Supported Languages

FlagShark supports detection of feature flags across 13 programming languages and all major feature flag providers. This page lists supported languages, file extensions, and SDK patterns.

Language Support Overview

Language	Extensions	Support Level	SDKs
TypeScript	.ts, .tsx	Full	LaunchDarkly, Unleash, Split, Custom
JavaScript	.js, .jsx, .mjs, .cjs	Full	LaunchDarkly, Unleash, Split, Custom
Go	.go	Full	LaunchDarkly, Unleash, Custom
Python	.py	Full	LaunchDarkly, Unleash, Custom
Rust	.rs	Full	LaunchDarkly, Custom
C#	.cs	Full	LaunchDarkly, Unleash, Custom
Java	.java	Basic	LaunchDarkly, Custom
Kotlin	.kt, .kts	Basic	LaunchDarkly, Custom
Ruby	.rb	Basic	LaunchDarkly, Custom
PHP	.php	Basic	LaunchDarkly, Custom
Swift	.swift	Basic	LaunchDarkly, Custom
C++	.cpp, .cc, .cxx, .hpp, .h	Basic	Custom
Objective-C	.m, .mm, .h	Basic	LaunchDarkly, Custom

Support Levels:

• Full: Comprehensive SDK support, extensively tested
• Basic: Core SDK patterns supported, custom configuration available

TypeScript & JavaScript

File Extensions

• .ts, .tsx (TypeScript)
• .js, .jsx (JavaScript)
• .mjs, .cjs (ES/CommonJS modules)

LaunchDarkly SDK

// React SDK
import { useFlags, useLDClient } from 'launchdarkly-react-client-sdk';

function MyComponent() {
  // Object destructuring - detected
  const { enableDarkMode, showBetaFeatures } = useFlags();
  
  // Client instance - detected
  const ldClient = useLDClient();
  const value = ldClient?.variation('flag-key', false);
}

// Node.js SDK
import LaunchDarkly from 'launchdarkly-node-server-sdk';

const client = LaunchDarkly.init('sdk-key');
// All variation methods detected
client.variation('flag-key', context, false);
client.boolVariation('flag-key', context, false);
client.stringVariation('flag-key', context, '');
client.numberVariation('flag-key', context, 0);
client.jsonVariation('flag-key', context, {});

Unleash SDK

// React SDK
import { useFlag, useVariant } from '@unleash/proxy-client-react';

function MyComponent() {
  const enabled = useFlag('feature-flag');
  const variant = useVariant('feature-flag');
}

// Node.js SDK
import { Unleash } from 'unleash-client';

const unleash = new Unleash({ /* config */ });
unleash.isEnabled('feature-flag');
unleash.getVariant('feature-flag');

Split SDK

// Browser SDK
import { SplitFactory } from '@splitsoftware/splitio';

const factory = SplitFactory({ /* config */ });
const client = factory.client();
client.getTreatment('feature-flag');
client.getTreatments(['flag-1', 'flag-2']);

Go

File Extensions

• .go

LaunchDarkly SDK

import (
    ld "github.com/launchdarkly/go-server-sdk/v7"
)

func main() {
    client, _ := ld.MakeClient("sdk-key", 5*time.Second)
    
    // All variation methods detected
    enabled, _ := client.BoolVariation("flag-key", context, false)
    str, _ := client.StringVariation("flag-key", context, "default")
    num, _ := client.IntVariation("flag-key", context, 0)
    float, _ := client.Float64Variation("flag-key", context, 0.0)
    json, _ := client.JSONVariation("flag-key", context, ldvalue.Null())
}

Unleash SDK

import "github.com/Unleash/unleash-client-go/v3"

func main() {
    unleash.Initialize(/* config */)
    
    enabled := unleash.IsEnabled("feature-flag")
    variant := unleash.GetVariant("feature-flag")
}

Python

File Extensions

• .py

LaunchDarkly SDK

import ldclient
from ldclient import Context

ldclient.set_config(Config("sdk-key"))
client = ldclient.get()

# All variation methods detected
enabled = client.variation("flag-key", context, False)
enabled = client.bool_variation("flag-key", context, False)
value = client.string_variation("flag-key", context, "default")
value = client.int_variation("flag-key", context, 0)
value = client.float_variation("flag-key", context, 0.0)
value = client.json_variation("flag-key", context, {})

Unleash SDK

from UnleashClient import UnleashClient

client = UnleashClient(url="...", app_name="...")
client.initialize_client()

enabled = client.is_enabled("feature-flag")
variant = client.get_variant("feature-flag")

Rust

File Extensions

• .rs

LaunchDarkly SDK

use launchdarkly_server_sdk::{Client, ConfigBuilder};

fn main() {
    let client = Client::build(ConfigBuilder::new("sdk-key")).unwrap();
    
