The best free readability checker — scores content with 7 formulas, checks AI crawler accessibility across GPTBot, ClaudeBot and PerplexityBot, and flags hard paragraphs with fix suggestions.
Paste a URL or text. It scores readability with 7 formulas, checks AI crawler accessibility, and shows exactly which paragraphs need work.
Scores use 7 formulas (Flesch, Gunning Fog, SMOG, Coleman-Liau, ARI, Linsear Write) with a weighted consensus grade. AI Citation Readiness checks whether your content structure is optimised for GPTBot, ClaudeBot and PerplexityBot. Up to 10 URLs per run.
uploaded over TLS · deleted within one hour
Notes from other visitors. Sign in with Google to add yours, or send a private suggestion straight to the developer.
Sign in to leave a comment. We only use Google — no passwords, no email spam.
Sign in with GoogleNo comments yet. Be the first.
Enter up to 10 URLs to check, or paste text directly. The tool fetches the page as 5 different crawlers — Chrome, Googlebot, GPTBot, ClaudeBot and PerplexityBot — so you see exactly what each one sees.
Readability Score uses 7 standard formulas with a weighted consensus grade. Content Clarity measures passive voice, sentence length and complex word density. AI Citation Readiness checks whether your content structure is optimised for AI search engines to cite.
The per-paragraph heatmap scores every paragraph individually and colour-codes it green (easy), yellow (moderate) or red (difficult). Click any paragraph to expand the full text and see exactly which sentences need work.
Every issue carries a rule ID, severity level, evidence snippet and a fix suggestion classified as deterministic (copy-paste safe), safe-with-review, or semantic (requires human judgment). Share the report with your writer via a 48-hour link.
We ran the same files through the popular alternatives first. These are the gaps we found, and what this tool does instead.
We run all 7 standard readability formulas (Flesch Reading Ease, Flesch-Kincaid Grade, Gunning Fog, SMOG, Coleman-Liau, ARI, Linsear Write) and synthesise a single weighted consensus grade with outlier dampening. Then we score every paragraph individually and show a colour-coded heatmap so you know exactly where to rewrite.
We fetch your URL as 5 different user agents — Chrome Desktop, Googlebot, GPTBot (ChatGPT), ClaudeBot (Claude) and PerplexityBot — and compare the content each one receives. If any AI crawler is blocked or sees different content, we flag it with the specific crawler name and word count difference.
Our AI Citation Readiness score (beta) checks five structural factors: keyword overlap between H1 and first paragraph (inverted pyramid), topic sentence strength, question-format heading density, structured content signals (headings, lists, tables) and AI crawler accessibility. It tells you not just "is this readable" but "will AI search engines cite this."
Most free tools run 1-3 readability formulas. We run all 7 standard formulas and synthesise a single consensus grade using weighted averaging with outlier dampening. If one formula disagrees with the median by 3+ grades (common with jargon-heavy but short-sentence text), its weight is halved. The result is a more stable, defensible grade level than any single formula provides. Each formula's individual score is still visible in the breakdown.
We fetch your URL as Chrome Desktop, Googlebot, GPTBot (ChatGPT), ClaudeBot (Claude) and PerplexityBot — the same crawlers that determine whether your content appears in AI search results. If any AI crawler sees significantly fewer words than Chrome (below 50% word count), we flag it as content cloaking. If a crawler is blocked entirely, we report which one and why. A readability score is meaningless if the content isn't reachable.
Instead of a single document-wide score, we grade every paragraph individually using Flesch-Kincaid and colour-code it green (Grade 8 or below), yellow (Grade 9-12) or red (Grade 13+). Writers can scan the heatmap, click the red paragraphs, and see exactly which sentences contain too many complex words or run too long. Each flagged paragraph carries its own issue with a fix suggestion.
Beyond traditional readability, we score five structural factors that correlate with AI search citation: keyword overlap between your H1 and first paragraph (inverted pyramid), topic sentence strength (short declarative openers), question-format heading density (matching People Also Ask patterns), structured content signals (headings, lists, tables) and AI crawler accessibility. The score is calibrated against real AI-cited content and will improve as we gather more data.
