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API · /chemistry-api

Chemistry API

healthy 4,829 Subscribers

Chemical compound data as an API, powered by NIH PubChem (>100 million compounds). Look up any compound by common name, PubChem CID or SMILES and get its molecular formula, molecular and exact mass, IUPAC name, canonical SMILES, InChI and InChIKey, plus physicochemical properties (XLogP, TPSA, formal charge, hydrogen-bond donor/acceptor counts, rotatable bonds, heavy-atom count). List a compound's synonyms and trade/registry names, or resolve a name to PubChem CIDs. Ideal for cheminformatics, lab software, education, drug-discovery tooling and scientific data pipelines.

#chemistry #pubchem #compounds #molecules #cheminformatics #science
api.oanor.com/chemistry-api
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Machine-readable spec so AI agents can integrate this API.

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

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

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
420 ms
Server probes · 24h
Subscribers
4,829
active
Total calls
257
last 7 days
status Full status page → · 16 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 3,500 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 3,500 calls/month
  • 2 req/sec
  • Compound + synonyms + search
  • No credit card
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Starter

€6.00 /month

  • 50,000 calls / month
  • 8 requests / second
  • Hard cap (429 above quota, no overage)
  • 50k calls/month
  • 8 req/sec
  • name / CID / SMILES lookup
  • Email support
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Pro

€16.00 /month

  • 250,000 calls / month
  • 20 requests / second
  • Hard cap (429 above quota, no overage)
  • 250k calls/month
  • 20 req/sec
  • Cheminformatics / lab software
  • Priority support
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Mega

€42.00 /month

  • 1,250,000 calls / month
  • 50 requests / second
  • Hard cap (429 above quota, no overage)
  • 1.25M calls/month
  • 50 req/sec
  • Drug-discovery pipelines
  • Dedicated SLA
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Crystal structures as an API — powered by the Crystallography Open Database (COD), the open, public-domain collection of over 500,000 crystal structures of organic, inorganic, metal-organic compounds and minerals. Search the database by chemical formula (any standard casing — TiO2, Al2O3, H2O — is normalised automatically) or by free text over mineral names, titles and comments, then look up any structure to get its full crystallographic data: chemical and cell formula, space group (Hermann-Mauguin and Hall), the complete unit cell (a, b, c, alpha, beta, gamma and volume), the source publication (title, authors, journal, year, DOI) and a link to the CIF file. From quartz, calcite and diamond to anatase, corundum and diopside, it is ideal for materials science, solid-state chemistry, mineralogy, crystallography teaching and research tooling. This is a crystal-structure & materials database — distinct from molecule-property (chemistry / PubChem) and protein-structure (PDB) databases. Open data from the Crystallography Open Database (CC0 / public domain).

api.oanor.com/cod-api

Chemical Elements API

The complete periodic table as an API — all 119 chemical elements with their atomic and physical properties: atomic number and mass, category, phase, melting and boiling point, density, electron configuration, electronegativity, ionization energies and a short summary. Look up an element by symbol, atomic number or name, search and filter by category/phase/block, or fetch the whole table. Ideal for chemistry tools, education apps and science projects.

api.oanor.com/elements-api

KEGG API

The KEGG molecular database as an API, powered by the official KEGG REST service. KEGG (the Kyoto Encyclopedia of Genes and Genomes) links genomes, chemistry and disease. Fetch any KEGG entry parsed to JSON — a metabolic compound, KEGG Orthology group (KO), enzyme (EC number), reaction, module, drug, disease, glycan, gene or pathway map; search any KEGG database by name; list a database's entries; cross-link entries between databases (a gene to its pathways, a pathway to its compounds, an enzyme to its reactions); and convert KEGG identifiers to and from outside namespaces (NCBI Gene/Protein, UniProt, ChEBI, PubChem). Ideal for systems-biology and metabolomics pipelines, enzyme and orthology mapping, drug and disease research, gene-to-pathway annotation and bioinformatics id conversion. KEGG ids are letter-prefixed (C compound, K orthology, D drug, H disease, M module, R reaction, G glycan) or organism-coded (hsa human, eco E. coli).

api.oanor.com/kegg-api

ChEMBL API

The ChEMBL database of bioactive molecules as an API — the EBI's manually curated knowledgebase of drug-like compounds and their biological activity, powered by the official ChEMBL data API. Look up a compound by its ChEMBL id for its development phase, chemical structure (SMILES, InChIKey), molecular formula and weight, calculated properties (ALogP, polar surface area, hydrogen-bond donors/acceptors, Rule-of-Five violations, QED drug-likeness) and synonyms; search compounds by name; read a biological target with its organism and UniProt protein components; list a drug's mechanisms of action; list its approved and investigational indications (MeSH and EFO terms with development phase); and pull its measured bioactivities (IC50, Ki, EC50, potency…) with values, units, pChEMBL scores, assays and targets. Ideal for drug-discovery and cheminformatics pipelines, medicinal-chemistry and pharmacology tools, target-identification and SAR research, and life-science apps.

api.oanor.com/chembl-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Chemistry API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Chemistry API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Chemistry 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 Chemistry API cost?
Chemistry API has a free tier with 100 calls / month. Paid plans start at €6.00 / 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 Chemistry API GDPR-compliant?
All requests to Chemistry 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/chemistry-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/chemistry-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/chemistry-api/SOME_PATH");
curl_setopt($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/chemistry-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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