Devicehub can generate tags, which are synthetic identifiers that identify a device in an organization. A tag has minimally two fields: the ID and the Registration Number of the organization that generated such ID.

In Devicehub tags are created empty, this is without any device associated, and they are associated or linked when they are assigned to a device. In Devicehub you usually use the AndroidApp to link tags and devices.

The organization that created the tag in the Devicehub (which can be impersonating the organization that generated the ID) is called the tag provider. This is usual when dealing with other organizations devices.

A device can have many tags but a tag can only be linked to one device. As for the actual implementation, you cannot unlink them.

Devicehub users can design, generate and print tags, manually setting an ID and a tag provider. Note though that these virtual tags don’t have to forcefully be printed or have a physical representation (this is not imposed at system level).

Tags are case insensitive and are converted to lower-case in Devicehub.


We recognize a special type of tag, the eReuse.org tags (eTag). These are tags defined by eReuse.org and that can be issued only by tag providers that comply with the eReuse.org requisites.

The eTags are designed to empower device exchange between organizations and identification efficiency. They are built with durable plastic and have a QR code, a NFC chip and a written ID.

These tags live in separate databases from Devicehubs, empowered by the eReuse.org Tag software. By using this software, eReuse.org certified tag providers can create and manage the tags, and send them to Devicehubs of their choice.

The section Use-case with eTags shows the use-case of these eTags.

Tag ID design

The eTag has a fixed schema for its ID: XXX-YYYYYYYYYYYYYY, where:

  • XX is the eReuse.org Tag Provider ID (eTagPId).

  • YYYYYYYYYYYY is the ID of the tag in the provider..

The eTagPid identifies an official eReuse.org Tag provider; this ID is managed by eReuse.org in a public repository. eTagPIds are made of 2 capital letters and numbers.

The ID of the tag in the provider (YYYYYYYYYYYYYY) consists from 5 to 10 capital letters and numbers (registering a maximum of 10^12 tags).

As an example, FO-A4CZ2 is a tag from the FO tag provider and ID A4CZ2.

Creating tags

You need to create a tag before linking it to a device. There are two ways of creating a tag:

  • By performing POST /tags?ids=... and passing a list of tag IDs to create. All users can create tags this method, however they cannot create eTags. Get more info at the endpoint docs.

  • By executing in a terminal flask create-tags <ids> and passing a list of IDs to create. Only an admin is supposed to use this method, which allows them to create eTags. Get more info with flask create-tags --help.

Note that tags cannot have a slash /.

Linking a tag

Linking a tag is joining the tag with the device.

In Devicehub this process is done when performing a Snapshot (POST Snapshot), by setting tag ids in snapshot['device']['tags']. Future implementation will allow setting to the organization to ensure tags are inequivocally correct.

Note that tags must exist in the database prior this.

You can only link once, and consecutive Snapshots that have the same tag will validate that the link is correct –so it is good praxis to try to always provide the tag when performing a Snapshot. Tags help too in finding devices when these don’t generate a HID. Find more in the Snapshot docs.

Getting a device through its tag

When performing GET /tags/<tag-id>/device you will get directly the device of such tag, as long as there are not two tags with the same tag-id. In such case you should use GET /tags/<ngo>/<tag-id>/device to unequivocally get the correct device (feature to develop).

Tags and migrations

Tags travel with the devices they are linked when migrating them. Future implementations can parameterize this.

Photochromic tags

The photochromic Reversible Tag helps the end-user to identify a legitimate device that has correctly refurbished by an eReuse.org authorized refurbisher, without the hassle to read the QR code.

Only eReuse.org authorized organizations can use the Photochromic tags.

Use-case with eTags

We explain the use-case of tagging a device with an eTags, going through the manufacturing of the tags, their distribution and the final linkage between tag and computer.

For this use-case we suppose we want 100 eTags.


  • Tag provider: organization that orders and manages the eTags; it is certified by eReuse.org thus having permission to order the tags.

  • NFC Tag manufacturer.

  • Photochromic tag manufacturer.

  • User: organization that uses the tags.


  • At least one eReuse.org Devicehub. One Devicehub can contain several organizations and inventories, or organizations can have their own copy of Devicehub. Devicehub work distributely over the Internet.

  • One eReuse.org Tag running in a server over the Internet by the tag provider.

Use case

  1. The tag provider enters into the server containing the eReuse.org Tag software and executes the command etag create-tags 100 --csv file.csv, which creates 100 tags in the database and saves their URLs into a spreadsheet CSV file called file.csv.

  2. The tag provider sends the CSV file to the NFC tag manufacturer and orders the 100 tags.

  3. The NFC tag manufacturer creates those tags (NFC plus QR code) and updates the CSV file with the NFC ID of each tag, so each row of the CSV file contains the URL sent by the tag provider and the ID of the NFC tag created by the NFC tag manufacturer.

  4. The Tag provider updates eReuse.org Tag with the ID of the NFC by executing etag update-tags file.csv where file.csv is the file sent by the NFC tag manufacturer.

  5. The Tag provider orders 100 photochromic tags to the Photochromic tag manufacturer. Note that these tags don’t require any special treatment.

  6. The Photochromic tag manufacturer sends back 100 tags.

  7. The Tag provider distributes the eTags (NFC and photochromic) to several organizations, users, both physically by sending them and virtually by executing etag set-tags http://some-devicehub.com 0 100; this marks the tags in eReuse.org Tag as sent to some-devicehub.com and creates the tags in that Devicehub.

  8. The user receives the tags, sticks them in their devices, and scans the NFC or QR codes:

    1. By using the eReuse.org Android App the user can scan the QR code or the NFC of the eTag.

    2. If the user is processing devices with the eReuse.org Workbench, Workbench automatically attaches hardware information like serial numbers, otherwise the user can add that information through the app.

    3. These softwares communicate with the Devicehub of the user and command the Devicehub to link the device with the tag.

    4. The Devicehub of the user links the tag.

    5. The Devicehub creates or updates a virtual entity in Everythng containing the device and the tag.

    6. If Devicehub or Everythng detect that the tag was linked they won’t allow this operation. Devicehub can only detect if the app is linked by looking at its internal database. Everythng, as it contains all device and tag information, validates that the tag is not linked elsewhere.