API Reference

Machine-readable ground truth for Python and JavaScript libraries. All endpoints return JSON.

Base URL: https://checklist.day v1

Authentication

Pass your API key in the request header:

X-API-Key: your_api_key

Authentication is not yet enforced. Build against the header now so your integration is ready when it goes live.

Registry

Ground truth for library imports, install commands, CLI info, and install compatibility across Python runtimes.

GET /v1/registry

Paginated index of all registry entries.

Param	Type	Description
cursor	number	Last seen ID for pagination (default: 0)
limit	number	Page size, max 100 (default: 100)
language	string	Filter by language: `python`, `javascript`
tag	string	Filter by install tag: `verified`, `reviewed`, `draft`, `stale`

{
  "cursor": 0,
  "next_cursor": 100,
  "count": 100,
  "docs": [
    {
      "library": "chromadb",
      "title": "ChromaDB",
      "description": "...",
      "language": "python",
      "status": "active",
      "install_tag": "verified",
      "url": "https://checklist.day/v1/registry/chromadb"
    }
  ]
}

GET /v1/registry/{library}

Full doc for a single library — install commands, imports, auth, quickstart, and compatibility.

{
  "library": "chromadb",
  "title": "ChromaDB",
  "description": "...",
  "language": "python",
  "status": "active",
  "last_verified": "2026-05-13",
  "install": {
    "commands": ["pip install chromadb"],
    "cli": { "name": "chroma", "version": "chroma 0.6.3" }
  },
  "imports": ["import chromadb"],
  "auth": { "required": false, "env_vars": [] },
  "quickstart": { "code": "...", "lang": "python", "tag": "verified", ... },
  "compatibility": { "tag": "verified", "summary": { ... }, "results": [ ... ] }
}

GET /v1/registry/{library}/install

Install commands and CLI info only.

{
  "library": "chromadb",
  "commands": ["pip install chromadb", "pip install chromadb-client"],
  "cli": { "name": "chroma", "version": "chroma 0.6.3" }
}

GET /v1/registry/{library}/imports

Verified correct import statements only.

{
  "library": "chromadb",
  "imports": ["import chromadb"]
}

GET /v1/registry/{library}/compatibility

Full install compatibility matrix — tested across Python versions and OS/libc variants.

{
  "library": "chromadb",
  "tag": "verified",
  "last_tested": "2026-05-12",
  "installed_version": "1.5.9",
  "pypi_latest": "1.5.9",
  "is_stale": false,
  "summary": {
    "python_range": "3.9–3.13",
    "success_rate": 100,
    "avg_install_s": 4.9,
    "avg_import_s": 1.8,
    "wheel_type": "wheel"
  },
  "results": [
    {
      "runtime": "python:3.11-slim",
      "python_version": "3.11",
      "os_libc": "slim (glibc)",
      "variant": "default",
      "exit_code": 0,
      "wheel_type": "wheel",
      "install_time_s": 4.9,
      "import_time_s": 1.79,
      "mem_mb": 36.9,
      "disk_size": "41M",
      "import_side_effects": "clean",
      "failure_reason": null
    }
  ]
}

GET /v1/registry/{library}/compatibility/{runtime}

Compatibility data for a single runtime. URL-encode the runtime value.

Example: /v1/registry/chromadb/compatibility/python%3A3.11-slim

{
  "library": "chromadb",
  "runtime": "python:3.11-slim",
  "results": [ { ... } ]
}

GET /v1/registry/{library}/quickstart

Quickstart code and eval results across runtimes.

{
  "library": "chromadb",
  "code": "import chromadb
client = chromadb.Client()
...",
  "lang": "python",
  "tag": "verified",
  "last_tested": "2026-05-12",
  "results": [
    { "runtime": "python:3.11-slim", "exit_code": 0 }
  ]
}

Checklists

Executable task primitives — verified Python patterns for common agentic tasks.

GET /v1/checklists

Index of all available checklists.

{
  "total": 14,
  "checklists": [
    {
      "slug": "openai-chat-completion",
      "primitive": "llm-call",
      "description": "...",
      "registry_refs": ["openai"],
      "tags": ["openai", "llm"],
      "auth_required": true,
      "verified": true,
      "last_verified": "2026-04-10",
      "url": "https://checklist.day/v1/checklists/openai-chat-completion"
    }
  ]
}

GET /v1/checklists/{slug}

Full checklist including executable Python source code.

{
  "slug": "openai-chat-completion",
  "primitive": "llm-call",
  "description": "...",
  "registry_refs": ["openai"],
  "tags": ["openai", "llm"],
  "auth_required": true,
  "verified": true,
  "last_verified": "2026-04-10",
  "code": "# primitive: llm-call
# ...
import openai
...",
  "url": "https://checklist.day/v1/checklists/openai-chat-completion"
}

Legacy endpoints

These endpoints are stable and will not change. Existing integrations do not need to migrate.

Endpoint	Description
`GET /api/registry`	Full registry index (unversioned)
`GET /api/registry/{library}`	Full registry doc (unversioned)
`GET /api/checklists`	Checklists index (unversioned)