PostHog feature flags for Node.js

Reference files

• references/nodejs.md

  - Node.js feature flags installation - docs

• references/adding-feature-flag-code.md

  - Adding feature flag code - docs

• references/best-practices.md

  - Feature flag best practices - docs

Key principles

• Environment variables: Always use environment variables for PostHog keys. Never hardcode them.
• Minimal changes: Add feature flag code alongside existing logic. Don't replace or restructure existing code.
• Boolean flags first: Default to boolean flag checks unless the user specifically asks for multivariate flags.
• Server-side when possible: Prefer server-side flag evaluation to avoid UI flicker.

PostHog MCP tools

Framework guidelines