feature-flags-nextjs

Evaluate PostHog feature flags server-side in Next.js by fetching flag values before the initial render. This ensures pre-render flag values are applied, preventing UI flicker during client hydration.

Yes, PostHog feature flags work with both the Next.js app router and pages router. The implementation covers client-side and server-side flag evaluation, bootstrapping, and server-to-client flag propagation for both routing methods.

Initialize PostHog in Next.js 15.3+ by configuring the client in instrumentation-client.ts/js. Use posthog-node for server-side flag fetching in server components and propagate those flags to the client.

Bootstrapping feature flags in Next.js means passing server-fetched flag values directly to the client during initial render. This allows immediate flag evaluation before the client-side PostHog instance fully loads.

Propagate server-side feature flag values to the Next.js client by evaluating them on the server using posthog-node and passing the resulting flag state down. This ensures the client renders with the correct flags immediately.

Yes, use posthog-node to fetch feature flags in Next.js server components. It enables server-side flag evaluation, allowing you to pass pre-render flag values to the client and avoid UI flicker.