✅ Completely free — No cost, ever
✅ Free to use — For personal, educational, or commercial purposes
✅ Free to modify — Change the source code for your needs
✅ Free to distribute — Share copies with others
✅ Access to source — The complete source code is publicly available
⚖️ Share-alike — If you distribute modified QET, you must share your changes under GPL too

What "Free" Means

The GPL uses "free" in two senses:

No cost — You never pay for QElectroTech
Freedom — You have freedom to use, study, modify, and share the software

Your Rights Under GPL v2

What You Can Do

✅ Use freely — Run QElectroTech for any purpose with no restrictions
✅ Study the source — Read and understand how it works
✅ Modify it — Change the code to fit your needs
✅ Redistribute — Share copies with others
✅ Sell it — Distribute (modified or unmodified) commercially

No licensing fees — None now, none ever, guaranteed by GPL

Your Obligations

If you distribute QElectroTech (modified or unmodified), you must:

Include the GPL license — Provide a copy with the software
Document changes — If modified, clearly mark what changed
Provide source code — Make the source code available to recipients
Use the same license — Modifications must stay under GPL v2
Acknowledge copyright — Include "© 2007-2026 The QElectroTech Team"

Important: These obligations only apply if you distribute the software. Using it privately has no obligations.

Common Scenarios Explained

Personal Use

Your situation: You use QET to create electrical diagrams for your projects.

Your rights:

✅ Download and install QET
✅ Create and save unlimited diagrams
✅ Modify QET's code for personal use
✅ No cost, no licensing fees
✅ No restrictions whatsoever

Your obligations: None.

Educational Use

Your situation: You're a teacher using QET in a classroom or students learning with it.

Your rights:

✅ Students can use QET for coursework
✅ Create custom elements for teaching
✅ No licensing complexity
✅ Affordable alternative to commercial tools
✅ Access to source for learning

Your obligations: None (unless you redistribute).

Professional Use (Unmodified)

Your situation: Your company uses QET to create diagrams professionally.

Your rights:

✅ Install on multiple computers
✅ Use for client projects
✅ Sell diagrams and documentation created with QET
✅ Your work is yours to keep
✅ No licensing fees or restrictions

Your obligations: None (you're not distributing QET itself).

Your diagrams are yours: The GPL only applies to QElectroTech software, NOT to diagrams you create with it. You own your work completely.

Professional Use (Modified)

Your situation: Your company modifies QET to add custom features and wants to distribute the modified version.

Your rights:

✅ Modify QET as needed
✅ Use internally without restrictions
✅ Sell software based on modified QET
✅ Customize for client needs

Your obligations:

Must provide source code to recipients
Must license modifications under GPL v2
Must document changes made
Must include license and copyright notice
Modifications cannot be proprietary

Key point: You can profit from software based on QET, but you cannot make it proprietary. Others gain the same rights you did.

Creating Custom Elements

Your situation: You design custom electrical symbols to share.

Your rights:

✅ Create any element libraries you want
✅ Distribute elements publicly
✅ Keep them private or share with team
✅ Sell element libraries
✅ Choose your own license for elements

Your obligations: None (elements are not code, so GPL doesn't apply).

Note: Elements themselves are not GPL; you can license them differently than QET.

Using QET in Commercial Products

Your situation: You develop an automation tool that uses QET libraries.

Before you proceed: Consult with a lawyer about GPL implications for your specific case.

General guidance:

If you statically link to QET or redistribute QET code:

Your product may need to be GPL as well
You must provide source code
You must license under GPL v2 or compatible license

If you use QET as a separate tool:

Fewer GPL implications
But still must comply with GPL for QET
Consult legal counsel for your specific situation

What GPL Does NOT Do

Your Diagrams Are NOT GPL

The GPL applies to QElectroTech software, not to diagrams you create:

Your .qet files belong to you
You can use them however you want
You can keep them private or publish
You can sell diagrams created with QET
No GPL restrictions on your work
You have complete ownership

Private use has no obligations
Only applies to distributions
Internal company use is unrestricted
No requirement to publish changes unless you distribute

It Doesn't Prevent Commercial Use

You can use QET commercially
You can sell software based on QET
You can profit from your work
No licensing fees or restrictions
No vendor lock-in

For Contributors

Contributing Code

If you contribute code to QElectroTech, you agree that:

Your code will be GPL v2 — Becomes part of the shared project
You retain copyright — You still own copyright to your contributions
QET Team can use it — They can modify and redistribute your code under GPL
Others get your improvements — Your contributions benefit the entire community

Why GPL? Ensures improvements stay free for everyone.

Contributing Elements

If you contribute element libraries:

You choose the license — Elements aren't code, so pick your own terms
QET can redistribute — Once shared publicly, QET may include in collections
You retain credit — Recognized as the creator
Community benefits — Your designs help other users

Full License Text

For the complete official license text, see:

LICENSE file on GitHub — Official QET license
GNU.org GPL v2 — Full license text and FAQ
TL;DR Legal GPL v2 — Quick summary

Attribution

If you use QElectroTech, we appreciate (but don't require) attribution:

In a project:

This project uses QElectroTech, licensed under the GNU General Public License v2.0

In documentation:

Diagrams created with QElectroTech, an open-source electrical schematic editor licensed under GPL v2.

Simple:

Powered by QElectroTech

Why GPL?

GPL ensures that:

✅ Freedom persists — Software stays free for everyone forever
✅ Improvements benefit all — Enhancements go back to community
✅ No vendor lock-in — You're never locked into one company
✅ Transparency — Source code is always available
✅ Democratic development — Community-driven, not corporate-controlled
✅ Trust — No hidden code or proprietary restrictions

The GPL protects the freedom of the software and the people who use it.

Frequently Asked License Questions

Q: Can I use QET at work?

A: Yes, absolutely. Commercial use is explicitly allowed.

Q: Can I sell diagrams made with QET?

A: Yes. Your diagrams are yours; the GPL doesn't apply to them.

Q: Do I need to pay for QET?

A: No, never. QET is free both in cost and in freedom.

Q: Can I modify QET for my needs?

A: Yes. You can modify it however you want for personal/internal use.

Q: Can I distribute modified QET?

A: Yes, but you must provide source code and license under GPL v2.

Q: Can I make QET proprietary?

A: No. GPL prevents this. Modifications must stay open and free.

Q: Can I sell software based on QET?

A: Yes, but if you distribute it, recipients must get the same freedoms (including source code).

Q: Do my diagrams have to be open source?

A: No. Your work is yours. Only QET software is GPL.

Q: What if I use an old version of QET?

A: Still GPL. All versions are open source.

Q: Will QET always be free?

A: Yes. GPL guarantees this for all versions, forever.

Q: Can I copy/fork QET?

A: Yes. That's exactly what GitHub allows you to do.

Q: Do I need a lawyer to use QET?

A: For personal/educational use: No. For commercial distribution: Maybe consult one.

Getting Legal Help

If you have complex licensing questions:

Software licensing lawyer — For commercial distribution scenarios
FSFE Legal Support — Free Software Foundation Europe offers resources
GitHub Legal Guides — GitHub's open source guides have licensing info
Your lawyer — If you're distributing software commercially

Community questions:

Forum — Ask other users
GitHub Discussions — Technical license questions

Summary

Use Case	Free?	Restrictions?	Must Share Source?
Personal use	✅	None	No
Educational	✅	None	No
Commercial (unmodified)	✅	None	No
Commercial (modified, keep private)	✅	None	No
Distribute unmodified	✅	Must include GPL	Only include file
Distribute modified	✅	Must share source	Yes
Make proprietary	❌	GPL prevents this	N/A