← LISP Vault

AUTOLISP PROTECTION GUIDE

How to Protect AutoLISP Source Code

The simplest way to share an AutoLISP tool without giving users the readable source is to package the .lsp file as a protected DLL or ARX plug-in. LISP Vault does this in a browser and can add an optional expiry date.

Protect an LSP fileSee how it works
Quick answer

Upload your LSP, choose DLL + LSP or ARX Beta, select an optional expiry, and download the protected result. Users load it with AutoCAD's APPLOAD command and run the original command name.

Why protect an LSP file?

A normal AutoLISP file is plain text. Anyone who receives it can open it, copy the implementation, remove licensing checks, or redistribute it. Packaging the routine reduces direct exposure when you need to send a trial, deliver work to a client, or distribute an internal CAD tool.

How it works

  1. Upload an AutoLISP .lsp file up to 2 MB.
  2. Choose an output: DLL + LSP or ARX Beta.
  3. Set an expiry by date, time, and time zone—or choose no expiry.
  4. Create and download the protected package.
  5. Test it in AutoCAD before delivering it to another user.
OPTION 1

DLL + LSP

Download a protected DLL and a small loader LSP. Keep them together unless you configured a specific DLL folder, then load the LSP with APPLOAD.

BETA

ARX

Download one file named like example.lsp.arx and load it directly with APPLOAD. No separate loader LSP is needed.

ARX Beta compatibility

ARX Beta is intended for AutoCAD and Civil 3D 2025–2026 on Windows. The current beta supports balanced LISP containing at least one top-level c: command. Command names must use ASCII characters, and command definitions cannot require input arguments.

What the protection does—and does not do

LISP Vault encrypts and packages the routine so the original source is not delivered as a readable LSP. Expiry checks are included in the generated package and run locally. This is a practical barrier against casual copying, but it is not a promise that reverse engineering or clock manipulation is impossible.

Frequently asked questions

Can an AutoLISP file be protected without sharing the source?

Yes. LISP Vault packages the source into a protected DLL with an LSP loader or, for compatible files, a single ARX plug-in. This reduces direct source exposure, although no software protection can guarantee that reverse engineering is impossible.

Does the original AutoCAD command name stay the same?

Yes. Supported top-level AutoLISP commands keep their original command names, so users can run them as usual after loading the generated package.

Can I add an expiry date to an AutoLISP tool?

Yes. You can select a date, time, and time zone. The generated package checks the expiry locally when it runs. You can also create a package without an expiry.

Which AutoCAD versions are supported?

The current service supports AutoCAD and Civil 3D 2025–2026 on Windows.

What is the difference between DLL + LSP and ARX?

DLL + LSP provides a protected DLL and a small loader LSP. ARX Beta produces one .lsp.arx file that loads directly through APPLOAD without a separate loader LSP.

Protect your AutoLISP file

Create a protected package in a few steps.

Open LISP Vault

Always keep your original source and test generated files in the exact AutoCAD environment where they will be used. See the Terms of Use and Privacy Policy.