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Initialize SDK

This topic describes how to initialize the Optimizely Go SDK in your application.

To initialize the OptimizelyClient you will need either the SDK key or hard-coded JSON datafile.

Basic initialization with SDK Key

import optly ""

// Instantiates a client that syncs the datafile in the background
optlyClient, er := optly.Client("SDK_KEY_HERE")

Static client instance

If you do not want the client to periodically sync the datafile in the background, you can instantiate a static client. This is useful for using the SDK in short-lived environments, such as Lambda functions. You can use the OptimizelyFactory for these more advanced use cases:

import ""

optimizelyFactory := &client.OptimizelyFactory{
          Datafile: []byte("DATAFILE_JSON_STRING_HERE"),

// Instantiate a static client (no datafile polling)
staticOptlyClient, err := optimizelyFactory.StaticClient()

If you want the SDK to initialize and perform just a one-time remote datafile fetch you can pass in the SDK key instead and instantiate a static client:

import ""

optimizelyFactory := &client.OptimizelyFactory{
          SDKKey: "[SDK_KEY_HERE]",

// Instantiate a static client that will pull down the datafile one time
staticOptlyClient, err := optimizelyFactory.StaticClient()

Advanced configuration

You can further customize the top-level components of the SDKs: Event Processor, Config Manager, and Decision Service using the OptimizelyFactory:

import (

optimizelyFactory := &client.OptimizelyFactory{
          SDKKey: "[SDK_KEY_HERE]",

datafilePollingInteval := 2 * time.Second
eventBatchSize := 20
eventQueueSize := 1500
eventFlushInterval := 10 * time.Second

// Instantiate a client with custom configuration
optimizelyClient, _ := optimizelyFactory.Client(
		client.WithPollingConfigManager(datafilePollingInterval, nil),

For more details on configuring the event batching please see Event Batching.

Use authenticated datafile in secure environment

You can fetch the Optimizely datafile from an authenticated endpoint using a server-side (only) Optimizely SDK. To use an authenticated datafile, download your Optimizely environment's access token from the Optimizely app at Settings>Environments. Select your secure environment, and copy the Datafile access token. The example below shows how to initialize the Optimizely client using an access token and sdk_key, enabling the client to fetch the authenticated datafile and complete initialization.

// fetch the datafile from an authenticated endpoint
sdkKey := `<YOUR_SKD_KEY>`
factory := client.OptimizelyFactory{SDKKey: sdkKey}
optimizelyClient, err := factory.Client(client.WithDatafileAccessToken(accessToken))