Hypertune is the most flexible platform for feature flags, A/B testing, analytics and app configuration.

• Static typing and code generation gives you full end-to-end type-safety across all your feature flags and inputs.
• Install 1 TypeScript SDK optimized for all JavaScript environments — browsers, servers, serverless, edge and mobile — with simple integrations for React and Next.js, compatible with Server Components and the App Router.
• Define type-safe, custom inputs like the current User, Organization, etc, and use them in feature flag rules to target exactly the users you want.
• Create variables like user segments that you can reuse across different feature flags, and instantly debug flags for each user.
• Git-style version history, diffs, branching and pull requests let you manage feature flags like you manage your code. Test and preview flag changes in isolated branches and safely approve them with pull requests. Avoid bad changes and see exactly what changed and when.
• A/B tests, percentage-based rollouts, multivariate tests and machine learning loops let you seamlessly rollout, test and optimize new features.
• Log analytics events with type-safe, custom payloads, and build flexible funnels and charts in the dashboard to measure the impact of every feature release.
• Local, synchronous, in-memory flag evaluation with zero network latency lets you safely access flags in any code path without affecting the end user experience.
• Static build-time snapshots of your feature flag logic let you use the SDK in local-only, offline mode and give you safe fallbacks in remote mode.
• Initialize the SDK with only the feature flags you need and partially evaluate flag logic on the edge for performance and security.

Hypertune scales beyond feature flags to powerful app configuration to let you manage:

• Permissions, access controls, billing logic, etc
• In-app copy, marketing content, etc
• Allowlists, redirect maps, timeouts, magic numbers, etc

ConfigCat is a developer-centric feature flag service that helps you turn features on and off, change their configuration, and roll them out gradually to your users. It supports targeting users by attributes, percentage-based rollouts, and segmentation. Available for all major programming languages and frameworks. Can be licensed as a SaaS or self-hosted. GDPR and ISO 27001 compliant.