Design Token Single Source of Truth

A design token single source of truth establishes one authoritative location for token definitions that all other systems derive from. Without a clear source of truth, token values can diverge between design tools, code repositories, and documentation, creating inconsistency that undermines the purpose of having tokens. Establishing and maintaining a single source of truth is foundational to effective token management.

What Is a Design Token Single Source of Truth

A design token single source of truth is the designated authoritative location where canonical token definitions live. All other representations of tokens, whether in design tools, different codebases, or documentation, derive from this source and should match it.

The source of truth can be a code repository, a design tool, or a dedicated token management platform. What matters is that one location is authoritative while others are consumers or mirrors of that authority.

How Design Token Single Source of Truth Works

Establishing a single source of truth requires designating where tokens originate and how changes flow to other systems.

Code as source of truth places JSON or similar token files in a version-controlled repository. This is the most common pattern:

tokens-repo/
  tokens/
    color/
      primitive.json
      semantic.json
    spacing.json
    typography.json
  build/
    config.js

Changes to tokens happen through pull requests to this repository. Design tools import from or synchronize with this source. Build pipelines generate outputs for all platforms.

Design tool as source of truth uses Figma or another design application as the canonical location. Designers maintain tokens in the tool, and synchronization pushes changes to code repositories.

This pattern works when designers drive most token decisions and development primarily consumes rather than creates tokens.

Platform as source of truth uses a dedicated token management platform (Specify, Supernova, etc.) as the central hub. Both design tools and code repositories connect to this platform, which manages synchronization in all directions.

Regardless of which location serves as source, the principle remains: one location is authoritative, others reflect that authority.

Key Considerations

• Every team member must know where the source of truth lives
• Changes should only be made at the source, not in derived locations
• Synchronization processes must keep derived locations updated
• Conflicts indicate synchronization failure or unauthorized changes
• Version control at the source enables history and rollback
• Access controls protect the source from unauthorized modification
• Documentation should clearly state the source of truth location
• Auditing verifies that derived locations match the source

Common Questions

How should ownership be assigned?

Single source of truth works best with clear ownership. Ownership determines who can modify tokens and who makes decisions when conflicts arise.

Design system team ownership assigns token authority to a central team. This team reviews and approves all token changes, maintaining consistency and quality. This model works well for core tokens affecting the entire system.

Distributed ownership allows different teams to own different token categories. The design system team might own primitives and core semantics while product teams own product-specific tokens. Clear boundaries prevent overlap.

Hybrid ownership combines approaches: tight central control for foundation tokens with more distributed authority for extension tokens. This balances consistency with team autonomy.

Whatever the model, ownership should be documented and understood. When questions arise about whether a change is appropriate, ownership determines who decides.

What happens when sources diverge?

Divergence occurs when a derived location differs from the source of truth. This indicates either synchronization failure or unauthorized changes.

Detection mechanisms should identify divergence quickly. Automated comparisons between source and derived locations can run on schedules or as part of CI processes:

function checkDivergence(sourceTokens, derivedTokens) {
  const differences = [];
  for (const [name, value] of Object.entries(sourceTokens)) {
    if (derivedTokens[name] !== value) {
      differences.push({ name, source: value, derived: derivedTokens[name] });
    }
  }
  return differences;
}

Resolution typically means updating derived locations to match the source. If the derived location has legitimate changes that should be preserved, those changes should be applied to the source first, then propagated properly.

Investigation should determine why divergence occurred. Synchronization bugs, manual edits in wrong locations, or process gaps all have different remedies.

How should migration to a single source happen?

Organizations with tokens in multiple locations need migration strategies to consolidate to a single source.

Audit existing tokens across all locations. Identify what exists where, which versions are most current, and where conflicts exist between locations.

Choose the authoritative source based on workflow fit, technical capability, and team preferences. The choice should serve long-term needs, not just current convenience.

Consolidate tokens into the chosen source. Resolve conflicts by determining which values are correct and ensuring the source contains accurate, complete definitions.

Establish synchronization connecting the source to derived locations. Test that changes at the source propagate correctly.

Deprecate direct editing in derived locations. Communication and process changes ensure team members modify only the source.

Monitor for divergence to verify the single source of truth remains effective. Automated checks and periodic audits maintain discipline.

Summary

A design token single source of truth establishes one authoritative location for token definitions, preventing the divergence that undermines token system value. Whether located in code, design tools, or dedicated platforms, the source of truth requires clear ownership, proper synchronization to derived locations, and monitoring to detect divergence. Migrating to a single source involves auditing existing tokens, choosing and populating the authoritative location, and establishing processes that maintain source authority.