---
title: Migrating from Legacy Go SDK to Go Core
description: Learn how to migrate from the legacy Go Server SDK to the new Go Core SDK with improved performance and new features
product: general
token_estimate: 1943
---
# Migrating from Legacy Go SDK to Go Core

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This guide covers migrating from the legacy Go Server SDK to the Go Core SDK. The Go Core SDK offers significant performance improvements and new features, built on a shared Rust core library.

## Why migrate

- **Performance**: Go Core achieves faster evaluation times and lower CPU consumption, making it more efficient than the legacy SDK.
- **New Features**: Access to Parameter Stores.
- **Future Support**: All new features and improvements are only available in Go Core.
- **Maintenance**: The legacy Go SDK is in maintenance mode and only receives critical bug fixes.

## Installation differences

### Legacy Go SDK

#### CLI

```bash
go get github.com/statsig-io/go-sdk
```

#### go.mod

```go
require (
  github.com/statsig-io/go-sdk v1.26.0
)
```

### Go Core SDK

Go Core requires the new package and additional setup. Install the latest version of the SDK:

#### Latest Version

```bash
go get github.com/statsig-io/statsig-server-core/statsig-go@latest
```

#### Specific Version

```bash
go get github.com/statsig-io/statsig-server-core/statsig-go@v0.7.2
```

#### go.mod

```go
require (
  github.com/statsig-io/statsig-server-core/statsig-go v0.7.2
)
```

Go to the [Releases tab in GitHub](https://github.com/statsig-io/statsig-server-core/releases) for the latest versions.

Run the following commands to install the necessary binaries and set environment variables:

```bash
go install github.com/statsig-io/statsig-server-core/statsig-go/cmd/post-install@latest
post-install
```

Follow the prompts to set the environment variables using the `statsig.env` or `statsig.env.ps1` file generated during the post-install script.

#### macOS

```bash
source /Users/Your-User-Name/.statsig_env
```

#### Windows (PowerShell)

```powershell
. "C:\Users\Your-User-Name\.statsig_env.ps1"
```

Add the variables to your `.bashrc`, `.zshrc`, or `.ps1` file to load them automatically.

> **Note:**
>
> You may need to install gcc on your system to run the SDK on Windows. Refer to [FAQ](https://docs.statsig.com/server-core/go-core#faq) for more information.

Refer to [FAQ](https://docs.statsig.com/server-core/go-core#faq) if you encounter any issues with installation.

## API differences

### Key package and import changes

| Feature | Legacy Go SDK | Go Core SDK |
| --- | --- | --- |
| Import | `github.com/statsig-io/go-sdk` | `github.com/statsig-io/statsig-server-core/statsig-go/src` |
| Main Package | `statsig` | `statsig` |
| Initialization | Static `statsig.Initialize()` | Instance-based `statsig.Initialize()` |
| Options | `&Options{}` | `statsig.NewStatsigOptionsBuilder().With*().Build()` |
| User Creation | `statsig.User{}` | `statsig.NewStatsigUserBuilder().With*().Build()` |

### Initialization

#### Legacy Go SDK

```go
import (
  statsig "github.com/statsig-io/go-sdk"
)

statsig.Initialize("server-secret-key")

// Or, if you want to initialize with certain options
statsig.InitializeWithOptions("server-secret-key", &Options{Environment: Environment{Tier: "staging"}})
```

#### Go Core SDK

```go
import (
    statsig "github.com/statsig-io/statsig-server-core/statsig-go/src"
)

// Create options (all optional)
options := statsig.NewStatsigOptionsBuilder().
    WithOutputLogLevel("DEBUG").
    WithSpecsSyncIntervalMs(10000).
    WithEventLoggingFlushIntervalMs(10000).
    Build()

// Create and initialize the SDK
s, err := statsig.NewStatsig("server-secret-key", options)
if err != nil {
    // Handle error
}

// Initialize the SDK
s.Initialize()

// Or if you want to initialize with details
details, err := s.InitializeWithDetails()
if err != nil {
    // Handle error
}
```

