Core Concepts

Understanding these core concepts will help you use Replane effectively.

Projects

A project is a container for related configurations. Each project has its own:

• Set of configs
• Team members with roles
• API keys
• Audit log

Projects provide isolation between different applications or environments.

Configs

A config is a named JSON value that your application can fetch. Examples:

feature-flags

{
  "new-onboarding": true,
  "dark-mode": false,
  "billing-enabled": true
}

rate-limits

{
  "api-requests-per-minute": 100,
  "max-concurrent-connections": 50
}

Config Names

• Must be 1-100 characters long
• Can contain letters, digits, underscores, and hyphens
• Are unique within a project

Override Rules

Configs can have override rules that return different values based on context:

// Same config returns different values for different users
const limit = await client.getConfigValue('api-limit', {
  context: { tier: 'premium' }
});
// Returns higher limit for premium users

Overrides enable:

• User-specific configurations
• Tier-based limits
• Regional settings
• A/B testing variants
• Feature flags with targeting

Learn more in the Override Rules Guide.

Versions & Snapshots

Every time you update a config, Replane creates a new snapshot with:

• The new JSON value
• Who made the change
• When it was changed
• A unique version number

Snapshots are append-only — previous versions are never deleted. This enables:

• Full audit trail of all changes
• Instant rollback to any previous version
• Time-travel debugging

Realtime Updates (SSE)

When you use the SDK's watchConfigValue method, your application receives updates via Server-Sent Events (SSE):

const flags = await client.watchConfigValue('feature-flags');

// Later, when someone changes the config in the UI:
flags.get(); // Returns the new value automatically

No polling required. Changes propagate instantly.

JSON Schema Validation

Attach a JSON Schema to a config to enforce structure and prevent invalid values:

Example Schema

{
  "type": "object",
  "properties": {
    "new-onboarding": { "type": "boolean" },
    "dark-mode": { "type": "boolean" }
  },
  "required": ["new-onboarding", "dark-mode"],
  "additionalProperties": false
}

When a schema is attached, Replane validates all changes before saving. Invalid configs are rejected.

Roles & Permissions

Replane uses a unified three-tier role system across projects and configs:

Project Roles

Role	Permissions
Admin	Full project control: manage members, delete project, manage all configs and API keys
Maintainer	Manage configs and API keys, edit project details (cannot manage members or delete project)

Config Roles

Config-level roles provide granular access control for individual configs:

Role	Permissions
Maintainer	Full config access: edit value, schema, description, and manage config maintainers
Editor	Edit config value and description (cannot modify schema or maintainers)

Note: Project admins and maintainers automatically have config maintainer permissions for all configs in their project.

API Keys

API keys provide programmatic access to configs. Each key:

• Belongs to a specific project
• Can only access configs in that project
• Is shown once when created (store it securely)
• Can be revoked at any time

Use API keys in your SDKs:

const client = createReplaneClient({
  apiKey: process.env.REPLANE_API_KEY,
  baseUrl: 'https://your-replane-host.com',
});

Audit Log

The audit log tracks all activity:

• Config changes (who, when, what)
• Rollbacks
• Member invitations
• API key creation/revocation

The audit log is append-only and cannot be modified.

Next Steps

• Guides - Common use cases
• Self-Hosting - Deploy Replane
• JavaScript SDK - SDK documentation