Querying UNII List (other/unii.json)

What this endpoint does

UNII List lives at other/unii.json. Unique Ingredient Identifier records. openFDA returns everything as JSON with a meta block (hit counts, disclaimers) and a results array.

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/unii.json?search=substance_name:water&limit=5

You should see JSON with meta.results.total telling you how many matches exist.

Searching the data

Start with search=substance_name:water 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

Wrap exact phrases in quotes inside the search parameter. Use count=field.exact when you want top values instead of raw rows.

• limit — usually capped at 1,000 per call
• skip — walk through large result sets
• count=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.