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Fitness Data Standard (FDS)

Welcome to the Fitness Data Standard (FDS) documentation. FDS is an open, interoperable standard for exchanging fitness domain data across applications and platforms.

Purpose​

Enable data portability and interoperability across fitness applications by providing:

  • Normative JSON Schemas for core fitness entities
  • High-quality RFCs with examples and implementation guidance
  • Flexible extension points for platform-specific needs
  • Standardized metadata and lifecycle management

Current Scope​

In Scope:

  • Exercise data model (RFC-001)
  • Registry entities: Equipment (RFC-002), Muscles (RFC-003), Muscle Categories (RFC-004), Body Atlas (RFC-005)

Out of Scope (for now):

  • Workout/programming models
  • User progress tracking
  • Authentication/Authorization
  • (These will be covered by future RFCs)

Quick Start​

For Implementers​

  1. Browse the Specifications to understand the data models
  2. Explore the JSON Schemas with interactive viewers
  3. Validate your data against the schemas (see validation guide)
  4. Extend using the extension registry for custom needs

For Contributors​

  1. Review the Governance process
  2. Read the Contributing Guide
  3. Propose improvements via RFC process
  4. Join the community on GitHub

Documentation Structure​

Key Features​

Semantic Versioning​

FDS follows semantic versioning (X.Y.Z) with strict compatibility rules:

  • Major: Breaking changes to required fields
  • Minor: Backward-compatible additions
  • Patch: Non-functional changes (typos, editorial)

UUID Identifiers​

All production identifiers MUST be UUIDv4 strings for:

  • Exercise IDs
  • Equipment, Muscle, Category IDs
  • Cross-entity references

Flexible Extensions​

Two structured extension points:

  • attributes: Flat key/values for common extensions
  • extensions: Nested, vendor-scoped structures for complex data

Status Lifecycle​

Entities include metadata.status for lifecycle management:

  • draft → review → active → inactive / deprecated

Learn More​

License​

FDS is licensed under the VITNESS Open Standards License Agreement.

Ready to get started? Head to the Getting Started Guide →