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API · /goldenratio-api

Golden Ratio & Scale API

healthy 4,978 Subscribers

Design-proportion maths as an API, computed locally and deterministically. The divide endpoint splits a length by the golden section, the division beloved of artists and designers in which the whole is to the longer part as the longer is to the shorter, both ratios equal to φ = (1+√5)/2 ≈ 1.618 — so 100 splits into a 61.8 longer segment and a 38.2 shorter one — and can also extend a single segment to its larger or smaller golden partner. The rectangle endpoint gives the other side and the area of a golden rectangle from either side, the shape that leaves a smaller golden rectangle when you remove a square. The scale endpoint builds a modular (typographic) scale — base · ratio^step across a range of steps up and down — for harmonious type sizes and spacing, taking a numeric ratio or a named musical one such as minor-third (1.2), major-third (1.25), perfect-fourth (1.333) or golden (φ); a 16-base major-third scale gives 16, 20, 25, 31.25 and so on. Lengths are unit-agnostic. Everything is computed locally and deterministically, so it is instant and private. Ideal for graphic-design, web-design, UI, typography, layout and architecture app developers, type-scale and proportion tools, and design systems. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is proportion and scale; for pixel-density and print sizing use a PPI/DPI API.

#golden-ratio #typography #modular-scale #design #proportion #developer-tools
api.oanor.com/goldenratio-api
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Machine-readable spec so AI agents can integrate this API.

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

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API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
85 ms
Server probes · 24h
Subscribers
4,978
active
Total calls
28
last 7 days
status Full status page → · 12 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 6,400 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 6,400 calls/month
  • 2 req/sec
  • Golden section + rectangle + type scale
  • No credit card
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Starter

€4.95 /month

  • 64,000 calls / month
  • 6 requests / second
  • Hard cap (429 above quota, no overage)
  • 64,000 calls/month
  • 6 req/sec
  • Named ratios, multi-step scales
  • Email support
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Pro

€13.70 /month

  • 295,000 calls / month
  • 15 requests / second
  • Hard cap (429 above quota, no overage)
  • 295,000 calls/month
  • 15 req/sec
  • Design-system & tooling pipelines
  • Priority support
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Mega

€43.50 /month

  • 1,560,000 calls / month
  • 40 requests / second
  • Hard cap (429 above quota, no overage)
  • 1,560,000 calls/month
  • 40 req/sec
  • Platform scale
  • Dedicated SLA
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Related APIs

Other APIs with overlapping tags.

Modular Scale API

Generate a modular (geometric) scale for typography and spacing. Pick a base size and a ratio — a named musical interval (minor-second, major-second, minor-third, major-third, perfect-fourth, augmented-fourth, perfect-fifth, minor-sixth, golden, major-sixth, minor-seventh, major-seventh, octave and more), a plain number like 1.25, or an interval written as 3:2 — and the scale endpoint returns a harmonious set of sizes stepping up and down from the base, where each value is base × ratio^step (step 0 is the base). Choose how many steps above and below, the rounding, and an optional unit suffix (px, rem, em) so the values come back ready to paste into CSS or design tokens. The ratios endpoint lists every named ratio with its decimal value. A modular scale gives type, spacing and layout a consistent rhythm instead of arbitrary pixel values. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This produces a numeric size scale; for colour scales and gradients use the Gradient API.

api.oanor.com/modularscale-api

Fonts API

The Google Fonts catalogue as an API — 1,900+ open-source font families with everything you need to pick and embed a typeface. Look up a family (e.g. Roboto → category, available weights, variable-font axes, subsets and a ready-to-use CSS embed URL); search by name, category (Sans Serif, Serif, Display, Handwriting, Monospace), subset, weight or variable-font support; or list the most popular families. Each record carries the weights/styles, variable axes (wght, wdth, …), language subsets, designers, popularity rank and a Google Fonts CSS2 embed URL. Ideal for design tools, website builders, font pickers and theming systems.

api.oanor.com/fonts-api

Color Distance API

CIE colour science as an API: convert colours through the device-independent spaces and measure how different two colours really look. The convert endpoint takes a colour as hex, RGB or CIELAB and returns it in sRGB hex, RGB, CIE XYZ and CIELAB (D65 white point). The distance endpoint computes the perceptual difference between two colours with all three standard Delta-E formulas — CIE76 (plain Lab distance), CIE94, and CIEDE2000, the modern and most accurate metric — and tells you whether the difference is perceptible. The nearest endpoint finds the closest named colour to any colour by CIEDE2000. This is the maths behind colour matching, print and brand-colour QC, and tolerancing — distinct from simple hex/RGB/HSL conversion. Everything is computed locally and deterministically, so it is instant and private. Ideal for print and prepress, brand-colour compliance, textile and paint matching, image processing and computer vision, and design tooling. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 4 endpoints. This is CIE colour difference; for hex/RGB/HSL/CMYK conversion, palettes and WCAG contrast use a colour API.

api.oanor.com/colordelta-api

DPI & Print Size API

Resolution, print-size and pixel-density maths for print, design, photography and screens. The resolve endpoint takes any two of pixels, DPI and physical length and computes the third, returning the size in inches, centimetres, millimetres and points — so you can answer "how big will a 3000-pixel image print at 300 DPI" or "what DPI do I get printing 3000 px at 10 inches". The ppi endpoint computes a screen's pixel density from its resolution and diagonal size, plus the dot pitch in millimetres, the total megapixels and the aspect ratio. The convert endpoint converts a length between pixels, inches, centimetres, millimetres and points (PostScript points, 1/72 inch), using a DPI when pixels are involved. Everything is computed locally and deterministically, so it is instant and private. Ideal for print and prepress, graphic and web design, photography, and screen and display specs. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 4 endpoints. This is DPI and print-size maths; for aspect ratios and resizing use an aspect-ratio API and for general unit conversion use a unit API.

api.oanor.com/dpi-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Golden Ratio & Scale API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Golden Ratio & Scale API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Golden Ratio & Scale 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 Golden Ratio & Scale API cost?
Golden Ratio & Scale API has a free tier with 100 calls / month. Paid plans start at €4.95 / 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 Golden Ratio & Scale API GDPR-compliant?
All requests to Golden Ratio & Scale 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/goldenratio-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/goldenratio-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/goldenratio-api/SOME_PATH");
curl_setopt($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/goldenratio-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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