to understand what it contains before attempting to execute it in a Curl-capable environment.
If hosting .curl files on a server, set the correct content type (text/vnd.curl) deliberately; mislabeling content types can cause unexpected handling by clients.

Can't open this file?

These are the most common causes and fixes when .CURL files fail to open.

Common reasons

The .curl file opens as plain text or “unknown format”
Curl content does not load correctly in a browser or web view
File association points to the wrong app

Fix steps

Open it in a text editor if you only need to read the contents.
If you need to run the applet, use a Curl-capable runtime/tooling environment rather than expecting a standard document viewer to open it.

Recover a deleted or lost .CURL file

If the file was deleted by mistake or the drive was formatted, data recovery software may be able to get it back. Stop writing to that drive right away, because new data can overwrite what you want to recover.

MiniTool Power Data Recovery

Windows software that recovers deleted or lost files from PCs and external drives such as HDDs, SSDs, USB drives and memory cards, after deletion, formatting or a crash.

Wondershare Recoverit

Windows and Mac software that recovers deleted or lost files from computers and external drives such as HDDs, SSDs, USB drives and SD cards.

We may earn a commission when you use affiliate links. This supports our free file extension guides.

OS-specific troubleshooting

What is a .CURL file?

A .curl file is a Curl applet file (often referred to as “Curl - Applet”) that contains Curl code/content for the Curl runtime environment. When embedded in web content, Curl applets are associated with the registered media type text/vnd.curl. In practice, .curl files may be treated as text files by editors, but they represent active applet content when executed by Curl-capable environments.

Background

The .curl extension is associated with Curl® applets. Curl documentation shows applets stored as files named with the .curl extension (for example, start.curl) and describes their contents as applet code/content used by the Curl environment.

In browser-embedded scenarios, Curl’s documentation specifies that embedded Curl content should use the MIME type text/vnd.curl. This MIME type also appears in reference MIME/extension tables and in the IANA media types registry vendor tree listing for vnd.curl.

From a practical standpoint, a .curl file is most useful in workflows that still involve Curl applets and the Curl RTE/plugin ecosystem. Outside that ecosystem, the file can usually be inspected as text, but it will not behave like a typical “document” (such as PDF or DOCX) and may contain executable applet logic rather than static content.

Common MIME types: text/vnd.curl

Common .CURL issues

The .curl file opens as plain text or “unknown format”

Many systems do not have Curl® applet support installed, so the file is treated as an unknown type or just a text file.

Open it in a text editor if you only need to read the contents.
If you need to run the applet, use a Curl-capable runtime/tooling environment rather than expecting a standard document viewer to open it.

Curl content does not load correctly in a browser or web view

Curl documentation specifies that embedded Curl content should be served/identified with the MIME type text/vnd.curl; incorrect MIME type handling can prevent proper loading.

Verify the server/content-type configuration is using text/vnd.curl for .curl resources.
Confirm the client environment has the required Curl support for embedded content (where applicable).

File association points to the wrong app

The OS may associate .curl with a generic editor or another program, which is fine for viewing but not for executing the applet workflow.

Choose “Open with” and select a text editor for safe inspection, or the correct Curl-related tool if installed.
Avoid renaming the extension to force an app to open it; instead, use the appropriate application’s import/open feature.

FAQ

What does a .curl file contain?

It typically contains a Curl applet—code/content intended to be used by the Curl runtime environment, not a conventional office-style document.

What MIME type is associated with .curl files?

The registered/commonly referenced MIME type is text/vnd.curl.

Can I convert a .curl file to PDF or DOCX?

Not directly as a standard conversion, because .curl is applet source/content. Your best option is to open it as text for reading, or use Curl-specific tooling/workflows to render/export any content if your environment provides that.

Is .curl related to the cURL command-line tool?

Despite the similar name, the sources here describe .curl as a Curl® applet file type (text/vnd.curl), not a file format for the cURL networking tool.

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