# Library of Congress

The US national library's online collections of photos, maps, manuscripts, newspapers, recordings and books, with a keyless JSON API plus IIIF image, full-text and streaming services.

- Category: Books and libraries · by Library of Congress (US)
- Website: https://www.loc.gov/
- Live data: no
- Checked on the official pages: 2026-10-23

## API

- Official API: yes, docs https://www.loc.gov/apis/
- Key needed: no
- Price: Free; limits: JSON/YAML API: 20 requests per minute (1-hour block if exceeded); Text and Image Services: 150/min; Streaming: 60/min; no paging past 100,000 items; recommended max 1,000 items per page.
- Base URL: https://www.loc.gov/
- Formats: json, yaml, iiif, xml

## Data and license

- Download: https://www.loc.gov/apis/ (json, xml, jpg, tiff, pdf, txt)
- License: Varies per item (Library generally does not own rights; many items public domain) (https://www.loc.gov/legal/); covers Each collection item; users must check copyright status themselves
- Commercial use with conditions
- Credit: not stated
- Embedding unclear
- Quote (api_official): "Specifically, it includes technical documentation of the Library's loc.gov JSON API, its sitemaps, and suite of microservices." (https://www.loc.gov/apis/)
- Quote (api_key): "The API is accessible to the public with no API key or authentication required. Rate limiting is strongly encouraged." (https://www.loc.gov/apis/json-and-yaml/working-within-limits/)
- Quote (limits): "JSON/YAML API for loc.gov Requests per minute 20 Time blocked, if rate is exceeded 1 hour" (https://www.loc.gov/apis/json-and-yaml/working-within-limits/)
- Quote (iiif): "Image Services provides an IIIF-compliant API for accessing and manipulating images from the Library of Congress." (https://www.loc.gov/apis/)
- Quote (site_rate): "Current guidelines recommend that software programs submit a total of no more than 10 requests per minute to our applications, regardless of the number of machines used to submit requests." (https://www.loc.gov/legal/)
- Quote (commercial): "As a publicly supported institution, we generally do not own the rights to materials in our collections. You should determine for yourself whether or not an item is protected by copyright or in the public domain, and then satisfy any copyright or use restrictions when publishing or distributing materials from our collections." (https://www.loc.gov/legal/)
- Quote (api_price): "The API is accessible to the public with no API key or authentication required. Rate limiting is strongly encouraged." (https://www.loc.gov/apis/json-and-yaml/working-within-limits/)

## Rules for an agent

- Add fo=json to almost any loc.gov search or item URL; keep to 20 req/min, pause on 429 or CAPTCHA HTML, and narrow with facets instead of deep paging.
- Stay at or below 20 requests/minute for the JSON API and back off on 429 or CAPTCHA pages.
- Check each item's rights statement before reuse; the Library does not grant rights.
- Do not page past 100,000 results; use facets or narrower queries.

Human page: https://agentgid.com/resources/library-of-congress/
Source: AgentGid (agentgid.com). Facts are quoted from the site's own pages; check the license page before you ship.