Feature flags screenshot
A hedgehog toggling a feature flag

Safely roll out features to specific users or groups

"Roll out new sidebar to 50% of users"

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What does it do?

Feature Flags let you turn features on or off for specific users, groups, or percentages of traffic without redeploying code. Create a flag, check it in your app, then control who sees what from PostHog – phased rollouts, kill switches, multivariate variants, JSON payloads, and beta opt-ins. When something breaks, flip it off. When it works, roll it out wider and measure the impact in analytics and session replay.

Who is it for?

Role
Use cases
Product Engineers
Ship behind a flag, canary to a slice of users, and kill a bad release without a redeploy
Product Managers
Control beta access and rollout percentage once engineering wires the flag into the product
Growth Engineers
Target cohorts, run multivariate variants, and measure impact next to analytics and replays
Platform / DevOps
Gate infrastructure changes and migrations with gradual rollouts and instant rollback
Support Engineers
Enable a fix or workaround for a specific customer without shipping a new build

How do I use it?

Manage flags from your editor

Create flags, configure targeting rules, and check rollout status from Cursor, Claude Code, VS Code, or any MCP-compatible agent.

Create flags while building features
Create a new feature flag with rollout percentage, targeting rules, and optional multivariate variants.
Check flags before deploying
Get the full definition of flags, including filters, groups, and payloads.
Clean up stale flags
List all active/inactive feature flags in the current project and find dead code to remove.
Update rollout rules
Update a flag's rollout percentage, targeting rules, or variants.

Install the PostHog MCP

Learn more
npx @posthog/wizard mcp add

Supports Next.js, React, Python, and

Key features

Multivariate feature flags

Boolean & multivariate feature flags

Test or release different versions of a feature with as many variants as you need.

Persist flags across authentication
Persist feature flags across authentication events so that flag values don't change when an anonymous user logs in and becomes identified.
Instant rollbacks
Disable a feature without touching your codebase

AI prompts

Ask PostHog AI to create flags, explain targeting, and clean up stale ones. Works in PostHog AI (in-app chat), PostHog Desktop (our AI code editor), and in your product editor (using the MCP). Already signed in? Click a prompt to try it.

Install

SDKs for web, mobile, and backend – or evaluate flags over the API.

Feature comparison

Optimizely
compare
LaunchDarkly
compare
Flagsmith
GrowthBook
compare
Statsig
compare
Automation
Trigger flag states based on schedules, triggers
✓
✓
✓
✓
Boolean flags
Simple on/off flags to enable or disable features
✓
✓
✓
✓
✓
✓
Early access feature opt-in widget
Allow users to opt in or out of specified features with a built-in widget or custom UI
✓
✗
✓
✗
✗
✗
Payloads
Pass structured data (strings, numbers, or JSON objects) to variants for dynamic configuration without code changes
✓
✗
✓
✓
✓
✓
Multivariate flags
Test multiple variants of a feature in a single flag
✓
✗
✓
✓
✓
✓
Release conditions
Target flags by user properties, cohorts, geographic location, or traffic percentage
✓
✗
✓
✗
✗
✓
Remote config
Replace hard-coded values in your app with remotely configurable parameters
✓
✓
✓
✓
Single-page app support
Use app frameworks like React and Vue
✓
✓
Flag usage logs
Track how many times a feature flag has been called
✓
✓
Implementation
Integrate flags efficiently across platforms
API access
Evaluate flags programmatically using PostHog API
✓
✗
✓
✓
✓
✓
Bootstrapping
Make flags available immediately on page load without waiting for API response
✓
✗
✓
✗
✗
✓
Local evaluation
Cache flag values for faster evaluation and reduced API calls
✓
✓
✓
✓
✓
✓
SDK support
Full support across all major SDKs including JavaScript, Python, Ruby, and more
✓
✓
✓
✓
✓
30+
Targeting
Precisely target who sees each feature
Percentage-based rollouts
Roll out features gradually to a percentage of users
✓
✓
✓
✓
✓
✓
Custom targeting
Target features based on user properties and attributes
✓
✓
✓
✓
✓
✓
Target by cohorts
Target features to specific user segments or behavioral cohorts
✓
✓
✓
✗
✗
✓
Geographic targeting
Limit flags to specific countries or regions based on IP address
✓
✗
✓
✗
✓
✓
Group-level targeting
Run flags at the organization, account, or team level for B2B products
✓
✗
✓
✗
✓
✓
Management
Operate flags safely at scale
Flag approvals
Require approvals to change flags
Scale
✗
Enterprise
✓
Enterprise
✓
Data source
Main source of data used by flags and A/B tests
First-party
First-party
Third-party
Third-party
Flag administration
Control who can modify flags with user roles and permissions
✓
✗
Enterprise
✗
✗
✓
Flag scheduling
Schedule flags to turn on or off automatically at specified times
✓
✓
Enterprise
✓
✓
✓
History and activity feed
See who hit a feature flag, the flag's value, and which page they were on
✓
✗
✓
✓
✗
✓
Instant rollbacks
Disable a feature without touching your codebase
✓
✗
✓
✗
✗
✓
Lifecycle management
Display new and old flags
✓
Enterprise
Multi-environment support
Use the same flag key across PostHog projects for local development or staging
Partial
✓
✓
✓
✓
✓
Flag permissioning
Control who can edit and modify flags
✓
✓
✓
✓
✓
✓
Triggers
Trigger changes based on metrics
✗
Enterprise
Testing
Tools for validating and debugging flags
Flag overrides
Override flag values locally for development and testing
✓
✗
✗
✗
✗
✓
Toolbar integration
Toggle flags directly from the PostHog toolbar while browsing your site
✓
✗
✓
✗
✗
✗
User assignment
Assign specific flag values to test users for manual testing
✓
✗
✓
✓
✗
✓
Experimentation
Use flags to power experiments and measure impact
Experimentation
Run A/B tests with feature flags integrated with experiments
✓
✗
✓
✓
✓
✓
Integration with analytics
View replays attached to a flag, analyze data based on a flag, and measure impact
✓
✗
✗
✗
✗
✓
Advanced
Additional capabilities for robust rollouts
Persist across authentication
Persist feature flags across authentication events so flag values don't change when users log in
✓
✗
✗
✗
✗
✓

Questions?

Answers

There are a few ways you can get answers to specific questions about Feature Flags.

  1. Check the docs

    We have an entire Wizard & Docs mini crestWizard & Docs Team dedicated to docs gardening.

  2. Read the pocket guide

    Follow a guided story that introduces Feature Flags one concept at a time.

  3. Search the community forums

    With over 100 discussions about Feature Flags, there's a good chance your question is already answered!

  4. Ask PostHog AI

    It's an incredibly useful AI chat that understands the product, docs, community questions, our codebase, GitHub issues, and industry knowledge.

  5. Talk to a human

    Dedicated humans are standing by and ready to assist. Best for questions about volume pricing, terms, and sexy legal stuff.

Works with other PostHog tools

Use Feature Flags with these other PostHog apps to maximize shareholder value.

And the rest of PostHog:

Get started – free

No credit card required. You get the first 1,000,000 requests free every month, then pricing starts at $0.0001/request and reduces with volume.

Install with AI

Run this command in your terminal or AI editor.
npx -y @posthog/wizard@latest

Supports Next.js, React, Python, and

Install without AI

Sign up for a free account and follow the install instructions for your stack.

Get started - free