Deployment decoupled from release: Unleash, the most popular open-source feature management platform on GitHub, is a Node.js server backed by PostgreSQL. Ship code dark, then control who sees it through activation strategies: gradual percentage rollouts, targeting by user ID, IP, hostname, or application name, custom constraints against your own context fields, and scheduled or time-limited releases. Strategies stack - a flag activates if any strategy matches - and strategy variants layer A/B versions on top of the on/off decision. Each flag carries per-environment configurations, so a feature can run at 100% in staging while canarying at 5% in production. Backend SDKs (Node.js, Java, Go, Python, Ruby, .NET, PHP, Rust, and more) fetch configuration and evaluate flags locally, so a flag check adds zero network latency to request paths; frontend SDKs for React, Vue, Svelte, iOS, Android, and Flutter evaluate through a proxy layer. Flag hygiene is built in: flags are typed (release, experiment, operational, kill-switch, permission) with expected lifetimes, and Unleash marks overdue flags as potentially stale and surfaces unknown flags your SDKs request but that don't exist. Self-hosting via Docker keeps flag data, targeting rules, and evaluation infrastructure entirely on your side.

If editors should publish without waiting on developers, and developers should keep full control of the design, Umbraco is the free content management system built around that split. A page begins in the Block Grid editor, where reusable blocks nest inside Areas and each block is sized on a column and row grid. Live preview shows the result before anything goes out. Publish and unpublish times can be scheduled in the editor's own time zone, and any page can roll back to an earlier version from its Info tab. One content node can exist in several languages, and split view puts two of them side by side. The Media section holds images, video, and other files. Visitors can register and log in as members, new members can be placed in member groups, and pages can be hidden from anyone not logged in. On the code side, templates and partial views shape the front end, while the opt-in Content Delivery API returns content items as JSON for mobile apps and any other front end. Webhooks notify outside services when content is published, unpublished, or deleted. Custom dashboards and property editors extend the backoffice, and the Marketplace lists open-source and commercial packages for the rest. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Used by over 3,000 organizations including Dropbox, Khan Academy, Sony, Pepsi, Wikipedia, and Mistral, GrowthBook is the open-source experimentation platform that handles over 100 billion feature flag evaluations daily across its cloud and self-hosted deployments. Feature flags support advanced targeting with user attributes, gradual percentage rollouts, prerequisite dependencies, and scheduled launches, with both client and server SDKs evaluating flags locally from a cached payload for sub-millisecond performance with zero network calls per check. The warehouse-native architecture queries experiment results directly from 11 data sources including BigQuery, Snowflake, Databricks, Redshift, ClickHouse, Mixpanel, and PostgreSQL, eliminating duplicate data pipelines. The statistics engine implements CUPED variance reduction, sequential testing, Bayesian analysis, post-stratification, multi-armed bandits, and sample ratio mismatch checks with fully open-source methodology. Product analytics provides dashboards with funnels, retention cohorts, and event-based tracking shareable across teams. Twenty-four SDKs cover React, Next.js, Node.js, Python, Go, Ruby, PHP, Java/Kotlin, Swift, C#/.NET, Rust, Elixir, Angular, and edge runtimes including Cloudflare Workers, Fastly Compute, and Lambda@Edge. The MCP server and REST API enable AI coding agents to create features, start experiments, and manage stale flags programmatically. Self-hosting deploys via Docker Compose with MongoDB, or via Helm charts on Kubernetes, with the same codebase powering both open-source and managed cloud offerings. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Engineering and product teams ship code to production daily with FeatBit, an enterprise feature flag and experimentation platform that controls exactly which user segments, regions, or percentage rollouts see each new capability. When a regression appears in production, operators toggle an instant kill switch, dial back canary weights from full traffic to one percent, or restrict access to internal QA accounts without redeploying containers. Reusable user segments group customers by subscription tier, device property, or custom attributes for consistent targeting across environments. Server-side and client-side SDKs for .NET, Java, Go, Python, Node.js, React, React Native, JavaScript, and OpenFeature synchronize flag states over WebSockets in under 100 milliseconds and evaluate rules locally in memory. Built-in A/B/n experimentation links flag variations to custom conversion events, click tracking, and pageview metrics so teams can validate product hypotheses with live telemetry. Scheduled rollouts, multi-step approval workflows, flag triggers, and webhook integrations with Slack, Datadog, Grafana, New Relic, and OpenTelemetry keep release operations auditable. Role-based access control and single sign-on govern every flag change. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.