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.PAS file extension

To open .PAS files on Windows, right-click the .pas file → Open with → choose a code editor to view it as text.

To open a .PAS file, use a text/code editor (for viewing) or a Pascal IDE such as Delphi or Free Pascal tools (for building/running). If you’re not sure what created it, open it as plain text first to confirm it is source code.

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Last updated: June 11, 2026 · Reviewed by Julian Stricker

What “reviewed” means on this page
  • Format fit: whether the “what is this file?” description 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; we remove fantasy menus and unsafe shortcuts.
  • 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: whether external links point to vendors, standards bodies, or other primary references where possible; we avoid inventing details we cannot ground.
  • Limits: this is clarity and safety-messaging QA, not a guarantee that every statement is exhaustive or that every binary you download is harmless.

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 .PAS files

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

Windows

  1. Right-click the .pas file → Open with → choose a code editor to view it as text.
  2. If it is a Delphi/Object Pascal unit you need to build, open it in Embarcadero Delphi/RAD Studio (it is the standard IDE that uses .pas units).
  3. If you only need to inspect the contents safely, choose an editor (not “Run”) so it opens as plain text.
Full Windows guide

Mac

  1. Open the .pas file in a code editor (any text editor that can handle plain text) to view the source.
  2. For compiling/building Object Pascal projects, transfer the project to a system with a Pascal toolchain/IDE available for your workflow (common Delphi use is Windows-based).
Full Mac guide

Linux

  1. Open the .pas file in a code editor from your file manager (Open With → a text/code editor).
  2. If installed, use a Pascal environment/tooling (for example Free Pascal–based workflows) to compile; otherwise, treat it as plain text for viewing.
  3. If your desktop doesn’t recognize .pas correctly, check the file’s association via the shared MIME database configuration used by your Linux desktop.
Full Linux guide

iOS

  1. Open the .pas file in the Files app with a text/code viewer; if it won’t preview well, share it to a dedicated text editor app or transfer it to a desktop to compile/run.
Full iOS guide

Android

  1. Open the .pas file with a text/code editor app to view it as plain text; for building/compiling, move the file to a desktop Pascal toolchain/IDE.
Full Android guide

Security notes

  • .PAS files are plain text source code, but they may be part of a project that builds an executable; treat code from untrusted sources as potentially harmful if compiled and run.
  • Prefer opening unknown .pas files in a text editor (view-only) first; avoid running build scripts or compiling code until you understand what it does.
  • Be cautious with IDE/project features that automatically run post-build steps or external tools—review project settings before executing anything from an untrusted codebase.

If you did not expect this file

This extension is usually plain data, text, or structured content—not a program by itself. The practical risk is social engineering (a scam attachment or misleading filename). For trusted senders you rarely need heavy-handed antivirus wording; use these tools when you want an extra check on unexpected downloads.

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Can't open this file?

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

Common reasons

  • The .PAS file opens in the wrong app (or as an unknown file)
  • It’s not actually Pascal source code
  • Compiler/IDE errors when building a .PAS file

Fix steps

  1. Use “Open with” and select a text/code editor to view the file content.
  2. If you regularly work with Pascal, set your chosen editor/IDE as the default app for .pas files.

OS-specific troubleshooting

What is a .PAS file?

.PAS is widely used for Pascal-family programming language source files, including Object Pascal used by Delphi. Embarcadero’s Delphi uses .pas for unit source files, and many editors treat it as a text-based code file. Because it is plain text source, the “format” is primarily the programming language syntax rather than a binary document structure.

Background

The .pas extension is strongly associated with Pascal source code and, in modern practice, Object Pascal. Delphi (part of Embarcadero RAD Studio) organizes code into units, and each unit is defined in its own .pas file; Delphi compilers expect unit source files with the .pas extension.

You’ll see .pas files in software projects (often alongside other project files) where they define program logic, classes, procedures/functions, and unit interfaces/implementations. While you can read .pas in any text editor, using an IDE can provide syntax highlighting, navigation, and the ability to compile.

On Linux desktops, file association often comes from the freedesktop.org shared MIME database, which maps extensions like .pas to MIME types and helps choose a default editor/IDE. On the web and in some tools, .pas is commonly labeled with the unregistered MIME type text/x-pascal rather than an IANA-registered standard type.

Common MIME types: text/x-pascal

Further reading

Authoritative resources for more details on the .PAS format.

Common .PAS issues

The .PAS file opens in the wrong app (or as an unknown file)

Your system may not have a Pascal-aware editor/IDE associated with .pas, so it defaults to an unrelated app or shows “unknown format.”

  1. Use “Open with” and select a text/code editor to view the file content.
  2. If you regularly work with Pascal, set your chosen editor/IDE as the default app for .pas files.

It’s not actually Pascal source code

Sometimes files are mislabeled or downloaded with the wrong extension; a .pas should typically be readable text containing Pascal/Object Pascal keywords (e.g., unit, interface, implementation, begin, end).

  1. Open the file in a plain text editor and verify it looks like Pascal source code.
  2. If it looks like binary/garbled data, re-download the file or ask the sender what program created it.

Compiler/IDE errors when building a .PAS file

A .pas file is usually part of a larger project (units depend on other units, project files, and library paths). Opening a single unit may not be enough to compile successfully.

  1. Obtain the full project (all referenced units and supporting files), not just one .pas file.
  2. In Delphi workflows, open the project in Delphi/RAD Studio rather than compiling a single unit in isolation.

FAQ

Is a .PAS file a “document” file?

Most commonly, no—.pas is widely used for Pascal/Object Pascal source code (including Delphi units). You can read it like a text document, but it is primarily programming source.

What program should I use to open .PAS?

For viewing, any text/code editor works. For Delphi/Object Pascal development, Delphi (RAD Studio) is a primary tool that uses .pas unit files.

Can I convert a .PAS file by renaming the extension?

No. Renaming changes only the filename extension. To change formats, you would need an export/conversion process, but source code is typically kept as text.

Why does my system label .PAS as text/x-pascal?

text/x-pascal is a commonly used (but unregistered) MIME labeling for Pascal source. MIME recognition and app association often come from desktop MIME databases and local configuration.

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