SDKs Overview

Flipswitch provides official SDKs with real-time updates via SSE. When you toggle a flag, connected clients update within milliseconds.

Official SDKs

JavaScript

React, Node.js, browser

Java

Spring Boot, server-side

Python

FastAPI, Django, server-side

Go

Gin, net/http, server-side

Feature Matrix

Feature	JavaScript	Java	Python	Go	OFREP
Flag evaluation	Yes	Yes	Yes	Yes	Yes
Real-time updates (SSE)	Yes	Yes	Yes	Yes	No
Automatic reconnection	Yes	Yes	Yes	Yes	No
Local caching	Yes	Yes	Yes	Yes	Varies
Event handlers	Yes	Yes	Yes	Yes	No
OpenFeature compatible	Yes	Yes	Yes	Yes	Yes

Quick Comparison

Use official SDKs when you need:

Instant flag updates (SSE)
Automatic cache invalidation
Event handlers for flag changes
Reconnection with backoff

Use standard OFREP when:

Your language doesn't have an official SDK
You only need polling-based evaluation
You want minimal dependencies

Installation

All SDKs follow the same pattern:

// 1. Create provider with API key
const provider = new FlipswitchProvider({ apiKey: 'YOUR_API_KEY' });
 
// 2. Register with OpenFeature
await OpenFeature.setProviderAndWait(provider);
 
// 3. Get client and evaluate
const client = OpenFeature.getClient();
const value = await client.getBooleanValue('my-flag', false);

See each SDK's page for language-specific details.

Configuration

All SDKs share common options:

Option	Default	Description
`apiKey`	required	Your environment API key
`baseUrl`	`https://api.flipswitch.dev`	Flipswitch server URL
`enableRealtime`	`true`	Enable SSE for instant updates

Evaluation Context

Pass user attributes for targeting:

const context = {
  targetingKey: 'user-123',      // Required: unique identifier
  email: 'user@example.com',     // Custom attributes
  plan: 'premium',
  country: 'SE'
};
 
const value = await client.getBooleanValue('feature', false, context);

The targetingKey is required for consistent gradual rollouts.

Other Languages

For languages without an official SDK, use any OpenFeature OFREP provider:

.NET
PHP
Ruby
Rust
Swift
Kotlin

Or call the Flag Evaluation API directly.