diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 000000000..390e1cd77
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,160 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Repository Overview
+
+The Ghost SDK is a monorepo containing a collection of JavaScript/TypeScript packages for interacting with Ghost's APIs. It uses Lerna for monorepo management and Yarn workspaces.
+
+## Common Development Commands
+
+### Setup & Installation
+- **Initial setup**: `yarn setup` (mapped to `lerna bootstrap`)
+  - Installs all external dependencies
+  - Links all internal dependencies
+- **Install dependencies**: `yarn`
+
+### Testing
+- **Run all tests**: `yarn test` (runs `lerna run test`)
+  - This runs tests in all packages
+- **Run tests in specific package**: `cd packages/<package-name> && yarn test`
+- **Run tests with coverage**: Most packages use `NODE_ENV=testing c8 --all --reporter text --reporter cobertura mocha './test/**/*.test.js'`
+- **Run specific test file**: `NODE_ENV=testing mocha './test/specific.test.js'`
+- **Run tests matching pattern**: `NODE_ENV=testing mocha './test/**/*.test.js' --grep "pattern"`
+
+### Linting
+- **Run all linters**: `yarn lint` (runs `lerna run lint`)
+- **Run linter in specific package**: `cd packages/<package-name> && yarn lint`
+- **Fix linting issues**: `yarn lint -- --fix`
+
+### Building
+- **Build packages with build scripts**: Individual packages have their own build commands
+  - For packages with Rollup: `yarn build`
+  - TypeScript packages: Check for `tsconfig.json` and build scripts
+
+### Publishing
+- **Publish packages**: `yarn ship` (alias for `lerna publish`)
+  - Publishes all packages which have changed
+  - Updates any packages which depend on changed packages
+  - Use `yarn ship --git-remote upstream` when `origin` points to a fork and `upstream` points to the original TryGhost/SDK repo
+
+## Package Structure
+
+All packages are located in the `/packages` directory:
+
+### API Packages
+- **@tryghost/admin-api**: Admin API client for Ghost
+- **@tryghost/content-api**: Content API client for Ghost
+- **@tryghost/admin-api-schema**: JSON schemas for Admin API
+
+### Utility Packages
+- **@tryghost/helpers**: Template helpers (reading time, tags, etc.)
+- **@tryghost/helpers-gatsby**: Gatsby-specific helpers
+- **@tryghost/url-utils**: URL manipulation utilities
+- **@tryghost/string**: String manipulation (slugify, escapeHtml, etc.)
+- **@tryghost/color-utils**: Color manipulation utilities
+- **@tryghost/config-url-helpers**: URL configuration helpers
+- **@tryghost/social-urls**: Social media URL generation
+- **@tryghost/schema-org**: Schema.org structured data generation
+- **@tryghost/timezone-data**: Timezone data utilities
+
+### Content Processing
+- **@tryghost/html-to-plaintext**: HTML to plaintext conversion
+- **@tryghost/html-to-mobiledoc**: HTML to Mobiledoc conversion
+- **@tryghost/image-transform**: Image transformation utilities
+
+### Infrastructure
+- **@tryghost/limit-service**: Centralized limit enforcement
+- **@tryghost/adapter-base-cache**: Base cache adapter
+- **@tryghost/members-csv**: CSV parsing for members import/export
+- **@tryghost/referrer-parser**: Referrer parsing utilities
+
+### Frontend Packages
+- **@tryghost/custom-fonts**: Custom font utilities
+
+## Testing Approach
+
+- Testing framework: **Mocha** with **Should.js** for assertions
+- Mocking: **Sinon** for stubs and mocks
+- Coverage: **c8** for code coverage
+- Environment: Set `NODE_ENV=testing` when running tests
+
+### Test Structure
+```
+packages/<package-name>/
+├── test/
+│   ├── unit/          # Unit tests (if separated)
+│   ├── integration/   # Integration tests (if separated)
+│   ├── fixtures/      # Test fixtures and mock data
+│   └── utils/         # Test utilities
+│       ├── assertions.js
+│       ├── index.js
+│       └── overrides.js
+```
+
+## Adding New Packages
+
+To add a new package to the repo:
+1. Install [slimer](https://github.com/TryGhost/slimer)
+2. Run `slimer new <package name>`
+
+## Build Systems
+
+Different packages use different build systems:
+
+### Rollup-based packages
+- **content-api**, **timezone-data**, **helpers**, **color-utils**
+- Build command: `yarn build`
+- Configuration: `rollup.config.js`
+- Outputs: `cjs/`, `es/`, `umd/` directories
+
+### TypeScript packages
+- **color-utils**, **timezone-data**, **custom-fonts**, **referrer-parser**
+- Configuration: `tsconfig.json`
+- Some use Vite for building
+
+### Plain JavaScript packages
+- Most other packages don't require building
+- Source in `lib/` directory
+
+## Important Notes
+
+- This is a Yarn workspaces monorepo - always use `yarn`, not `npm`
+- The main branch is `master` (not `main`) for pull requests
+- All packages are published under the `@tryghost` scope
+- Packages have independent versioning
+- ESLint configuration uses `eslint-plugin-ghost`
+- Most packages follow similar patterns for structure and testing
+
+## Environment Variables
+
+- `NODE_ENV=testing` - Required for running tests
+- `GHOST_UPSTREAM` - Set remote for publishing (defaults to `origin`)
+
+## Git Configuration
+
+- Default branch for PRs: `main`
+- Publishing allowed from: `main` branch
+- Commit message for version updates: "Published new versions"
+
+## Common Patterns
+
+### Error Handling
+- Most packages use `@tryghost/errors` for consistent error formatting
+
+### Database Integration
+- Packages expecting database access use Knex instances
+- Support for transactions via `options.transacting`
+
+### API Versioning
+- API packages support multiple versions (v2, v3, v4, v5, v6, canary)
+- Version-specific tests in `test/<package>-test/v*.test.js`
+
+## Development Tips
+
+1. Run tests before committing
+2. Use `yarn lint` to check code style
+3. Follow existing patterns in the codebase
+4. Add tests for new functionality
+5. Update README.md in package directory for significant changes
+6. Use semantic versioning for package updates