The kernel is open, and works offline.
The rule format, the CLI, the checks, the packs and the MCP server are open source. Put standards in any repository as YAML, write them into every agent's instructions, and check every change, with no account and nothing leaving your machine.
Real output from a repository with no account and no network.
$ npx @groundrule/cli init --packs security-baseline,react ✓ Created .groundrule/config.yaml Packs security-baseline, react Agents AGENTS.md, CLAUDE.md, .cursor/rules/ $ npx @groundrule/cli sync groundrule sync · 32 standards → agents-md, claude-code, cursor ✓ Done. Commit these files so every agent gets the same rules. $ npx @groundrule/cli check --all ⚠ REACT-006 Give every img an alt attribute warning · deterministic (regex) src/components/Hero.tsx:1 → Add alt="what the image shows" for meaningful images, or alt="" if it is decorative. Passed ✓ 17 passed ⚠ 1 warning ◇ 14 guidance · 0.0s
Small, typed and tested. The repository checks itself with Groundrule on every change.
Eight packages, one command.
@groundrule/spec
The rule format: schemas and types for standards, packs, config, exceptions and findings, with generated JSON Schema for editors.
@groundrule/core
Loads a workspace (config, packs, overrides, exceptions), reads git changes, scopes rules and runs them.
@groundrule/evaluators
The checks: regex, files, dependencies, change-set and semgrep.
@groundrule/adapters
Writes AGENTS.md, CLAUDE.md, Cursor rules and Copilot instructions.
@groundrule/reporters
Terminal, JSON, SARIF and Markdown output.
@groundrule/packs
The 13 bundled packs and their 171 standards.
@groundrule/mcp
A small Model Context Protocol server: stdio, tools only, no dependencies.
@groundrule/cli
The groundrule command: init, sync, check, scan, explain, standards, doctor, propose, mcp, login.
A repository connects to the platform with one line in its config.
Everything a repository needs is open.
The platform adds what an organization needs: one rulebook across repositories, people and review, and evidence.
| Capability | Open source | Platform |
|---|---|---|
| Rule format, checks, packs | Yes | Yes |
| sync to every agent format, check locally and in CI | Yes | Yes |
| MCP server for agents | Yes | Yes |
| Your own standards as YAML in the repository | Yes | Yes |
| One rulebook shared by every repository | — | Yes |
| Teams, owners, roles and an audit log | — | Yes |
| Adopt and tune packs without forking, per team and repository | — | Yes |
| The review inbox, and imports from repositories, documents, apps and PR reviews | — | Yes |
| Evidence across repositories, impact previews and promotions | — | Yes |
| AI: describe a rule, find rules in documents, draft standards | — | Yes |
apiVersion: groundrule.dev/v1alpha1 kind: Config platform: org: acme-payments targets: [agents-md, claude-code, cursor] enforcement: scope: changed-lines # changed-lines | changed-files | all legacy: report # report | ignore | enforce failOn: blocker # blocker | warning | none
Issues and pull requests are welcome on GitHub.
About the open-source kernel.
What license?
Apache-2.0, for the rule format, the CLI, the checks, the packs and the MCP server.
Does the open-source CLI send anything anywhere?
Not unless you connect it. With no platform in .groundrule/config.yaml it runs entirely on your machine. Connected, it fetches your organization's rulebook, and uploads a scan or a proposal only when you run scan --upload or propose.
Can we run the platform ourselves?
Not today. The platform is a hosted service. The open-source kernel covers a single repository fully, with no account.
How do changes to the rule format happen?
Through an RFC in the repository, and they stay backward compatible within v1alpha1. Every field carries help text, so editors show it as you type.
Use it in one repository today.
npx @groundrule/cli init in any repository, no account. When your team wants one rulebook across every repository, create a workspace and connect it with one line.