Botoi Readability API vs Data·yze Readability Analyzer

Botoi Readability API analyzes English text and returns Flesch-Kincaid Grade, Flesch Reading Ease, Gunning Fog, and underlying counts. A request sends a required text string to POST /v1/text/readability and receives JSON. Flesch Reading Ease scores run from 0 to 100, with higher values indicating easier reading; Gunning Fog estimates the years of formal education needed. The formulas and syllable heuristics are calibrated for English, so grade mapping is not meaningful for other languages. Botoi recommends sending at least 100 words because short samples can produce unstable scores. Suggested uses include enforcing plain-language standards, reviewing legal or medical drafts, refining blog posts for SEO, and comparing writing across authors. Examples are provided in cURL, JavaScript, TypeScript, Python, and Go. The Free plan is free and lists 1,000 requests per day and 10 per minute; the endpoint page separately states five requests per minute for its free tier. Starter costs $9 a month. Requests above a per-minute or daily cap receive HTTP 429, and daily limits reset at midnight UTC.

Data·yze Readability Analyzer is a free, ad-supported web app that estimates how readable text may be for a chosen audience. It reports Flesch-Kincaid Reading Ease, Gunning Fog Index, Kincaid Grade Level, SMOG, Dale–Chall, and Fry Reading Graph metrics. Sentence analysis and clarity recommendations are available, while a paragraph view shows statistics and changes in readability through a document. You can enter text or upload a file, then save or download the input. A separate Website Readability Analyzer evaluates an individual webpage and average readability across a site. Its crawler is limited to 1,000 pages per user per day; pausing and resuming on another day can work around that cap. Data·yze says analyzed passages are not collected or stored, although passage length is retained for performance analysis. Uploaded files may be cached and automatically removed within seven days, possibly sooner. The maker cautions that scores are heuristic estimates, not writing-quality measures, and work best with plain text.