SDK Fetch - Read

Endpoint

/o/sdk

Overview

Processes SDK fetch requests for installed feature methods.

Authentication

• SDK app key: app_key
• SDK device id: device_id

Permissions

• No dashboard-user permission model. Access is controlled by valid app_key and SDK request validation logic.

Request Parameters

Parameter	Type	Required	Description
app_key	String	Yes	Application key.
device_id	String	Yes	Device identifier. Used with app key to derive app-user hash.
method	String	Usually	Feature-specific method name handled by installed /o/sdk listeners.
metrics	Object/JSON String	No	Optional metrics object. String values are parsed when possible.
checksum	String	Conditionally	Required when app checksum salt is configured and SHA-1 checksum mode is used.
checksum256	String	Conditionally	Required when app checksum salt is configured and SHA-256 checksum mode is used.
ip_address	String	No	Optional explicit IP used instead of request IP.
old_device_id	String	No	Optional old device id for merge flows in applicable handlers.

Response

Success Response

Example object-root success (method-dependent):

{
  "segments": {
    "country": "US"
  },
  "configs": {
    "welcome": true
  }
}

Example wrapped success (method-dependent):

{
  "result": "Success"
}

Response Fields

Field	Type	Description
(root)	Any JSON type	Method-specific payload returned by the feature handling the request.

Error Responses

Status Code: 400 Bad Request

{
  "result": "Missing parameter \"app_key\" or \"device_id\""
}

Status Code: 400 Bad Request

{
  "result": "App does not exist"
}

Status Code: 400 Bad Request

{
  "result": "Invalid method"
}

Status Code: 200 OK

{
  "result": "Request does not match checksum"
}

Status Code: 200 OK

{
  "result": "Request does not have checksum"
}

Status Code: 200 OK

{
  "result": "Ignoring device_id"
}

Behavior/Processing

Behavior Modes

Mode	Trigger	Processing Path	Response Shape
Method handled	Installed feature handles requested SDK method	Returns method-specific payload.	Any JSON payload shape.
Unhandled method	No feature handles method	Returns invalid-method error.	Wrapped error string.
Checksum gate fail	App has checksum salt and checksum is missing/invalid	Request cancelled before method handling.	Wrapped informational error string with status 200.
Ignored device id	device_id is zero-IDFA value	Request ignored.	Wrapped informational string with status 200.

Database Collections

Collection	Used for	Data touched by this endpoint
countly.apps	App validation and settings source	Reads app record by app_key.
countly.app_users{appId}	App-user context source	Reads current app-user document by derived _id.

---

Examples

Example 1: SDK fetch request

/o/sdk?app_key=YOUR_APP_KEY&device_id=DEVICE_ID&method=ab_fetch_experiments

Example 2: Missing required params

/o/sdk?method=ab_fetch_experiments

{
  "result": "Missing parameter \"app_key\" or \"device_id\""
}

---

Operational Considerations

• Response contracts are owned by feature handlers, not by this core entrypoint.
• Monitoring should include both 400 Invalid method rates and checksum-gate 200 informational responses.

Limitations

• There is no single fixed success schema for this endpoint.

Related Endpoints

• SDK Ingestion

Last Updated

2026-02-17