Open data
Open data licences explained
A licence tells people what they may do with your data. Without one, reuse is legally uncertain, even when the data is easy to download.
Common open licences
| Licence | What it asks of reusers | Notes |
|---|---|---|
| CC0 1.0 | Nothing. A public-domain dedication. | Widely used for scientific and government data where maximum reuse is wanted. |
| CC BY 4.0 | Give attribution. | Covers database rights in version 4.0; common for open government data. |
| CC BY-SA 4.0 | Attribution, and share adaptations under the same licence. | “Share-alike” keeps derivatives open. |
| ODC PDDL | Nothing. Public-domain dedication for databases. | Open Data Commons equivalent of CC0. |
| ODC-By | Give attribution. | Database-specific attribution licence. |
| ODbL | Attribution, share-alike for adapted databases, keep it open. | Used by OpenStreetMap. |
Licences marked “NC” (non-commercial) or “ND” (no derivatives) do not meet the Open Definition. This is general information, not legal advice.
Choosing a licence
Ask two questions: do you need credit (attribution), and do you want derivatives to stay open (share-alike)? If neither, a public-domain dedication such as CC0 or PDDL gives the least friction. Always state the licence next to the data and in its metadata.
Work with ex omnia
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