---
id: launchdarkly-server-sdk
version: "9.16.1"
license: Apache-2.0
license_treatment: permissive
maintenance: active
---

# launchdarkly-server-sdk — LaunchDarkly SDK for Python

License: permissive · Maintenance: active · Downloads: 11.8M/mo

## What it is and what it does

The LaunchDarkly Server-side SDK is a client library that connects your Python backend to LaunchDarkly's feature flag platform. It allows you to evaluate feature flags at runtime, enabling you to control feature rollouts, A/B tests, and gradual deployments without code changes or redeployment. The SDK handles flag evaluation, event tracking, and streaming updates from the LaunchDarkly service.

The package depends on standard HTTP and serialization libraries (urllib3, certifi, pyrfc3339, semver) plus LaunchDarkly's own eventsource library for server-sent event streaming. It's designed for server-side use where you control the SDK lifecycle and can maintain a persistent connection to LaunchDarkly. The SDK requires Python 3.10 or later and is actively maintained with regular updates.

Use it for:

- Roll out new features to a subset of users (beta testers) and gather feedback before full release.
- Gradually increase the percentage of users seeing a new feature while monitoring key metrics.
- Disable problematic features in production instantly without redeployment or restart.
- Grant feature access based on user attributes (e.g., payment tier, user group membership).
- Run A/B tests by serving different feature variants to different user cohorts.
- Manage maintenance windows by toggling dependent features on and off without downtime.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

A server-side SDK for integrating LaunchDarkly's feature flag service into Python applications, enabling runtime feature toggling and gradual rollouts without redeployment.

Yes. The SDK is actively maintained, has no known vulnerabilities, low install friction, and permissive licensing. It's well-suited for any Python backend that needs runtime feature control tied to LaunchDarkly's platform. Install if you are already using or planning to adopt LaunchDarkly; otherwise, evaluate whether the platform's cost and operational overhead fit your feature management needs.

## Install

pip install launchdarkly-server-sdk
uv add launchdarkly-server-sdk
poetry add launchdarkly-server-sdk

## Installing launchdarkly-server-sdk

Before you install: Low install friction with a pure-Python wheel and six stable runtime dependencies. Active maintenance with a release within the past month and recent repository activity.

License in practice: Apache-2.0 permissive license allows commercial and private use with minimal restrictions; suitable for most production environments.

Quickstart:

pip install launchdarkly-server-sdk

from launchdarkly_server_sdk import Context, Config

config = Config("your-sdk-key")
client = config.create_client()
context = Context.builder("user-key").build()
flag_value = client.variation("flag-key", context, False)

Requires Python 3.10 or later; requires a valid LaunchDarkly SDK key from the LaunchDarkly platform.

Verify before relying:

- Whether the SDK supports offline mode or local flag caching for resilience.
- Performance characteristics and throughput limits for high-volume flag evaluations.
- Exact event batching and network retry behavior under adverse conditions.

## Package facts

- License: Apache-2.0 (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 11.8M/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

feature flags python, feature management sdk, launchdarkly server sdk, runtime feature toggles, gradual rollout control, feature flag evaluation, server-side feature management, feature-flags, feature-management, continuous-delivery

[View on SkillFed](https://skillfed.io/packages/launchdarkly-server-sdk) · [View on PyPI](https://pypi.org/project/launchdarkly-server-sdk/)