What this endpoint does
At other/substance.json you will find Substance Data records pulled from FDA public datasets. Molecular-level substance information.
Who uses it
Historians, chemists, and data engineers dip into these supplementary files for substance identifiers, old press releases, and NDC reference material.
Example request
Paste this into a browser or our Explorer (swap the search term as needed):
GET https://api.fda.gov/other/substance.json?search=_exists_:uuid&limit=5You should see JSON with meta.results.total telling you how many matches exist.
Searching the data
Start with search=_exists_:uuid in our Explorer or your own HTTP client. Each endpoint documents its own field list on open.fda.gov. Common knobs: limit (how many rows), skip (offset for paging), sort (field:asc or field:desc), and count (aggregate unique values).
Tips that save time
Run a tiny limit=3 query first and read one full record before scaling up. Register a free API key if you plan to automate requests — it raises rate limits.
limit— usually capped at 1,000 per callskip— walk through large result setscount=some_field.exact— quick frequency tables
Before you rely on this data
openFDA Explorer is an independent website. We are not affiliated with, endorsed by, or operated by the U.S. Food and Drug Administration (FDA).
FDA public data is useful for research and general interest. It is not medical advice. Talk to a qualified healthcare professional about your health. openFDA data may be incomplete or reported voluntarily — treat it as a starting point, not a verdict.