Complete explanation of the ODbL license of OpenStreetMap and implications

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OpenStreetMap is often associated with a collaborative map, but the ODbL license governing its data deserves a closer look. Between sharing obligations, compatibility with other datasets, and best practices for your projects, this license shapes how you can reuse and enrich free cartography. Let’s dive into its world to clear up any ambiguity.

Origin and Purpose of the ODbL License

The Open Data Commons Open Database License (ODbL) was created in 2009, born from a shared desire to guarantee free access to geographic databases while protecting collaborative work. One might think it is simply a variant of a Creative Commons license, but the ODbL goes further by specifically targeting databases. Essentially, it allows copying, modification, and redistribution, provided certain key clauses are respected.

Main Obligations Imposed by the ODbL

While the license is permissive, it imposes a strict framework to avoid any misuse:

• Attribution: every publication must mention OpenStreetMap and its contributors.
• Share-Alike: any derived version must be distributed under the same license.
• Preservation of access rights: modified data remains open.

The Share-Alike Clause

This clause, often called “Share-Alike,” ensures that improvements made to the database also remain free. Imagine a developer refining the bike path routes: they cannot lock access to it; they must republish their adjustments under ODbL. This principle protects the community and ensures the ecosystem’s sustainability.

The Attribution and Credit Clause

It is not enough to simply mention “OpenStreetMap data.” The credit must be explicit, for example, “Cartographic data © OpenStreetMap contributors, under ODbL license.” In practice, a footer on a mobile app or a caption on a web map suffices, provided the information is clearly visible.

Compatibility and interactions with other licenses

A major challenge is combining ODbL data with layers from other licenses. For example, importing a set of historical landmarks published under CC-BY into an ODbL database becomes tricky: the Share-Alike clause then applies to the whole. This is called the “virality” of the license, which extends its obligations to incorporated third-party data.

Furthermore, if you display a map of the French departments as an overlay, check that these boundaries do not come from an incompatible source. Otherwise, you risk breaking the legal harmony of OpenStreetMap.

Integrating ODbL into your mapping projects

Good practices are not limited to a simple copy-paste of the license. Upstream, precisely document which parts of the database you use: polygon extracts, geotags, topology… This traceability facilitates maintenance and updates.

Technically, tools like Osmosis or the Overpass API help you extract precise areas without taking the entire dataset. Then, adapt your project license to explicitly include ODbL in your terms of use.

Concrete examples and compliance with obligations

Several companies and associations have successfully integrated ODbL. One of them created an urban transport tracking application, publishing its own road flow data under ODbL on GitHub. Another example, a cyclists’ collective enriched the OpenStreetMap database with new green routes before republishing the whole under the same license.

Sanctions and risks in case of non-compliance

Ignoring obligations not only exposes you to a claim from the OpenStreetMap Foundation: a French court may consider license violation as an act of counterfeiting. Requests for removal, injunctions, or even damages are possible if attribution or Share-Alike compliance is not ensured.

Tips to maintain compliance

• Provide a detailed README file with your data.
• Automate the generation of legal notices in your exports.
• Monitor updates: the database constantly evolves, remember to regularly check your integration.
• Train your team on ODbL principles to avoid mistakes.

FAQ

What is the OpenStreetMap ODbL license?

It is a license designed for databases, allowing copying, modification, and redistribution of geographic data while imposing attribution and share-alike requirements.

What are the main obligations imposed by ODbL?

You must mention OpenStreetMap and its contributors, share your derivatives under ODbL, and maintain free access to the modified data.

Can I combine ODbL with other licenses?

Yes, but be careful: the Share-Alike nature of ODbL can extend its obligations to included third-party data, risking a legal conflict if the external license is more restrictive.

How to correctly cite OpenStreetMap in my projects?

An explicit mention, for example “Data © OpenStreetMap contributors,” placed in a caption, footer, or README file, is sufficient to satisfy the attribution clause.

What are the consequences of non-compliance with the license?

Beyond a formal notice, you risk counterfeiting lawsuits and immediate removal requests of your applications or data servers.

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