    // Variation methods detected
    let enabled = client.bool_variation(&context, "flag-key", false);
    let value = client.string_variation(&context, "flag-key", "default");
    let value = client.int_variation(&context, "flag-key", 0);
    let value = client.float_variation(&context, "flag-key", 0.0);
}

C#

File Extensions

• .cs

LaunchDarkly SDK

using LaunchDarkly.Sdk;
using LaunchDarkly.Sdk.Server;

var client = new LdClient("sdk-key");

// All variation methods detected
bool enabled = client.BoolVariation("flag-key", context, false);
string value = client.StringVariation("flag-key", context, "default");
int value = client.IntVariation("flag-key", context, 0);
double value = client.DoubleVariation("flag-key", context, 0.0);
LdValue value = client.JsonVariation("flag-key", context, LdValue.Null);

Unleash SDK

using Unleash;

var unleash = new DefaultUnleash(config);

bool enabled = unleash.IsEnabled("feature-flag");
Variant variant = unleash.GetVariant("feature-flag");

Java

File Extensions

• .java

LaunchDarkly SDK

import com.launchdarkly.sdk.*;
import com.launchdarkly.sdk.server.*;

LDClient client = new LDClient("sdk-key");

// Variation methods detected
boolean enabled = client.boolVariation("flag-key", context, false);
String value = client.stringVariation("flag-key", context, "default");
int value = client.intVariation("flag-key", context, 0);
double value = client.doubleVariation("flag-key", context, 0.0);
LDValue value = client.jsonValueVariation("flag-key", context, LDValue.ofNull());

Kotlin

File Extensions

• .kt, .kts

LaunchDarkly SDK

import com.launchdarkly.sdk.*
import com.launchdarkly.sdk.server.*

val client = LDClient("sdk-key")

// Variation methods detected
val enabled = client.boolVariation("flag-key", context, false)
val value = client.stringVariation("flag-key", context, "default")
val value = client.intVariation("flag-key", context, 0)

Ruby

File Extensions

• .rb

LaunchDarkly SDK

require 'ldclient-rb'

client = LaunchDarkly::LDClient.new("sdk-key")

# Variation methods detected
enabled = client.variation("flag-key", context, false)
enabled = client.bool_variation("flag-key", context, false)
value = client.string_variation("flag-key", context, "default")
value = client.number_variation("flag-key", context, 0)

PHP

File Extensions

• .php

LaunchDarkly SDK

use LaunchDarkly\LDClient;

$client = new LDClient("sdk-key");

// Variation methods detected
$enabled = $client->variation("flag-key", $context, false);
$enabled = $client->boolVariation("flag-key", $context, false);
$value = $client->stringVariation("flag-key", $context, "default");
$value = $client->intVariation("flag-key", $context, 0);

Swift

File Extensions

• .swift

LaunchDarkly SDK

import LaunchDarkly

let client = LDClient.get()!

// Variation methods detected
let enabled = client.variation(forKey: "flag-key", defaultValue: false)
let value = client.variation(forKey: "flag-key", defaultValue: "default")

C++

File Extensions

• .cpp, .cc, .cxx, .hpp, .h

Custom Configuration Required

C++ support requires custom configuration in .flagshark.yaml:

providers:
  - name: "Custom C++ Flags"
    methods:
      - name: "isFeatureEnabled"
        flag_key_index: 0
      - name: "getFeatureValue"
        flag_key_index: 0

Objective-C

File Extensions

• .m, .mm, .h

LaunchDarkly SDK

@import LaunchDarkly;

LDClient *client = [LDClient get];

// Variation methods detected
BOOL enabled = [client boolVariationForKey:@"flag-key" defaultValue:NO];
NSString *value = [client stringVariationForKey:@"flag-key" defaultValue:@"default"];
NSInteger intValue = [client integerVariationForKey:@"flag-key" defaultValue:0];
double doubleValue = [client doubleVariationForKey:@"flag-key" defaultValue:0.0];

Custom Configuration

For custom Objective-C SDKs:

providers:
  - name: "Custom Obj-C Flags"
    methods:
      - name: "isFeatureEnabled:"
        flag_key_index: 0
      - name: "getFeatureValue:default:"
        flag_key_index: 0

Adding Custom SDKs

If your SDK isn't listed, you can add custom detection patterns:

# .flagshark.yaml
providers:
  - name: "Internal Feature Flags"
    package_path: "company/feature-flags"
    import_aliases: ["ff", "featureflags"]
    methods:
      - name: "isEnabled"
        flag_key_index: 0
        min_params: 1
      - name: "getValue"
        flag_key_index: 0
        min_params: 2

See Configuration for complete details.

Requesting New Language Support

Need support for a language not listed?

Related Documentation

• Flag Detection - How detection works
• Configuration - Custom provider setup
• Flag Not Detected - Troubleshooting