Data Tags are used to track user properties and events, enabling precise audience targeting and personalized messaging. Tags consist of keys and values that persist for the user's lifetime unless updated or removed. There is no limit to how many tags a OneSignal app can have, but depending on your plan type, there is a limit on how many can be set on each user.

This guide will outline common strategies for using data tags and ways to effectively manage them across your users.

Recommendations

Data Tags are not designed to replace your database. Set tags based on the types of messaging-related use cases you want to achieve including the user data you want to inject into those messages.

Event based tags examples

Event-driven data based on user actions. "keys" should identify the action while "values" should be integers representing "how many times the action was performed" or Unix Timestamps for "when/how long it has been since the action was taken".

Game-Specific

Customers with game apps often target messages to users based on their activity in the game. We recommend storing these as numeric values where possible, in order to use greater than and less than operators.

Account-Related Data

Adding account-related tags is a great way to target messages to groups of users based on properties of their account, such as cohort, or to link user data to your internal database / CRM.

Do not use tags for setting "user IDs" or sending messages to individual users. Instead use the External ID property.

For instance, when tracking upgrade or downgrade events (after purchase or cancelation), you can update these tags to target free vs premium users with different messages.

These events are perfect for matching with Time Operators to track when the upgrade or downgrade event occurred. If you provide subscription plans, you can set up "reminder messages" to let the customer know their plan is about to expire.

User properties

Using a user’s name to personalize notifications is a great way to boost engagement. Just create a key for their name and then use Variable Substitution when crafting your messages.

Do not use tags for setting "user IDs" or sending messages to individual users. Instead use the External ID and/or custom Aliases.

Location & Demographics

Demographic data can be used to create segments and target specific groups of users.

¹ OneSignal SDK collects the user's country.
² OneSignal should not be initialized if the user is under the age of 13.

Best practices

Data Types:

• Data tags only support String values—Arrays, Objects, and Lists are not supported at this time.
• You can store booleans, integers, and floats as Strings (wrapped in quotes). Our backend will parse them for filter operations.

If you need objects, lists, or arrays, for example: "interests" : ["technology", "sports", "entertainment", "finance"] then consider setting the list item as the tag key with a value of "1" or a unix timestamp in seconds of when they set that tag. This allows you to store more data and segment deeper with Tags: Time Operators.

Formatting Best Practices:

• Use lowercase keys unless necessary (e.g., storing a user’s name).
• Avoid spaces and special characters like ~!@#$%^&*'{}|\/'". Use only letters, numbers, underscores (_), or hyphens (-).
• Keep tag values short—fewer characters improve performance. For example, use "1" or "t" instead of "true" and "0" or "f" instead of "false".

Using Numbers Effectively:

• Strings representing numbers (integers or decimals) can be used for segmentation with "greater than" and "less than" operators.
• Use Unix timestamps in seconds to track when a user last performed an action. See Tags: Time Operators for details.

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Do not Set User IDs

Do not use tags for setting "user IDs" or sending messages to individual users. Instead use the External ID and/or custom Aliases.

How add update and remove data tags

There are several ways to add, update, and remove tags as detailed below. Check out your plan details, for the number of custom data tags per user your plan is entitled to set.

• Data Tag SDK Methods: (Recommended) Quickly add, remove, or update tags in almost real-time when users perform actions or events on your site or mobile app. See our Mobile SDK Reference and Web SDK Reference.
• Create user or Update user: Server REST API endpoint for directly updating the tags parameter on single users.
• Journeys: Set tags automatically within a Journey workflow as a user moves through a journey.
• Importing User Attributes or Data Tags: Upload a CSV of user data through the OneSignal Dashboard with the subscription_id or external_id. This enables you to migrate existing data sources into OneSignal.
• Web Category Prompt: If you are integrating OneSignal into your website, then you can add data tags by using our category slide-down prompt. This enables you to capture user interest around what type of messages they'd be interested in.
• User Profile Page: Quickly add and update data tags from the User Profile page UI in the OneSignal dashboard.
• In-App Messages: When you send in-app messages, you can collect data tags based on user engagement through clicks and our click actions. Additionally, data tags can also be used to trigger an in-app.
• Integrations: Depending on the integration partner, there are specific tags that can be set.
  • Hubspot has a "Edit Tags" workflow option to set your own tags.
  • Segment Integration syncs data passed within their SDK as tags.
  • Mixpanel syncs $first_name and $last_name properties as data tags first_name and last_name.

Importing Data Tags

Data tags can be added and updated for your users by utilizing our CSV importer, our Update User API endpoint, or by manually updating them in the subscription details screen of the dashboard. See our Import User Tags guide for more details.

