CC0 (Public Domain Dedication)¶
CC0 is not a license—it's a waiver. It places work in the public domain by waiving all copyright and related rights to the maximum extent possible. No attribution required, no restrictions of any kind.
At a Glance¶
| Attribute | Value |
|---|---|
| SPDX Identifier | CC0-1.0 |
| Type | Public domain dedication |
| Free Culture | Yes |
| Attribution Required | No |
| Any Restrictions | No |
What It Allows¶
- Everything
- Commercial use
- Modification
- Distribution
- Private use
- No attribution required
- Use without any conditions
What It Requires¶
- Nothing
What It Prohibits¶
- Nothing (as far as copyright goes)
How CC0 Works¶
CC0 operates in three layers:
1. Public Domain Dedication¶
First, it attempts to waive all copyright:
To the greatest extent permitted by... law, [the person] hereby... dedicates the Work to the public domain
2. Fallback License¶
If waiver isn't legally possible (some jurisdictions don't allow it):
[The person] grants... a royalty-free, non-exclusive, irrevocable... license to use the Work
This is essentially an unlimited permissive license as fallback.
3. Moral Rights Waiver¶
Where possible, it waives "moral rights"—rights to attribution and integrity that exist in some legal systems.
CC0 vs Other Public Domain Tools¶
| Tool | Legal Framework | Best For |
|---|---|---|
| CC0 | Thorough international coverage | Data, research, creative works |
| Unlicense | Simple dedication | Software, quick releases |
| 0BSD | BSD license structure | Organizations wanting license form |
CC0 is the most legally thorough option, drafted with international law in mind.
Why Choose "No Rights"?¶
Maximum Impact¶
CC0 removes all friction. Anyone can use the work for anything without:
- Tracking attribution requirements
- Worrying about license compatibility
- Legal review for commercial use
- Any hesitation at all
Data and Databases¶
For data, CC0 is often ideal because:
- Facts themselves aren't copyrightable (in most jurisdictions)
- Database rights (where they exist) are waived
- Scientific norms provide attribution through citation
- Machine processing doesn't preserve attribution anyway
Building a Commons¶
CC0 contributes to a shared public domain. Works truly belong to everyone.
Attribution Norms vs Requirements¶
CC0 doesn't require attribution, but:
- Academic citation norms still apply
- It's polite to credit sources
- It's honest to acknowledge others' work
- Many fields expect citation regardless of legal requirements
The difference: someone who doesn't cite you isn't breaking the law—just norms.
When to Choose CC0¶
CC0 is appropriate when:
- You want maximum possible reuse
- Attribution isn't important to you
- You're releasing data or databases
- You want to contribute to the public domain
- License compatibility must never be an issue
When to Choose Something Else¶
- You want credit → CC BY
- You want derivatives to stay open → CC BY-SA
- You're releasing software → Unlicense, MIT, or other software license
- You need to reserve commercial rights → CC BY-NC
CC0 for Research Data¶
CC0 is the recommendation of many funders and institutions for research data:
- Science Commons Protocol for Open Data: Recommends CC0
- DataCite: Compatible with CC0
- FAIR Data Principles: CC0 supports FAIRness
Citation practices provide attribution in academic contexts. The legal simplicity of CC0 enables data sharing.
Risks and Considerations¶
You can't take it back¶
Once you dedicate something to the public domain, it's gone. Anyone can do anything with it. Consider carefully.
Patent and trademark¶
CC0 waives copyright, not patents or trademarks. If your work involves patented methods or trademarked names, those remain protected.
Moral rights in some jurisdictions¶
Some countries don't allow waiving moral rights. In those cases, the fallback license applies, but moral rights may persist.
Notable Uses of CC0¶
- Many scientific databases and datasets
- Government data (data.gov, etc.)
- Unsplash photos
- Smithsonian Open Access images
- Cultural heritage digitization projects