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API · /percentage-api

Percentage API

healthy 3,723 Subscribers

Everyday percentage maths as an API. Four clear operations: what is X% of a value (15% of 200 = 30); what percentage one number is of another (30 is 15% of 200); the percentage change between two numbers, with the direction and the raw difference (200 → 250 is a 25% increase); and applying a percentage increase or decrease to a value (200 + 15% = 230). Handy for discounts, tips and tax, growth and KPI deltas, progress bars, dashboards and quick spreadsheet-style sums — without writing a formula. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 5 endpoints. A focused calculator, distinct from a general math-expression engine.

#percentage #calculator #math #finance #utilities #developer-tools
api.oanor.com/percentage-api
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Machine-readable spec so AI agents can integrate this API.

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

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

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
86 ms
Server probes · 24h
Subscribers
3,723
active
Total calls
70
last 7 days
status Full status page → · 30 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 1,095 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 1,095 calls/month
  • 2 req/sec
  • Of + what + change + apply
  • No credit card
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Starter

€1.35 /month

  • 9,350 calls / month
  • 8 requests / second
  • Hard cap (429 above quota, no overage)
  • 9.35k calls/month
  • 8 req/sec
  • All four operations
  • Email support
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Pro

€21.25 /month

  • 144,500 calls / month
  • 20 requests / second
  • Hard cap (429 above quota, no overage)
  • 144.5k calls/month
  • 20 req/sec
  • Dashboard / finance pipelines
  • Priority support
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Mega

€59.25 /month

  • 765,000 calls / month
  • 50 requests / second
  • Hard cap (429 above quota, no overage)
  • 765k calls/month
  • 50 req/sec
  • Platform scale
  • Dedicated SLA
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Related APIs

Other APIs with overlapping tags.

Tip Calculator API

Work out tips and split a bill — with exact cent maths so the per-person amounts always add back up to the total, no penny ever lost to rounding. The calc endpoint takes a bill, a tip percentage (15% by default) and a number of people and returns the tip amount, the grand total, the per-person amount, the effective tip percentage, and — when you want a tidy number — an optional rounding of the total either up to the next whole unit or to the nearest. When the bill does not divide evenly it produces a fair share list where a few people pay one cent more, so the parts sum precisely. The split endpoint divides any amount, optionally adding a tip first, evenly among people and returns that exact per-person share list. Everything is computed in integer cents locally and deterministically, so it is instant, private and always balances. Currency-agnostic — the numbers work for any currency. Ideal for restaurant and POS apps, expense-sharing and group-payment tools, delivery and service apps, and everyday bill splitting. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This calculates tips and splits; for percentage maths in general use a percentage API and for invoicing margins use a margin API.

api.oanor.com/tip-api

GPA API

Calculate a weighted grade-point average (GPA). The calc endpoint takes a list of courses — each with a grade and the credit hours it is worth — and returns the credit-weighted GPA, the totals, and a per-course breakdown of quality points so you can see exactly how the average was formed. Grades may be US letter grades (A, A-, B+, … F) on the standard 4.0 scale, or 4.3 with the us_plus scale that gives A+ extra weight; percentages from 0 to 100 mapped to letters and points with the usual cutoffs; raw grade points given directly as numbers; or your own custom letter-to-point mapping for any institution's scheme. Courses can be passed as a JSON array or a compact string like "A:3,B+:4,C:2", and credits default to 1 for an unweighted average. The scales endpoint lists the built-in grade scales and their point values. Everything is computed locally and deterministically, so it is instant and private — no student data is stored. Ideal for student planners and dashboards, university and school portals, LMS and ed-tech apps, scholarship and admissions tools, and academic what-if calculators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This computes GPA; for general statistics use a statistics API.

api.oanor.com/gpa-api

Typing Speed API

Measure typing speed and accuracy. Compute words-per-minute, characters-per-minute and accuracy from a character (or word) count and the elapsed time, optionally subtracting uncorrected errors for a net WPM; compare what was typed against a reference text to count per-character mistakes and score the attempt; and estimate how long a given amount of text will take at a target speed. Uses the standard typing convention that one word equals five characters. Perfect for typing tests and games, coding-speed tools, onboarding and skills assessments, and leaderboards. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 4 endpoints. A focused typing calculator, distinct from general unit or percentage maths.

api.oanor.com/wpm-api

Running Pace API

A running-pace calculator as an API. Work out pace and speed from a distance and a time (pace per kilometre and per mile, plus km/h, mph and m/s); compute the finish time from a distance and a target pace; predict your time at another distance using Peter Riegel's formula (T2 = T1 × (D2/D1)^1.06) — e.g. estimate a half-marathon from a 10K; and generate a split-time table for even pacing. Times accept seconds, M:SS or H:MM:SS. Perfect for running and fitness apps, race planning, training logs and pace bands. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 5 endpoints. Distinct from general unit conversion and from body-metric (BMI/BMR) health calculators.

api.oanor.com/pace-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Percentage API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Percentage API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Percentage 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 Percentage API cost?
Percentage API has a free tier with 100 calls / month. Paid plans start at €1.35 / 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 Percentage API GDPR-compliant?
All requests to Percentage 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/percentage-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/percentage-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/percentage-api/SOME_PATH");
curl_setopt($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/percentage-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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