Readability scores for text
API · /readability-api
Readability API
healthy
3,085 Subscribers
Score how easy a piece of text is to read using the standard, peer-reviewed readability formulas — Flesch Reading Ease, Flesch-Kincaid Grade, Gunning Fog, SMOG, Coleman-Liau and the Automated Readability Index. Pass text and get all six scores back together with the underlying counts (words, sentences, syllables, complex and polysyllabic words, letters and characters), an averaged grade level, an estimated reading time and a plain-English interpretation of the reading ease. A second endpoint counts syllables for a word or for every word in a phrase. Supply text inline via ?text=, as a query parameter or in a request body; everything is computed locally with no network calls, so it is fast and deterministic. Built for content and copywriting tools, SEO and editorial workflows, education and accessibility (plain-language) checks, and UX-writing review. A readability scorer — distinct from sentiment/NLP analysis (nlp), spelling and grammar checking (grammar), the case and text utilities (text) and string similarity (similarity). No upstream key, no cache.
api.oanor.com/readability-api
API health
healthy- Uptime
- 100.00%
- Server probes · 24h
- Avg latency
- 77 ms
- Server probes · 24h
- Subscribers
- 3,085
- active
- Total calls
- 57
- last 7 days
Pricing
Pick a tier — billed monthly, cancel anytime.
Free
Free
- 2,340 calls / month
- 2 requests / second
- Hard cap (429 above quota, no overage)
- 2,340 calls/month
- 2 req/sec
- 6 formulas + counts
- No credit card
Starter
€6.80 /month
- 46,500 calls / month
- 8 requests / second
- Hard cap (429 above quota, no overage)
- 46.5k calls/month
- 8 req/sec
- Reading time + syllables
- Email support
Pro
€21.50 /month
- 238,000 calls / month
- 20 requests / second
- Hard cap (429 above quota, no overage)
- 238k calls/month
- 20 req/sec
- Editorial & SEO pipelines
- Priority support
Mega
€56.80 /month
- 875,000 calls / month
- 50 requests / second
- Hard cap (429 above quota, no overage)
- 875k calls/month
- 50 req/sec
- Content-platform scale
- Dedicated SLA
Built by
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api.oanor.com/fulltextrss-api
Sentiment & NLP API
Analyse text in real time: sentiment scoring (positive / negative / neutral with the matched words), automatic language detection across 180+ languages, and a combined analysis endpoint with text statistics. No setup, no model hosting.
api.oanor.com/nlp-api
Front Matter API
Read and write the front-matter metadata block at the top of Markdown and content files — the --- ... --- header used by Jekyll, Hugo, Astro, Eleventy, Gatsby, Next.js MDX and Obsidian. The parse endpoint splits a document into its structured front-matter data (title, tags, date, draft flags and anything else, as proper JSON), the body content and an optional excerpt, and tells you whether front matter was present. The stringify endpoint does the reverse: give it a JSON object of fields and a body, and it returns a clean Markdown file with a YAML front-matter block. Front matter is read as YAML (which also accepts JSON). Perfect for static-site build steps, headless-CMS imports, content migrations and validating posts. Pure local computation — no key, no third-party service, instant; send large documents via POST. Live, nothing stored. 3 endpoints. Distinct from Markdown rendering / table-of-contents extraction and from YAML/TOML format conversion.
api.oanor.com/frontmatter-api
HTML Sanitizer API
Make untrusted HTML safe to display. Send any HTML — a comment, a rich-text submission, a snippet from an email or a scraped page — and get back a clean, XSS-free version: <script> tags, inline event handlers (onclick, onerror), javascript: URLs, <iframe>, <style> and anything not on the allowlist are removed. Override the allowed tags and attributes to fit your needs, or drop links entirely. A strip endpoint returns plain text with all markup removed. Pure local sanitization — no key, no third-party service, instant. Live. 3 endpoints. Built for user-generated content, comment systems, rich-text editors, email rendering and any place untrusted HTML reaches a browser. Distinct from a Markdown renderer or an HTML data extractor.
api.oanor.com/htmlsanitize-api
Frequently asked questions
Quick answers about pricing, quotas, and integration.
How do I get an API key for Readability API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Readability API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Readability 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 Readability API cost?
Readability API has a free tier with 100 calls / month. Paid plans start at €6.80 / 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 Readability API GDPR-compliant?
All requests to Readability 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/readability-api/SOME_PATH \
-H "x-oanor-key: oanor_test_..."const res = await fetch("https://api.oanor.com/readability-api/SOME_PATH", {
headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();$ch = curl_init("https://api.oanor.com/readability-api/SOME_PATH");
curl_setopt($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/readability-api/SOME_PATH",
headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())Ratings
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