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GET
Evaluate Experiments

Authorizations

Authorization
string
header
required

An Account API key, an App API key, an account access token, an account-scoped user token, or a user OAuth token. Prepend the key or token with Bearer, for example Bearer ***************************. See Auth & API keys for how to get each one.

Headers

Api-Version-Date
string

Pins the request to a dated API version.

Example:

"2026-10-15-1"

Query Parameters

subject
object

Bucketing subject: the user, account, or anonymous ID the experiment's bucket_by assigns on. Only the identity matching bucket_by is used; when it is missing, evaluating a single flag fails and a batch omits that experiment. Subjects outside every treatment range receive control. subject[account_id] also enables account-level targeting rules. Experiment ownership comes from the top-level account_id.

Restricts batch evaluation to this related resource; omitted batches contain only unbound experiments.

flag_key
string

Flag or experiment to evaluate — the flag_key handle or the expt_ id. Omit to return all flags the caller qualifies for.

account_id
string

Owning account ID. Required when evaluating by flag_key or in a batch; optional for an expt_ ID.

log_exposure
boolean

Set false to read an assignment without recording an exposure, such as when a client caches assignments up front and records the exposure when the arm is rendered. Omitted records the exposure.

Response

200 - application/json

single flag evaluated

enabled
boolean
required

Whether the subject receives a treatment or enabled feature flag.

Example:

true

variant
string | null
required

Treatment name, control, or null for an inactive flag or excluded subject.

Example:

"treatment"

configuration_revision
integer
experiment_id
string

Unique experiment ID, included for account experiments.

flag_key
string

Present when evaluating a single experiment.

Example:

"checkout_redesign"