# GemRate API

> Programmatic access to graded trading-card data: certs, population, history, and catalogs.

## Docs

- [Get population for a card](https://docs.gemrate.com/api-reference/cards/get-population-for-a-card.md): Returns a card's metadata and its current population summary, identified by its GemRate ID.
- [Get population history for a card](https://docs.gemrate.com/api-reference/cards/get-population-history-for-a-card.md): Returns the card's **current** population (the same `population` block as [`GET /v1/cards/{gemrate_id}`](#operation/getCard)) **plus** `history.by_grader` — one per-grader time series, each datapoint `{ date, total, gem_total, grades, qualifiers }` on the universal scale. The current population is t…
- [Download a catalog](https://docs.gemrate.com/api-reference/catalogs/download-a-catalog.md): Returns a temporary, presigned URL to download the catalog as a CSV. Fetch it promptly — it expires after `expires_in` seconds.
- [Get a certificate](https://docs.gemrate.com/api-reference/certificates/get-a-certificate.md): Returns the details of a single graded card (a "cert" — one physical copy), identified by its grading company and certificate number. The response includes the `gemrate_id` of the card this cert is a copy of, so you can follow it to the `/v1/cards` endpoints.
- [Get certificate images](https://docs.gemrate.com/api-reference/certificates/get-certificate-images.md): Returns image URLs for a certificate. If images are still being prepared, you'll get a `202` — retry shortly.
- [Universal grade map](https://docs.gemrate.com/api-reference/grades/universal-grade-map.md): The full **universal grade map**: every universal grade with each grading company's own label for it (`null` = the grader doesn't issue that grade), plus the PSA-only qualifier axis. This is reference data — the same scale all population and grade values in the API are reported on (see [Universal gr…
- [Resolve a grader spec to its card](https://docs.gemrate.com/api-reference/specs/resolve-a-grader-spec-to-its-card.md): A "spec" is a grading company's own catalog entry for a card (PSA calls it a spec; Beckett a price item, etc.). This resolves a spec to the card it refers to and returns the card's identity + a `spec` echo.
- [GemRate IDs](https://docs.gemrate.com/gemrate-id.md): How GemRate identifies cards — per-grader IDs and the universal ID.
- [Introduction](https://docs.gemrate.com/introduction.md): Programmatic access to graded trading-card data.
- [Universal grades](https://docs.gemrate.com/universal-grades.md): The one grade scale all population data is reported on, and how each grader's grades map onto it.

## OpenAPI Specs

- [openapi](https://docs.gemrate.com/openapi.yaml)