Open Source

Etapsky publishes all core libraries and the format specification as source-available code. This page explains what that means in practice, what license applies to each component, and how to contribute.

License Summary

Component	License	Notes
SDF format spec (spec/SDF_FORMAT.md)	CC-BY 4.0	Free to implement, reference, and extend
All code packages	BUSL-1.1	Converts to Apache-2.0 on 2030-03-17

Business Source License 1.1 (BUSL-1.1)

All Etapsky code — including @etapsky/sdf-kit, @etapsky/sdf-cli, @etapsky/sdf-schema-registry, @etapsky/sdf-server-core, @etapsky/cloud-sdk, and etapsky-sdf — is licensed under the Business Source License 1.1.

BUSL-1.1 is a source-available license with a time-limited commercial restriction. Here is what it means for you:

What you can do without restriction:

• Read the source code
• Fork the repository
• Use the software in development, testing, and non-production environments
• Build integrations and evaluate the software for commercial use
• Contribute pull requests

What requires a commercial license before the change date:

• Running the software in a production environment for commercial purposes

What happens on 2030-03-17:

• The license converts automatically to Apache-2.0 for all code released under BUSL-1.1
• No action required on your part — the code becomes fully open at that point

Note

The change date is baked into the license header of every published file. You can verify the conversion terms in the LICENSE file at the root of github.com/etapsky/sdf.

Change Date: 2030-03-17

Field	Value
License	Business Source License 1.1
Licensor	Etapsky Inc.
Change Date	2030-03-17
Change License	Apache License 2.0

For commercial licensing before the change date, contact hello@etapsky.com.

Format Specification — CC-BY 4.0

The SDF format specification (spec/SDF_FORMAT.md) is licensed separately under Creative Commons Attribution 4.0 International (CC-BY 4.0).

This means anyone can:

• Implement SDF in any language or platform
• Reference the specification in their own documentation
• Fork and extend the specification (with attribution)
• Build products based on SDF without a commercial license

The goal is to allow the SDF format to spread freely as an interoperability standard, independent of any single implementation.

Repositories

Repository	URL	Description
Main monorepo	github.com/etapsky/sdf	SDK, CLI, server, spec
SaaS platform	github.com/etapsky/sdf-cloud	api.etapsky.com infrastructure

Contributing

Contributions are welcome. The process:

1. Open an issue before starting significant work — this prevents duplicate effort and ensures alignment with the roadmap.
2. Fork the repository and create a branch from main.
3. Follow the existing code style. The project uses TypeScript strict mode — any is not permitted.
4. Add tests. The coverage gate is 80% minimum.
5. Submit a pull request. A maintainer will review within a reasonable timeframe.

Before contributing, read the contribution guidelines in CONTRIBUTING.md at the root of the repository.

Tip

Bug reports and feature requests are contributions too. A well-written issue that clearly describes a problem or use case is often more valuable than a pull request with a partial solution.

Code Style

• Language: TypeScript 5.7+ with strict mode
• Formatter: Prettier (config at repo root)
• Linter: ESLint (config at repo root)
• Package manager: Bun — use bun install, not npm install
• Test runner: Vitest

What We Accept

• Bug fixes with regression tests
• Documentation improvements
• New language bindings (coordinate first — we want to ensure format compliance)
• Schema examples for new document types
• Integration guides

What We Do Not Accept Without Prior Discussion

• New dependencies that conflict with the technology stack decisions in CLAUDE.md
• Changes to the format specification (spec/SDF_FORMAT.md) — spec changes require a separate discussion process
• Breaking changes to public APIs without a deprecation path