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Identify API

Use the Identify API to set the User ID for a particular Device ID or update user properties of a particular user without sending an event. You can change Amplitude default user properties and custom user properties that you have defined.

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Authorization

This API doesn't use authorization, but uses your API key. How you pass it depends on whether you're passing data in the URL or the body of your request.

  • For URL parameters: pass the API key in the URL of the request like https://api2.amplitude.com/endpoint?api_key={{api-key}} or in the body
  • For body parameters: pass the API key in the body of the request like this: 
    curl --location --request POST 'https://api2.amplitude.com/identify' --header 'Content-Type: application/x-www-form-urlencoded' --data-urlencode 'api_key=<API-KEY>'

See Find your Amplitude Project API Credentials for help locating your credentials.

Endpoints

Region Endpoint
Standard Server https://api2.amplitude.com/identify
EU Residency Server https://api.eu.amplitude.com/identify

Considerations

  • You can update user properties that you haven't tracked yet. However, property values don't apply or appear in the platform until the user's next event. Learn more about applying user properties.
  • Updates aren't retroactive, and only apply to future events.
  • Amplitude throttles requests for device_ids or user_ids that exceed a certain threshold of events per second. When Amplitude throttles a request, the request returns a HTTP status code 429. Pause sending events for any devices in that request for 15 seconds before retrying. Continue retrying until you no longer receive status code 429. If the same user_id is sending events from multiple devices simultaneously, then all the devices would be throttled. All throttling and status code guidance from Amplitude's HTTP V2 API applies to the Identify API.
  • Amplitude compares dates as strings, so Amplitude recommends that you use the ISO 8601 format (YYYY-MM-DDTHH:mm:ss). This lets you perform date comparisons in the web app. For example, '2016-01-31' > '2016-01-01'). This also applies to datetime values like '2017-08-07T10:09:08' > '2017-08-07T01:07:00'.
  • Updates don't appear Redshift because they don't count as events.
  • Because these calls aren't counted as events, this API has no effect on "active user" or "new user" definitions.
  • Because these calls aren't counted as events, Identify API calls don't add to your monthly event count in Amplitude.
  • If you change the user_id field from an existing value, then Amplitude creates a new user. Amplitude doesn't create a new Amplitude user if the current value of user_id is null.

Example request

curl --location --request POST 'https://api2.amplitude.com/identify' \
--header 'Content-Type: application/x-www-form-urlencoded' \
--data-urlencode 'api_key=<API-KEY>' \
--data-urlencode 'identification=[{"user_id":"value", "user_properties":{"propertyNameToUpdate":"newValue"}}]'

Required parameters

You can send these parameters as query parameter in a GET request. In a POST request, send them as body parameters. The body must be form-data or x-www-form-urlencoded.

Name
 Description
api_key Your project API key.
identification Either a single JSON identification object or an array of JSON objects, each of which represents one identification.

Identification parameter keys

Name
 Type Description
user_id Required unless device_id is present. String. A UUID (unique user ID) specified by you. If you send a request with a user_id that's not in the Amplitude system yet, then the user tied to the user_id isn't marked new until their first event.
device_id Required unless user_id is present. String. A device specific identifier, such as the Identifier for Vendor (IDFV) on iOS.
user_properties Optional. Dictionary. A dictionary of key-value pairs that represent data tied to the user. Each distinct value appears as a user segment on the Amplitude dashboard. Object depth may not exceed 40 layers. You can store property values in an array and date values are transformed into string values.
groups Optional. Dictionary. This feature is only available to Enterprise customers who have purchased the Accounts add-on. A dictionary of key-value pairs that represent groups of users. Setting groups allows you to use account-level reporting. You can track up to 5 unique group types and 10 total groups.
app_version Optional. String. The version of the app the user is on.
platform1 Optional. String. The platform that's sending the data.
os_name1 Optional. String. The mobile operating system or browser the user is on.
os_version1 Optional. String. The version of the mobile operating system or browser the user is on.
device_brand1 Optional. String. The device brand the user is on.
device_manufacturer1 Optional. String. The device manufacturer of the device that the user is on.
device_model1 Optional. String. The device model the user is on.
carrier1 Optional. String. The carrier the user has.
country2 Optional. String. The country that the user is in.
region2 Optional. String. The geographical region the user is in.
city2 Optional. String. The city the user is in.
dma2 Optional. String. The Designated Market Area of the user.
language Optional. String. The language the user has set.
paying Optional. String. Whether the user is paying.
start_version Optional. String. The version of the app the user was on first.

user_properties supported operations

The user_properties field supports these operations:

Name
 Description
$set Sets the value of a property.
$setOnce Set the value only if the value hasn't already been set.
$add Adds a numeric value to a numeric property.
$append and $prepend Appends and prepends the value to a user property array.
$unset Removes a property
$preInsert Adds the specified values to the beginning of the list of properties for the user property if the values don't already exist in the list. Can give a single value or an array of values. If a list is sent, the order of the list is maintained.
$postInsert Adds the specified values to the end of the list of properties for the user property if the values don't already exist in the list. Can give a single value or an array of values. If a list is sent, the order of the list is maintained.
$remove Removes all instances of the values specified from the list. Can give a single value or an array of values. These should be keys in the dictionary where the values are the corresponding properties that you want to operate on.

Example

You can't mix user property operations with actual top-level user properties. Instead, include them inside the $set operation. If you are using one of these operators then this dictionary can contain only user property operations and you can't combine it with the above format. For example. you can't do {"$append":{"interests":"Music"}, "subscription type":"paid"} in the same request.

Instead, do this: {"$set": {"cohort": "Test A"}, "$setOnce": {"startDate": "2015-10-01"}, "$add": {"friendCount": 3}, "$append": {"interests": "Music"}, "$prepend":{"sports": "Tennis"}, "$unset": {"oldProperty": "-"}}

Status codes

Code Message
200 Success
400 Bad Request. If you get a missing_event message, it means the identification parameter is missing or incorrectly formatted.
414 You might be using GET, which has a URL character limit. Use POST instead of GET so the data isn't passed in the URL.
429 Amplitude throttles requests for device_ids or user_ids that exceed a certain threshold of events per second, and returns a 429 code.

  1. You must update the fields (platform, os_name, os_version, device_brand, device_manufacturer, device_model, and carrier) together. Setting any of these fields resets all the other property values to null if aren't explicitly set on the same identify call. All property values otherwise persist to later events if the values aren't changed to a different string or if all values are passed as null. Amplitude tries to use device_brand, device_manufacturer, and device_model to map the corresponding device type. ↩↩↩↩↩↩↩

  2. You must update the fields (country, region, city, DMA) together. Setting any of these fields automatically resets the others if they aren't also explicitly set on the same identify call. ↩↩↩↩

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