Botoi Readability API vs Eclipse Readability Studio

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.

Eclipse Readability Studio analyzes documents, reports their reading levels, explains readability test results and recommends ways to improve text. It includes grammar checking and offers more than 60 readability tests in English, Spanish and German. Users can analyze a single document or process batches. Supported formats include MS Word, OpenDocument, RTF, HTML, PostScript and text files. The software is free and open source, with versions for Linux, macOS and Windows. The Eclipse project lists its status as Incubating and its license as Eclipse Public License 2.0, while noting that some source code and binaries may have different terms. The project proposal says Readability Studio has provided readability formula and grammar analysis since 2006, and names Blake Madden as project lead and copyright holder. Stated use cases include education, military and government, healthcare, publishing and students. No integrations are stated on the product or project pages.