oanor
Sign up free
Marketplace Pricing Features Sign in

API · /entropy-api

Entropy API

healthy 3,717 Subscribers

Measure the information content of text. The analyze endpoint computes the Shannon entropy in bits per symbol, the total information in bits and bytes, the maximum possible entropy for the alphabet that was actually used, and a normalized 0–1 score that says how uniform (random-looking) the distribution is — over Unicode code points or raw UTF-8 bytes. The frequency endpoint returns the full character-frequency distribution, most common symbol first, with counts and percentages, showing control characters escaped and bytes as hex. It is exact, deterministic and runs entirely locally with no network calls, so it is instant and private. Ideal for randomness and password-quality checks, estimating how compressible data is, language and classical-cipher analysis, spotting low-variety or repetitive input, and feature extraction for text classification. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This measures information content; for password-strength scoring use a password API, for number statistics use a statistics API, and for grapheme/character counts use a text-segmentation API.

#entropy #shannon #information-theory #frequency #text #developer-tools
api.oanor.com/entropy-api
Get an API key Try in playground → Contact provider

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

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

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

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
85 ms
Server probes · 24h
Subscribers
3,717
active
Total calls
33
last 7 days
status Full status page → · 18 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 4,335 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 4,335 calls/month
  • 2 req/sec
  • Entropy + frequency
  • No credit card
Sign in to subscribe

Starter

€5.85 /month

  • 13,850 calls / month
  • 8 requests / second
  • Hard cap (429 above quota, no overage)
  • 13.85k calls/month
  • 8 req/sec
  • Char + byte units
  • Email support
Sign in to subscribe

Pro

€25.75 /month

  • 189,500 calls / month
  • 20 requests / second
  • Hard cap (429 above quota, no overage)
  • 189.5k calls/month
  • 20 req/sec
  • Security / compression / NLP pipelines
  • Priority support
Sign in to subscribe

Mega

€63.75 /month

  • 990,000 calls / month
  • 50 requests / second
  • Hard cap (429 above quota, no overage)
  • 990k calls/month
  • 50 req/sec
  • Platform scale
  • Dedicated SLA
Sign in to subscribe

Built by

P
PremiumApi

Related APIs

Other APIs with overlapping tags.

Password API

A fast, fully-local password toolkit: generate cryptographically-secure random passwords (configurable length, character classes and exclude-similar), estimate password strength (entropy bits, a 0-4 score, character-class breakdown, common-password detection, an offline crack-time estimate and actionable feedback), and create memorable diceware-style passphrases. Built on Node crypto, no third-party upstream, and inputs are never logged — so responses are instant, private and always available. Ideal for signup and account flows, admin tools, password managers and security features.

api.oanor.com/password-api

Doppler Effect API

Doppler-effect maths as an API, computed locally and deterministically. The sound endpoint computes the acoustic Doppler shift, f' = f·(v + vo) / (v − vs), where v is the speed of sound (given directly, derived from an air temperature, or the default 343 m/s at 20 °C), vs is the source velocity and vo the observer velocity, with positive velocities meaning approaching: it returns the observed frequency and the frequency shift, and refuses a supersonic source. The light endpoint computes the relativistic Doppler effect for light, f' = f·√((1+β)/(1−β)), from a velocity in metres per second or as a fraction of the speed of light and a direction (approaching blue-shifts, receding red-shifts), returning the frequency and wavelength factor, the observed frequency or wavelength, and the redshift z. The radial-velocity endpoint reverses it: from a measured redshift, or an observed and rest wavelength, it recovers the radial velocity with the exact relativistic relation and the simple v ≈ z·c estimate. Frequencies are in hertz, wavelengths in nanometres, velocities in metres per second. Everything is computed locally and deterministically, so it is instant and private. Ideal for physics and astronomy education, radar, sonar and lidar tools, audio and acoustics apps, and spectroscopy and redshift calculators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the Doppler effect; for sound levels and decibels use an acoustics API.

api.oanor.com/doppler-api

WiFi Channel API

Wi-Fi channel maths as an API, computed locally and deterministically from the standard channel-numbering formulas. The channel endpoint returns the centre frequency of a Wi-Fi channel on the 2.4, 5 or 6 GHz band — the band is auto-detected from the channel number or can be given explicitly (2.4 GHz: 2407 + 5·channel, with channel 14 at 2484; 5 GHz: 5000 + 5·channel; 6 GHz: 5950 + 5·channel). The frequency endpoint does the reverse, returning the nearest channel and band for a centre frequency in MHz or GHz. The overlap endpoint reports whether two channels overlap at a chosen channel width (two channels overlap when their centre-frequency separation is less than the width) and gives the recommended non-overlapping set — the classic 1, 6 and 11 on 2.4 GHz at 20 MHz. Everything is computed locally and deterministically, so it is instant and private. Channel availability is regulated and varies by country. Ideal for networking and Wi-Fi tools, site-survey and IoT apps, and router and access-point configuration software. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is Wi-Fi channel mapping; for general wavelength/frequency and photon energy use a wavelength API.

api.oanor.com/wifichannel-api

Antenna Length API

Antenna length maths as an API, computed locally and deterministically. The dipole endpoint gives the total and per-leg length of a half-wave dipole for a frequency, in metres, feet, inches and centimetres, applying a velocity factor (about 0.95 for wire) and also reporting the classic 468 ÷ f(MHz) feet rule of thumb. The quarterwave endpoint gives the element length of a quarter-wave vertical or monopole, with the 234 ÷ f(MHz) rule. The element endpoint computes the length of an element at any fraction of a wavelength — full-wave, half-wave, quarter-wave, fifth-wave, five-eighths or a custom fraction. Frequencies accept Hz, kHz, MHz and GHz, and the velocity factor is configurable. Everything is computed locally and deterministically, so it is instant and private. These are starting lengths: real antennas need trimming and tuning for the lowest SWR, as end effects and surroundings shift the resonant length. Ideal for amateur-radio and RF tools, antenna and IoT design, and electronics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is antenna geometry; for general wavelength, frequency and photon energy use a wavelength API.

api.oanor.com/antenna-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Entropy API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Entropy API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Entropy 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 Entropy API cost?
Entropy API has a free tier with 100 calls / month. Paid plans start at €5.85 / 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 Entropy API GDPR-compliant?
All requests to Entropy 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/entropy-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/entropy-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/entropy-api/SOME_PATH");
curl_setopt($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/entropy-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.