oanor
Sign up free
Marketplace Pricing Features Sign in

API · /ols-api

OLS Ontology API

healthy 3,774 Subscribers

The EMBL-EBI Ontology Lookup Service (OLS) as an API — a single access point to more than 280 biomedical and scientific ontologies and controlled vocabularies in one place: the Gene Ontology (GO), the Human Disease Ontology (DOID), the Human Phenotype Ontology (HP), ChEBI (chemical entities), Uberon (anatomy), the Experimental Factor Ontology (EFO), Mondo, NCIt and many more. /v1/search?q=diabetes searches terms across all ontologies (or restrict to one with ontology=doid), returning each match's label, OBO id (such as DOID:9351 or GO:0008150), ontology, IRI and a short definition. /v1/term?ontology=doid&id=DOID:9351 returns a single term's detail — its label, definition, IRI, synonyms and whether it is obsolete. /v1/ontologies browses the available ontologies with their id, title, description and number of terms. OBO ids look like DOID:9351, GO:0008150, HP:0000118 or CHEBI:15377. Ideal for biomedical natural-language processing, data annotation and harmonisation, autocomplete over scientific terminology, and semantic and knowledge-graph tooling. Data from EMBL-EBI OLS (open). This is a general ontology / controlled-vocabulary lookup spanning many domains — broader than a single medical thesaurus such as MeSH.

#ontology #ols #embl-ebi #biomedical #gene-ontology #controlled-vocabulary #semantic
api.oanor.com/ols-api
Get an API key Try in playground → Contact provider

Machine-readable spec so AI agents can integrate this API.

/api/ols-api/openapi.json
/api/ols-api/llms.txt

Discovery: GET /api/index.json lists every API.

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
974 ms
Server probes · 24h
Subscribers
3,774
active
Total calls
8
last 7 days
status Full status page → · 12 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 2,700 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 2700 calls/month
  • 2 req/sec
  • Search, term & ontology lookup
  • No credit card
Sign in to subscribe

Starter

€6.50 /month

  • 52,000 calls / month
  • 5 requests / second
  • Hard cap (429 above quota, no overage)
  • 52k calls/month
  • 5 req/sec
  • 280+ ontologies
  • Email support
Sign in to subscribe

Pro

€21.50 /month

  • 222,000 calls / month
  • 12 requests / second
  • Hard cap (429 above quota, no overage)
  • 222k calls/month
  • 12 req/sec
  • Annotation & NLP
  • Priority support
Sign in to subscribe

Mega

€59.00 /month

  • 800,000 calls / month
  • 35 requests / second
  • Hard cap (429 above quota, no overage)
  • 800k calls/month
  • 35 req/sec
  • High-throughput harmonisation
  • Dedicated SLA
Sign in to subscribe

Built by

P
PremiumApi

Related APIs

Other APIs with overlapping tags.

MeSH API

Medical Subject Headings (MeSH) as an API, powered by the U.S. National Library of Medicine's official MeSH RDF service. MeSH is the NLM's authoritative controlled vocabulary used to index the biomedical literature in PubMed — a curated thesaurus of diseases, anatomy, chemicals and drugs, organisms, psychiatry and psychology, analytical and diagnostic techniques, health care and more. Each concept is a "descriptor" with a stable unique id (e.g. D003920), a preferred name, a set of entry terms (synonyms and lay variants), and a list of allowable qualifiers (subheadings such as drug therapy, diagnosis or epidemiology). /v1/search?q=diabetes searches descriptors by their preferred name (match=contains, exact or startswith) and returns each descriptor's id and label. /v1/term?q=heart attack resolves a lay term or synonym to the MeSH descriptor(s) it belongs to, so colloquial language maps onto the controlled vocabulary (heart attack to Myocardial Infarction). /v1/descriptor?id=D003920 returns a descriptor's full record — its preferred name, all entry terms (synonyms), the allowable qualifiers and see-also cross-references, with a link to the MeSH browser. Ideal for biomedical natural-language processing and text mining, tagging and indexing literature, building clinical and research search tools, autocomplete over medical terminology, and mapping free text onto a standard ontology. Data from NLM MeSH (public domain). For drug-specific clinical nomenclature and interactions, see the RxNorm API.

