# Open Spanner

- [Open Spanner](/docs): Open-source usage and metering infrastructure.
- Overview
  - [What Is Open Spanner?](/docs/overview): The product model behind Open Spanner.
  - [Metering Infrastructure](/docs/overview/metering-infrastructure): How Open Spanner fits beside billing, analytics, and product services.
  - [Technical Overview](/docs/overview/technical-overview): How Open Spanner receives, stores, and queries usage.
  - [Release And Versioning Policy](/docs/overview/release-versioning): How Open Spanner versions the service and SDK packages.
- Getting Started
  - [Install Open Spanner](/docs/getting-started/core-service-installation): Start the complete product and record your first usage event.
  - [Choosing An SDK](/docs/getting-started/choosing-an-sdk): Pick an SDK for the service that reports usage.
  - [Query Your First Usage](/docs/getting-started/your-first-query): Read bucketed usage for a subject and meter.
- Concepts
  - [Meter Definition](/docs/concepts/meters): Define a metered product signal and how Open Spanner aggregates it.
  - [Meter Dimensions](/docs/concepts/meter-dimensions): Use meter dimensions to filter and group usage events.
  - [Usage Events](/docs/concepts/usage): Usage events are the raw facts Open Spanner stores before aggregation.
  - [Plans And Entitlements](/docs/concepts/plans-entitlements): Define plan quotas and check remaining usage.
  - [Alerts](/docs/concepts/alerts): Watch usage windows against thresholds.
  - [Auth Model](/docs/concepts/auth-model): Browser sessions for people, API keys for services.
  - [Workspace Access](/docs/concepts/workspace-access): Share metering data safely with role-based memberships and invitation links.
  - [Query Model](/docs/concepts/query-model): How usage events become buckets.
  - [Retention](/docs/concepts/retention): How long raw usage events are kept.
- Use Cases
  - [Use Cases](/docs/use-cases): Practical metering patterns you can build with Open Spanner.
  - [API Request Metering](/docs/use-cases/api-requests): Track API traffic, customer activity, and request mix.
  - [AI Token Usage](/docs/use-cases/ai-tokens): Meter token consumption across models, providers, and operations.
  - [Storage Usage](/docs/use-cases/storage-usage): Report capacity usage by tier, region, and resource type.
  - [Active Users](/docs/use-cases/active-users): Track seats, active users, workspaces, and plan-level adoption.
  - [Background Jobs](/docs/use-cases/background-jobs): Track asynchronous work, queue throughput, and job outcomes.
  - [Feature Usage](/docs/use-cases/feature-usage): Measure adoption and entitlement usage across product features.
  - [Historical Backfill](/docs/use-cases/historical-backfill): Import older usage safely with stable idempotency keys.
- Tutorials
  - [Meter An API Endpoint](/docs/tutorials/meter-an-api-endpoint): Record request usage from a backend API handler.
  - [Enforce Entitlements](/docs/tutorials/check-entitlements): Check or atomically consume a subject's plan quota.
  - [Retrying Usage Writes](/docs/tutorials/retrying-usage-writes): Use idempotency keys so retries do not double-count usage.
  - [Export Usage](/docs/tutorials/export-usage): Produce CSV usage data for billing, analytics, or audits.
- SDKs
  - [SDKs](/docs/sdks): Use Open Spanner from trusted backend services.
  - [Go](/docs/sdks/go): Use Open Spanner from Go services.
  - [TypeScript](/docs/sdks/typescript): Use Open Spanner from Node.js or TypeScript services.
  - [Python](/docs/sdks/python): Use Open Spanner from Python services and jobs.
  - [C#](/docs/sdks/csharp): Use Open Spanner from .NET services.
- Configuration
  - [Production Deployment](/docs/configuration/deployment): Run Open Spanner with durable storage, workers, and pinned container images.
  - [Database](/docs/configuration/database): Choose SQLite or Postgres storage for Open Spanner.
  - [Observability](/docs/configuration/observability): Scrape OpenTelemetry metrics for ingestion, API, database, and worker health.
  - [Quota Reconciliation](/docs/configuration/reconciliation): Detect quota drift and apply guarded counter repairs.
  - [Environment Variables](/docs/configuration/environment-variables): Runtime configuration for the Open Spanner service.
- Reference
  - [API Reference](/docs/reference/api-specification): Generated REST and gRPC contracts for Open Spanner.
- [FAQ](/docs/faq): Common Open Spanner questions.