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Available API

Units & Measurements

Complete searchable unit vocabulary, conversion engine, quantity kinds, systems, symbols, aliases, and provenance.

Test with your keyView pricing
Status
3/3 sources healthy
Contract
1.0.0
Data version
qudt-units-3.5.0-expanded
Current records
2,928
Normal pull
none
Full reconciliation
yearly verification

Coverage

What this API contains

Standardized measurement knowledge and dimension-safe conversion.

unitquantity kindmeasurement systemconversionprefixphysical constant

Endpoints

Built for direct use

/apis/units · 1 credit/apis/units/{id} · 1 credit/apis/units/search · 1 credit/apis/units/convert · 1 credit/apis/units/categories · 1 credit/apis/units/systems · 1 credit

Standard list, search, detail, relationship, and conversion calls cost one credit. Bulk exports cost 100 credits.

Bounded preview

See the shape of the data

These are up to five fixed records from the current release. The preview has no paging, search, or export controls. A developer account and API key are required to query the full dataset.

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Source record

Where the data comes from

Reference

NIST Guide for the Use of the International System of Units

authoritative SI guidance

Publisher
www.nist.gov
Last successful pull
Reference check only
License / terms
U.S. government publication; verify incorporated third-party material
Reuse review
Commercial: review_required · Redistribution: review_required
Healthy

QUDT Physical Constants Vocabulary 3.5.0

physical constants and source-qualified values

Publisher
qudt.org
Last successful pull
Aug 30, 2026 · 2:31 AM UTC
License / terms
CC BY 4.0
Reuse review
Commercial: True · Redistribution: True
Healthy

QUDT Prefix Vocabulary 3.5.0

prefix symbols, multipliers and identifiers

Publisher
qudt.org
Last successful pull
Aug 30, 2026 · 2:31 AM UTC
License / terms
CC BY 4.0
Reuse review
Commercial: True · Redistribution: True
Healthy

QUDT Units Vocabulary 3.5.0

structured normalization vocabulary

Publisher
qudt.org
Last successful pull
Aug 29, 2026 · 10:52 PM UTC
License / terms
CC BY 4.0 with embedded UCUM terms
Reuse review
Commercial: review_required · Redistribution: review_required