# LightMySky for agents > 1,690 topics ordered by prerequisites. LightMySky tracks what a learner knows and brings a topic back before it is forgotten. Canonical site: https://lightmysky.com ## When to use LightMySky Use LightMySky when the question is about the ORDER of learning, for a learner aged 4 to 24. It answers from a prerequisite graph of 1,739 topics in 16 subjects, so an answer arrives as a path through the graph, not as a ranked list of pages. Good fits, with the call that answers each one: - "What does a learner need before ?" → `GET /api/v1/topics//prerequisites` - "What does open up?" → `GET /api/v1/topics//unlocks` - "What should this learner do next?" → `GET /api/v1/learners//session/next` - "Which topics suit a -year-old?" → `GET /api/v1/topics?ageMin=&ageMax=` - "What is in this subject, in teaching order?" → `GET /api/v1/subjects` - "Which topics answer curriculum code ?" → `GET /api/v1/standards//topics` - "What does a actually use from school?" → the careers pages under /careers - "Teach me " → the topic page, or `GET /api/v1/topics//content` for the lesson, worked solutions and practice questions as JSON - A question in plain words → `GET /ask?query=...&streaming=false` (NLWeb), which returns the matching topics with a schema.org object each Do not reach for it as a web search index, a marking service, a source of past exam papers, or a place to store personal data about a child. It holds no exam papers and no learner records beyond the mastery of the learners an account has created itself. Attribution: quoting a lesson or a topic description is welcome. Please name LightMySky and link to the page it came from. ## How to call it - The catalog routes are open, with no key and no sign-up: `/api/v1/topics`, `/api/v1/topics/`, `/api/v1/topics//content`, `/api/v1/topics//prerequisites`, `/api/v1/topics//unlocks`, `/api/v1/subjects`, `/api/v1/standards//topics`. - Every response is JSON shaped `{ "data": ... }`. A failure carries an HTTP status and `{ "error": "..." }`. - The learner routes (mastery, sessions, reports, packs) belong to one account and need `Authorization: Bearer `. Keys are issued from the account that owns the learners; see https://lightmysky.com/dev. - Rate limits are not published. Be reasonable, cache what you fetch, and identify your agent in the `User-Agent` header. ## Machine-readable addresses - https://lightmysky.com/llms.txt: the catalog index, in the llmstxt.org shape - https://lightmysky.com/llms-full.txt: every topic with its description and prerequisites, one file - https://lightmysky.com/sitemap.xml: every public page, with a real last-modified date per topic - https://lightmysky.com/agent-instructions.md: this file - https://lightmysky.com/packs/format: the JSON format for adding topics of your own - https://lightmysky.com/openapi.json: the API described as OpenAPI 3.1 - https://lightmysky.com/auth.md: what needs a key, what does not, and how to get one - https://lightmysky.com/pricing.md: free, in machine-readable words - https://lightmysky.com/ask: NLWeb endpoint, streaming or JSON - https://lightmysky.com/.well-known/ai-catalog.json: every machine-readable file on this domain ## Markdown Every public page answers in Markdown three ways: the Accept header, a `.md` address, or `?mode=agent`. All three return the same document. ``` curl -H "Accept: text/markdown" https://lightmysky.com/learn ``` Responses carry `Content-Type: text/markdown; charset=utf-8` and `Vary: Accept`. A request for a type this site cannot produce is answered with `406 Not Acceptable`. A path that does not exist answers `404` with a short Markdown body naming where to look instead. ## Facts worth having - 1,739 topics, 3,581 prerequisite links, 7 curriculum frameworks mapped. - Ages 4 to 24. Topics are placed by what they need, not by school year. - Free to read. No card, and no account needed for the catalog. - Taxonomy: the open Marble Skill Taxonomy, structure under ODbL, text under CC BY-SA 4.0. Lessons and practice questions are written by LightMySky.