The software you write and the software you borrow

A developer builds a booking app. She writes the scheduling logic, uses a library for dates, adds a payment integration, and borrows an icon set. To the customer it is one product. To the law it is several pieces, each with its own owner and its own permission. Sort them out piece by piece.

Know what your own code gives you

U.S. copyright protects the expression in a computer program: the code you wrote. It does not protect the program's algorithms, formatting, functions, logic or system design 1. Copyright stops others from copying your code, not from building the same features.

Then check who owns that code. Code an employee writes as part of their regular duties is a work made for hire, and the employer is its author and owner. Code from a freelancer is a work made for hire only if it falls into one of nine listed categories and both sides signed a written agreement calling it one; computer programs are not on that list 7. Otherwise the freelancer owns what they wrote until they transfer it, and a transfer of copyright is valid only in a writing signed by the owner 8. Get that signed assignment before you pay the final invoice. Who owns work made by employees and freelancers walks through the paperwork.

Open source gives permission with conditions

Open source does not mean public domain, and it does not just mean you can see the code. A license meets the Open Source Definition only if it allows free redistribution, includes source code and allows modifications and derived works, among other criteria 2. Those permissions come from the license, so find it first.

Code in a public repository with no license is not open source. Without a license, default copyright law applies: nobody else may reproduce, distribute or create derivative works from it 9. Look for a LICENSE file in the repository root; if there is none, ask the author for a license or do not use the code.

Permissive licenses still have conditions:

• MIT. Keep the copyright notice and the permission notice in all copies or substantial portions of the software. The software comes "as is", with no warranty 3.
• Apache 2.0. Give recipients a copy of the license. Mark files you changed with prominent notices that you changed them. Keep the copyright, patent, trademark and attribution notices from the source. If the project has a NOTICE file, pass on its attribution notices. Each contributor grants you a patent license, and that license ends if you sue claiming the work infringes your patent 4.

For the booking app, that means a short record for every dependency: name, version, license, and where its notices are kept in the product. An update can bring in new code or a new license, so update the record with every release.

Copyleft depends on what you do with the software

The GNU GPL version 3 lets you make, run and change covered software for yourself with no conditions while your license stays in force 5. The conditions start when you convey it: pass copies to others. Letting users interact with the program over a network, with no copy transferred, is not conveying 5. When you do convey it:

1. Ship object code only together with its Corresponding Source, using one of the methods the license lists, such as offering the source from the same place as the download 5.
2. License a modified version as a whole under the GPL to anyone who receives a copy 5.

Separate, independent programs that only sit next to GPL code on the same storage or distribution medium form an aggregate, and the GPL does not apply to those other programs 5. Code combined with GPL code into one larger program is a different case.

If a copyright holder tells you that you broke the GPL, act fast: the first time you get notice from that holder, curing the violation within 30 days of receiving the notice restores your license 5.

The GNU AGPL version 3 closes the hosting gap. If you modify AGPL software and users interact with your version remotely over a network, you must prominently offer those users the Corresponding Source of your version from a network server at no charge 6. So "we only host it, we never ship it" works for GPL code you do not distribute but not for modified AGPL code.

Before you release a product that combines GPL or AGPL code with code you keep closed, have a software-licensing attorney review how the pieces are combined and what you must publish.

Code is not the only material in the product

Fonts, icons, graphics, documentation, training data and sample content each come with their own license. A repository's license can cover only part of what is in it, so read the license for each asset. Check that a font license covers embedding the font files in an app, not only using the font on a website.

If you deliver software to a client, list which parts are your custom code and which are third-party components under their own licenses. Promise the client ownership only of the code you can transfer. The client still gets a product they can maintain, and future developers know which parts they may change, redistribute or replace.

Register the code you own

The Copyright Office encourages you to apply before you publish and to apply online through its electronic registration system 1:

1. File one application per version. Each new version with new copyrightable code is a separate work, though unpublished versions can sometimes be grouped 1.
2. Claim only your new code. A registration does not cover previously published or registered code, public-domain code, or code owned by someone else, such as your open-source dependencies. Fill in the "Limitation of Claim" field to identify what you are claiming 1.
3. Deposit source code. Without trade secrets, send the first 25 and last 25 pages. With trade secrets, say so in writing and choose a redacted option, such as the first and last 10 pages unredacted, or the first and last 25 pages with less than half blocked out 1.
4. Pay the filing fee. Check the current amount on the Copyright Office fee page before you file 10.

Make the next release easier

Keep a dependency record and a folder of license texts and notices with every release. When you plan a mobile app, a customer installation or an acquisition, you then start from facts, not from a search through old commits. Open collaboration is why software moves fast. Following the licenses honors that work and hands the next developer a product they can keep building.