Attributes (Feature Flags)

Feature Flag projects manage user attributes from the Audiences > Attributes tab. Attributes are the user properties available for audience targeting, and come in two categories: auto-detected attributes that the SDK captures automatically, and custom attributes that your application passes during flag evaluation.

Auto-detected attributes

When you create a Feature Flag project, 11 built-in attributes are registered automatically. These are properties the SDK detects from the user's environment without any code from your side.

All SDK attributes

These attributes are available in both client-side and server-side SDKs:

• browser — Browser name (Chrome, Firefox, Safari, etc.)
• browserVersion — Browser version string
• os — Operating system (Windows, macOS, Linux, iOS, Android)
• osVersion — OS version string
• deviceType — Device category: desktop, mobile, or tablet
• country — Two-letter country code from IP geolocation

For server-side SDKs, pass userAgent and ip in the evaluation context to enable detection:

1client.evaluateFlag('flag-key', {
2  userAgent: req.headers['user-agent'],
3  ip: req.ip,
4})

Client-only attributes

These attributes are detected from browser APIs and are only available in client-side SDKs (@avsbhq/react):

• language — Browser language code (en-US, fr, de)
• timezone — IANA timezone (America/New_York)
• screenWidth — Screen width in pixels
• screenHeight — Screen height in pixels
• darkMode — Whether the user prefers dark color scheme

Custom attributes

Custom attributes represent properties from your application — user identity, subscription plan, feature entitlements, team membership, or any other data you want to target by.

Registering a custom attribute

1. Go to Audiences > Attributes
2. Click "Add Attribute"
3. Fill in the key (alphanumeric with underscores, e.g. userId), display name, type (String, Number, Boolean, or JSON), and optional description
4. For String attributes, you can add suggested values (e.g. free, pro, enterprise) that appear as dropdown options in the audience builder

Creating attributes inline from the audience builder

You can also create a new attribute without leaving the audience you are building. When you add a Custom Attribute condition, the attribute picker has a + New attribute affordance at the bottom of the dropdown. Click it to open a small form, register the attribute, and have it auto-selected for the condition you were editing — no round-trip to the Attributes tab.

Passing custom attributes in your code

1client.evaluateFlag('checkout-redesign', {
2  userId: user.id,
3  plan: user.subscription.plan,
4  companySize: user.company.employeeCount,
5})

Attribute types and operators

Each attribute type supports different comparison operators in audience conditions:

• String — equals, does not equal, contains, starts with, ends with, regex, in list, not in list, exists, does not exist
• Number — equals, does not equal, greater than, less than, greater than or equal, less than or equal, exists, does not exist
• Boolean — equals, does not equal, exists, does not exist
• JSON — contains, does not contain, exists, does not exist

Deleting attributes

Custom attributes can be deleted from Audiences > Attributes. Built-in auto-detected attributes cannot be deleted.

If a custom attribute is used in any audience condition, deletion is blocked. Remove the attribute from all audience conditions first, then delete it.