Changelog

v0.1.0 - 2026-03-10

Initial release of LevelFour SDKs and API documentation.

API

• Standardized error responses across all endpoints
• Bearer auth via API keys (l4_live_ / l4_test_ prefixes)
• Offset-based pagination with x-fern-pagination support
• OpenAPI spec auto-generated from FastAPI

Python SDK (levelfour on PyPI)

• Sync (LevelFour) and async (AsyncLevelFour) clients
• API key validation and LEVELFOUR_API_KEY env var fallback
• Typed error hierarchy: AuthenticationError, NotFoundError, RateLimitError, etc.
• SyncPager / AsyncPager for automatic pagination
• WebhookVerifier for HMAC-SHA256 signature verification
• Per-request options via RequestOptions TypedDict

TypeScript SDK (levelfour on npm)

• LevelFourClient with full TypeScript type coverage
• Typed error classes: AuthenticationError, NotFoundError, RateLimitError, etc.
• Page async iterable for auto-pagination
• collectAll() helper for collecting all pages
• WebhookVerifier for signature verification
• HttpResponsePromise with .withRawResponse() for raw HTTP access

Go SDK (github.com/LevelFourAI/levelfour-go)

• levelfour.NewClient() with functional options pattern (WithBaseURL, WithMaxRetries, WithHTTPClient)
• Typed error structs with errors.As support
• Generic Page / PageIterator / CollectAll for pagination
• webhooks.Verifier for HMAC-SHA256 signature verification
• Per-request options via the option package

Documentation

• Developer portal with quickstart, SDK references, resource guides
• Auto-generated API reference from OpenAPI spec
• Guides for GitHub Actions and scheduled execution