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API · /cod-api

Crystallography API

healthy 3,097 Subscribers

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).

#crystallography #materials-science #chemistry #minerals #crystal-structure #science
api.oanor.com/cod-api
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Machine-readable spec so AI agents can integrate this API.

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

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

Crystallography API — live data on the oanor API marketplace

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
418 ms
Server probes · 24h
Subscribers
3,097
active
Total calls
57
last 7 days
status Full status page → · 9 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 2,200 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 2,200 calls/month
  • 2 req/sec
  • Formula + text search + structure
  • No credit card
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Starter

€6.90 /month

  • 52,000 calls / month
  • 8 requests / second
  • Hard cap (429 above quota, no overage)
  • 52k calls/month
  • 8 req/sec
  • Full unit cell + space group
  • Email support
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Pro

€21.50 /month

  • 240,000 calls / month
  • 20 requests / second
  • Hard cap (429 above quota, no overage)
  • 240k calls/month
  • 20 req/sec
  • Materials & chemistry apps
  • Priority support
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Mega

€58.50 /month

  • 880,000 calls / month
  • 50 requests / second
  • Hard cap (429 above quota, no overage)
  • 880k calls/month
  • 50 req/sec
  • Research data platform
  • Dedicated SLA
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Related APIs

Other APIs with overlapping tags.

Bragg Diffraction API — oanor API marketplace

Bragg Diffraction API

X-ray crystallography maths as an API, computed locally and deterministically. The angle endpoint applies Bragg’s law, n·λ = 2·d·sinθ, to give the diffraction angle θ and the experimentally plotted 2θ from a crystal’s inter-planar spacing and the X-ray wavelength, defaulting to the common Cu Kα source at 0.15406 nm and reporting the highest observable order ⌊2d/λ⌋ — a 0.2 nm plane spacing diffracts Cu Kα to θ ≈ 22.65°, a 2θ peak near 45.3°. The spacing endpoint inverts the law, d = n·λ/(2·sinθ), reading the lattice spacing straight off a measured XRD peak — the everyday job of indexing a diffraction pattern, so a 2θ of 31.77° for table salt gives the 0.2814 nm (200) spacing. The wavelength endpoint solves λ = 2·d·sinθ/n to identify or calibrate the source. Lengths are entered in nanometres or ångström and angles in degrees, and any diffraction order n is supported. Everything is computed locally and deterministically, so it is instant and private. Ideal for materials-science, crystallography, mineralogy, XRD, semiconductor and solid-state-physics app developers, lattice-spacing and pattern-indexing tools, and laboratory software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is reflection-geometry Bragg diffraction with the 2d factor; for optical double-slit and grating diffraction use a wave-optics diffraction API.

api.oanor.com/bragg-api

 PDB API — oanor API marketplace

PDB API

The RCSB Protein Data Bank as an API — 3D macromolecular structures of proteins, nucleic acids and complexes, powered by the official RCSB PDB data and search services. Fetch a structure entry by its 4-character PDB id for its title, experimental method (X-ray, cryo-EM, NMR), resolution, keywords, deposit and release dates, authors, primary citation and entity & assembly counts; run full-text search across the whole archive returning matching PDB ids and the total hit count; read a polymer entity for its protein or nucleic-acid name, one-letter sequence, length, source organism, chains and linked UniProt ids; read a biological assembly for its oligomeric state, symmetry and chain & atom counts; list the ligands bound in a structure with their component ids and names; and look up any chemical component (ligand) by code for its formula, weight, SMILES and InChIKey. Ideal for structural-biology and drug-discovery tools, molecular viewers, bioinformatics pipelines, education apps and research dashboards.

api.oanor.com/pdb-api

 Elastic Moduli API — oanor API marketplace

Elastic Moduli API

Isotropic elastic-constant mechanics as an API, computed locally and deterministically. The convert endpoint takes any two of the five linear-elastic constants — Young’s modulus E, shear modulus G, bulk modulus K, Poisson’s ratio ν and the first Lamé parameter λ — and returns all five, using the standard isotropic relations (G = E/(2(1+ν)), K = E/(3(1−2ν)), λ = Eν/((1+ν)(1−2ν)) and their inversions for the pairs E+ν, G+ν, K+ν, E+G, E+K, K+G, G+λ, K+λ and λ+ν); steel given E = 200 GPa and ν = 0.3 comes back as G ≈ 76.92 GPa, K ≈ 166.67 GPa and λ ≈ 115.38 GPa. The wave-speeds endpoint computes the longitudinal (P) and shear (S) elastic wave speeds from two moduli and the density, vp = √((K + 4G/3)/ρ) and vs = √(G/ρ), together with the vp/vs ratio used in seismology and ultrasonic testing — steel comes out at about 5860 m/s for P-waves and 3130 m/s for S-waves. Moduli convert in whatever consistent unit you supply (the wave-speed endpoint expects strict SI: pascals and kg/m³ for metres per second). Everything is computed locally and deterministically, so it is instant and private. Ideal for materials-science, mechanical-engineering, geophysics, seismology, ultrasonic-NDT and FEA app developers, material-property and rock-physics tools, and simulation software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 2 endpoints. This interconverts elastic constants; for Young’s modulus from a stress/strain tensile test use a Young’s-modulus API.

api.oanor.com/elasticmoduli-api

 Isotopes API — oanor API marketplace

Isotopes API

Atomic isotope reference data as an API, built on the NIST Atomic Weights and Isotopic Compositions. For every known nuclide: its element (atomic number Z and symbol), mass number, relative atomic mass, natural isotopic composition (abundance) and the element's standard atomic weight. Look an isotope up by label (C-12, U-238) or by symbol + mass, list every isotope of an element, rank isotopes by mass or natural abundance, or search. A precise physics and chemistry reference for science, education, lab and engineering apps. Distinct from element-level data.

api.oanor.com/isotopes-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Crystallography API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Crystallography API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Crystallography 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 Crystallography API cost?
Crystallography API has a free tier with 100 calls / month. Paid plans start at €6.90 / 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 Crystallography API GDPR-compliant?
All requests to Crystallography 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.

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Code snippets

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

curl https://api.oanor.com/cod-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/cod-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/cod-api/SOME_PATH");
curl_setopt($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/cod-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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