// build feature flag configs with rollout & env support
Build lightweight feature flag config objects with defaults, environments, rollout percentages, and notes. Export to JSON, YAML, or JS.
No flags yet
Click "ADD FLAG" to define your first feature flagConfig will appear here
Add flags and click GenerateClick "ADD FLAG", give it a name, set its default state (on/off)
Expand each flag to set rollout %, environments, and a description note
Choose JSON, YAML, or JS output format, then copy or download
A feature flag (or feature toggle) is a config key that enables or disables functionality at runtime without deploying new code. This tool helps you design that config visually — with environment support, rollout targeting, and export to JSON, YAML, or JavaScript.
A feature flag (also called a feature toggle or feature switch) is a configuration value that controls whether a specific feature in your application is enabled or disabled — without requiring a code deployment.
Rollout percentage lets you gradually expose a feature to a portion of your users. For example, setting a flag to 25% means only 25% of users will see that feature — useful for canary releases and A/B tests.
Yes. Each flag supports per-environment toggles. You can enable a flag in dev and staging while keeping it disabled in prod, giving you safe testing before full release.
Use JSON for most backend integrations and APIs. Use YAML if your project uses YAML-based config files (e.g., Kubernetes, Helm, Ruby on Rails). Use JS if you want to import the config directly as an ES module in a frontend project.
No. Everything runs entirely in your browser. No data is sent to any server. Your feature flag configs stay private and local to your session.
Common conventions include snake_case (e.g. new_checkout_flow), SCREAMING_SNAKE_CASE for constants, or prefixed groups like feat_dark_mode. Stick with one convention across your project for consistency.
A Feature Flag Config Builder is a developer tool that helps you create structured configuration objects for feature toggles — the mechanism by which teams enable or disable application features at runtime without deploying code. This tool lets you visually define each flag, set its default enabled/disabled state, configure rollout percentages, specify which environments it applies to, and attach descriptive notes. It then exports your config to a portable format: JSON, YAML, or a JavaScript module.
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Feature flags are a cornerstone of modern continuous delivery. They decouple the act of deploying code from the act of releasing a feature. This separation has significant benefits:
A typical feature flag object contains several key fields. Understanding them helps you design configs that are both readable and functional:
snake_case or SCREAMING_SNAKE. Examples: new_billing_ui, ENABLE_DARK_MODE.dev, staging, and prod.JSON is the most universally supported format. It works natively in Node.js, Python, Java, Ruby, Go, and virtually every other runtime. Most feature flag systems (LaunchDarkly, Unleash, Flagsmith) accept JSON config imports. Choose JSON when you need maximum compatibility.
YAML is preferred in infrastructure-heavy environments. If your project uses Helm charts, Kubernetes manifests, Ansible playbooks, or Ruby on Rails, YAML is already your native config language. YAML is also more human-readable for long configs with nested structures, since it avoids bracket clutter.
JavaScript (ES Module) export is useful when your feature flag config lives inside the frontend bundle itself. This is common in React, Vue, and Svelte projects where flags are evaluated at build time or injected via environment variables. The exported JS object can be imported directly: import flags from './flags.config.js'.
Feature flags are powerful, but they can become technical debt if not managed carefully. Here are the most important practices:
enable_new_checkout_v2 is better than flag_42. Future-you will be grateful.enabled: true and enabled: false for every flag to prevent regressions.Most popular frameworks and deployment platforms have first-class support for feature flags. In React, you typically store flags in a context or Redux slice and gate components with conditional rendering. In Next.js, you can evaluate flags server-side via getServerSideProps for truly invisible feature gating. Laravel developers often use Pennant, the built-in feature flag package introduced in Laravel 10. Rails projects commonly use the Flipper gem. On the infrastructure side, platforms like AWS AppConfig, Azure App Configuration, and Google Cloud Firebase Remote Config offer hosted feature flag services that integrate with this tool's JSON export format.
This Feature Flag Config Builder is designed to fit into your development workflow quickly. Start by adding the flags you need for your current sprint or release. Set defaults and environment targets. Export the config to JSON and check it into your repository alongside your application code. If you use a hosted feature flag platform, use the JSON export as a starting point for bulk imports. For teams that manage flags as code, the YAML export integrates naturally with GitOps workflows where config files are version-controlled and reviewed via pull requests.