Export Users Over Tag Limit

Navigate to Audience > Subscriptions > Arrow next to Export.

This is the ability to export all subscriptions with N tags. Note. N will change depending on your plan type and is the plan-specific data tag limit. This ensures you can always remove tags for subscriptions above your current plan entitlement.

Export from Dashboard

Once you have selected Export you'll shortly receive an email to your account email address, to begin the download. We provide this via email, as you may export thousands or even millions of subscriptions.
The CSV will have two formats depending on whether you are exporting all subscriptions or the subscriptions with data tags above the plan allowance:

1. Exporting All Users: This will include all metadata and columns shown in your dashboard. Data Tags export as a JSON blob.
2. Exporting Users with 10 Tags: This provides a limited number of columns including both subscription_id and external_id (if applicable), along with data tags, where each data tag key is a column, and each row represents a value that corresponds to that id.

Editing and Deleting Your Data Tags

The subscription data comes in a CSV format, which enables you to open in Excel, Google Sheets, or Apple's Numbers. Upon opening, you should now be able to effectively edit, or delete any tags as needed.

To delete a tag, include the tag name to be deleted as a column header, but leave an empty cell for the corresponding value. Under Advance Settings ensure that you click the checkbox for "Delete existing data tag values when the uploaded value is null" when importing your CSV to remove tags with null values for your users.

When saving the altered CSV, make sure that you save it as a CSV. Some editors will save it in their default format, for example, *.xslx. Our importer does not accept any formats other than CSV.

Uploading your data tags

Now your data tags have been edited and deleted, you can now upload your subscribers back into OneSignal. See our Data Tag Import guide for details on how to upload your new file.

FAQ

What if I don't have the external_id set?

OneSignal intentionally does not automatically collect Personally Identifiable Information for data privacy reasons. If you have not enriched OneSignal with the external_id property or Data Tags, it can be difficult to map the user record in OneSignal with your database user record. Based on Data Collected by the OneSignal SDK like IP Address and Device (along with any data tags you may have set), you could try Exporting User Data from OneSignal and match any data within your database to map users to a CSV and upload using the onesignal_id and adding the external_id and other tag columns.

For proper user matching, we highly recommend adding the external_id through our client-side SDK. See Users for more details.

How many tags can I set?

Check your plan limits, for the number of custom data tags per user. If you need more, contact our sales team to discuss more options.

Where can I check how many tags my users have?

Navigate to Audience > Users page "Tags" column or see Exporting User Data.

How do I know if I’m using more tags than my current plan allows?

You can export the specific users over the plan limit within the dashboard Audience > Users > Export. Details in Bulk Updating User Attributes or Data Tags.

How do I reduce the number of data tags my app is using?

There are several options including API updates to uploading a CSV. See Tags: Tracking User Events and Attributes for a list of all options.

What happens to my data tags if am over the plan entitlement?

Your application will continue to have the data tags set per user. When adding or updating tags, you won't be able to make changes to users over your plan limits. This means if a user is at or over their tag limit, you will first need to delete the unwanted tags, then make another request to add or update the desired tags.

For example, if your account tag limit is 20 custom tags per user, then each user can only have 20 unique tag "keys" set at once.

If a user has 0 tags:

• Any request to set 1-20 tag keys, will succeed.
• Any request to set 21+ tag keys, will fail, no tags will be set.

If a user has 19 tags:

• A request to set 1 new tag key will succeed.
• A request to set 2+ new tag keys will fail, no new tags will be set.
• A request to update 1-19 of the currently set tag values and set 1 new tag will succeed.
• A request to update 1-19 of the currently set tag values and set 2+ new tag will fail. You need to make 2 requests. 1st to delete the unwanted tag keys, 2nd to set the new tag keys.

Why are data tags not showing on my device?

There are a few reasons why tags may not be set listed below.

Offline or Unstable Network Connection

The most common reason for tags not showing on a device is due to unstable or no network connection where the request to update the tags does not make it to OneSignal.

Android Mobile SDKs will cache data tags and will retry adding the tag upon detecting a stable internet connection.

iOS Mobile SDKs provides a callback for you to handle this case.

Web SDK, the user must be subscribed before the tag is added to the device record. Once the user registers, the tags will automatically be sent to our server as long as the page session is the same (the user has not navigated to another page).

End of Page Session

Web SDK - If the person leaves the page before the tags are set, they will not get the tags.

Clearing Browser Cache

When web subscribers clear their browser data/cookies/cache it destroys the push records for al sites that the user is subscribed under. OneSignal provides a feature to automatically resubscribe the user upon returning to the site with our SDK, but this will not add the tags back unless some additional steps are taken. See What happens when I clear browser cookies? for more details.