api.oanor.com/mesh-api

Ontology API

Biomedical ontologies as an API, powered by the EBI Ontology Lookup Service (OLS). Search across 280+ curated ontologies — diseases (MONDO), human phenotypes (HP), the Gene Ontology (GO), anatomy (UBERON), cell types (CL), chemistry (ChEBI), experimental factors (EFO), the NCI Thesaurus and many more — to find terms by name; browse the full ontology catalogue with versions and term counts; read any term for its definition, exact synonyms, OBO id, IRI and obsolete status; and walk the class hierarchy through a term's direct parents and children. Ideal for clinical-data harmonisation and coding, biomedical search and autocomplete, knowledge-graph enrichment, annotation and curation pipelines, and research and EHR applications that need standard vocabularies. OBO ids look like MONDO:0005148 or GO:0008150.

api.oanor.com/ontology-api

BioSamples API

BioSamples as an API, powered by EMBL-EBI — the database that stores and links the metadata of biological samples, the physical specimens behind biological experiments. A sample in BioSamples carries a stable accession (such as SAMEA3231268) and a rich set of characteristics — organism, tissue or organism part, cell type, sex, disease, developmental stage, strain and any submitter-provided attributes — and is referenced by other EBI archives including the European Nucleotide Archive (ENA), ArrayExpress and PRIDE. /v1/search?q=liver searches samples by free text and returns each match's accession, name, organism and release date. /v1/sample?id=SAMEA3231268 returns a sample's metadata — its accession, name, NCBI taxon id, organism, release and update dates, the number of relationships to other samples, and its characteristics flattened to a clean key→value map. Accessions look like SAMEA…, SAMN… or SAMD…; get one from the search endpoint. Ideal for life-science data integration, sample tracking, metadata harmonisation and linking sequencing or expression data back to its source specimen. Data from EMBL-EBI BioSamples (public). This is a biological-sample metadata registry — distinct from study (BioStudies), sequence (ENA), variant (ClinVar) and structure databases.

api.oanor.com/biosamples-api

BioStudies API

BioStudies as an API, powered by EMBL-EBI — the database that holds the descriptions of biological studies and links their data together across EBI resources, including imaging (BioImage Archive), functional genomics (ArrayExpress), proteomics, and the literature (Europe PMC). Each study has an accession, a title and abstract, the collection it belongs to and links to its underlying data and publications. /v1/search?query=covid searches the studies and returns each match's accession (e.g. S-EPMC8017430), title, author, study type, release date and link/file counts. /v1/study?id=S-EPMC8017430 returns a study's metadata — its accession, the collection it belongs to (such as EuropePMC, ArrayExpress or BioImages), title, abstract, release date, authors and the number of linked resources. Accessions look like S-EPMC8017430 or S-BSST123; get one from the search endpoint. Ideal for research-data discovery, linking literature to its underlying datasets, systematic reviews and reproducibility tooling. Data from EMBL-EBI BioStudies (public). This is a studies and datasets metadata index — distinct from the sequence (UniProt, ENA), structure (PDB, EMDB), variant (ClinVar) and ontology databases.

api.oanor.com/biostudies-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for OLS Ontology API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call OLS Ontology API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for OLS Ontology API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does OLS Ontology API cost?
OLS Ontology API has a free tier with 100 calls / month. Paid plans start at €6.50 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is OLS Ontology API GDPR-compliant?
All requests to OLS Ontology API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Pick an endpoint from the list on the left to see its details and try it.

Code snippets

Sign up to get an API key, then call any path under your slug.

curl https://api.oanor.com/ols-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/ols-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/ols-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/ols-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

Ratings

Sign in to rate.

No reviews yet.

Discussion

Ask questions, share usage tips, get answers from the provider and other developers. Public — anyone can read.

Sign in to start a thread or reply.

Sign in

New thread

/ 4000

📌 Pinned 🔒 Locked

·

· ·

/ 4000

🔒 This thread is locked — no new replies.

  • No threads yet — start the discussion.

Support

Private 1:1 support with the provider — billing questions, integration issues, account problems. Only you and the provider team can see these threads.

Sign in to open a support ticket.

Sign in

Open new ticket

Describe what you need help with. The provider team gets an email and replies on the ticket page.

  • No tickets yet for this API.

Subscription active — calls can start immediately.

Send your first request —

Subscription active — copy a snippet and fire off your first call.