### Checking gates

#### Legacy Go SDK

```go
import (
  statsig "github.com/statsig-io/go-sdk"
)

user := statsig.User{
  UserID: "123",
  Email: "test@example.com",
}

// Check if a gate is enabled
enabled := statsig.CheckGate(user, "my_gate")
```

#### Go Core SDK

```go
import (
    statsig "github.com/statsig-io/statsig-server-core/statsig-go/src"
)

s, err := statsig.NewStatsig("server-secret-key", statsig.StatsigOptions{})

user := statsig.NewStatsigUserBuilder().
    WithUserID("123").
    WithEmail("test@example.com").
    Build()

// Check if a gate is enabled
enabled := s.CheckGate(user, "my_gate")
```

### Getting dynamic configs

#### Legacy Go SDK

```go
import (
  statsig "github.com/statsig-io/go-sdk"
)

user := statsig.User{
  UserID: "123",
  Email: "test@example.com",
}

// Get a dynamic config
config := statsig.GetConfig(user, "my_config")
value := config.Get("key", "default_value")
```

#### Go Core SDK

```go
import (
    statsig "github.com/statsig-io/statsig-server-core/statsig-go/src"
)

s, err := statsig.NewStatsig("server-secret-key", statsig.StatsigOptions{})

user := statsig.NewStatsigUserBuilder().
    WithUserID("123").
    WithEmail("test@example.com").
    Build()

// Get a dynamic config
config := s.GetDynamicConfig(user, "my_config")
```

### Getting experiments

#### Legacy Go SDK

```go
import (
  statsig "github.com/statsig-io/go-sdk"
)

user := statsig.User{
  UserID: "123",
  Email: "test@example.com",
}

// Get an experiment
experiment := statsig.GetExperiment(user, "my_experiment")
```

#### Go Core SDK

```go
import (
    statsig "github.com/statsig-io/statsig-server-core/statsig-go/src"
)

s, err := statsig.NewStatsig("server-secret-key", statsig.StatsigOptions{})

user := statsig.NewStatsigUserBuilder().
    WithUserID("123").
    WithEmail("test@example.com").
    Build()

// Get an experiment
experiment := s.GetExperiment(user, "my_experiment")
```

### Logging events

#### Legacy Go SDK

```go
import (
  statsig "github.com/statsig-io/go-sdk"
)

user := statsig.User{
  UserID: "123",
  Email: "test@example.com",
}

// Log an event
statsig.LogEvent(Event{
		User: user,
		EventName: "add_to_cart",
                Value: "SKU_12345",
		Metadata: map[string]string{"price": "9.99","item_name": "diet_coke_48_pack"},
	})
```

#### Go Core SDK

```go
import (
    statsig "github.com/statsig-io/statsig-server-core/statsig-go/src"
)

s, err := statsig.NewStatsig("server-secret-key", statsig.StatsigOptions{})

user := statsig.NewStatsigUserBuilder().
    WithUserID("123").
    WithEmail("test@example.com").
    Build()

event := map[string]interface{}{
		"name":  "sample event",
		"value": "event",
		"metadata": map[string]string{
			"val_1": "log val 1",
		},
	}

// Log an event
s.LogEvent(*user, event)
```

## Key migration steps

1. **Update Dependencies**: Change from `github.com/statsig-io/go-sdk` to `github.com/statsig-io/statsig-server-core/statsig-go/src`
2. **Run Post-Install**: Execute the post-install script to set up environment variables and download the latest version of the Rust core library.
3. **Update Initialization**:

   - Use the builder pattern to create user and options.
   - Replace `statsig.User{}` with `statsig.NewStatsigUserBuilder().With*().Build()`.
   - Initialize with `statsig.NewStatsig()` and call `Initialize()`.
4. **Test Thoroughly**:

   - Verify all feature gates, experiments, and configs work as expected.
   - Check that event logging is functioning correctly.

## New features available in Go Core

- **Parameter Stores**: Access to dynamic parameter management.
- **Improved Performance**: 5-10x faster evaluation times.
- **Better Error Handling**: More robust error management.

## Need help

If you encounter any issues during migration, reach out [in Slack](https://statsig.com/slack) or go to the [GitHub repository](https://github.com/statsig-io/statsig-server-core) for the latest updates and examples.