Our Content Clarity score breaks writing quality into five measurable sub-scores: passive voice percentage, average sentence length, complex word density (3+ syllables), adverb density and paragraph length consistency. When complex word density is high, we suggest specific simpler alternatives from a curated substitution list — "utilize → use", "methodology → method", "facilitate → help". Every suggestion is flagged as safe-with-review so writers can accept or reject with confidence.
Eliminating Formula Variance: How Outlier Dampening Prevents Jargon Distortions Standard reading formulas (like Gunning Fog or SMOG) weigh text difficulty by running rigid mathematical calculations on sentence duration and syllable-to-character distribution matrices. While accurate for standard narrative prose, these models falter when analyzing modern technical writing, software documentation, or digital marketing material. Short, punchy sentences containing hyper-specific keyword entities (e.g., “API execution loop”) can cause individual formulas to spike incorrectly by up to five grade levels. To resolve this variance, the ToolsVale engine runs an advanced Outlier Dampening Filter at compilation. If any individual reading score deviates from the document’s median index line by more than three full grade brackets, its mathematical weight in the final calculation loop is immediately slashed by 50%. This prevents niche trade terms from artificially distorting your content’s consensus grade, providing an incredibly stable, defensible framework for scaling copy parameters.
Detecting Agentic Cloaking: Ensuring Text Parity Across Search and AI CrawlersA rising problem in modern technical SEO is server configuration asymmetry. Due to overly aggressive firewall settings or misconfigured content delivery network (CDN) edge rules, web servers often pass clean HTML text arrays to standard user-agent browsers (like Chrome Desktop) while delivering empty containers or firewall challenges to AI scrapers. This state is known as Agentic Cloaking. If a CDN presents a 403 Forbidden challenge block to an automated agent, your page content becomes completely invisible to that model’s discovery index. Our AI Readability framework tests against this threat by firing five parallel request paths on every URL run. By systematically comparing the exact text strings returned to Chrome, Googlebot, GPTBot, ClaudeBot, and PerplexityBot, our system measures word count delta variations in real time [1.16]. If an AI crawler returns under 50% of the visible copy found by Chrome, the panel triggers an immediate Content Cloaking Anomaly Warning, saving your digital footprint before your content gets dropped from AI search summaries
Last reviewed August 2026 · this tool runs server.
A readability checker analyses text and produces a score estimating how easy it is to read. It uses mathematical formulas that count sentence length, word complexity (syllable count or character count) and other structural features, then maps the result to a US grade level or a 0-100 scale. The score tells you the minimum education level a reader needs to understand your content comfortably. For web content, a Grade 8-9 target reaches the broadest audience.
Three things no other free tool combines. First, we run all 7 standard readability formulas with a weighted consensus grade instead of relying on a single formula. Second, we check whether AI crawlers (GPTBot, ClaudeBot, PerplexityBot) can even see your content — a readability score is useless if the page is blocked. Third, we score every paragraph individually and show a colour-coded heatmap so you fix the specific paragraphs that need work, not the whole document.
WebFX runs 6 formulas (we run 7) but gives you 6 separate numbers with no consensus grade. It doesn't check AI crawler accessibility, doesn't score paragraphs individually, doesn't offer fix suggestions with safety tiers, doesn't detect content cloaking and doesn't provide shareable report links. Both tools are free and support URL input. We also support multi-URL bulk comparison (up to 10 URLs), which WebFX doesn't offer.
SEO Review Tools runs a single formula — Flesch Reading Ease — and requires an account after a few uses. We run 7 formulas with consensus grading, check AI crawler accessibility across 5 user agents, provide per-paragraph analysis, offer fix suggestions with safety tiers, support multi-URL comparison and provide 48-hour shareable report links. No account required, ever.
Seven standard formulas: Flesch Reading Ease (0-100 score, higher is easier), Flesch-Kincaid Grade Level (US grade), Gunning Fog Index (years of education needed), SMOG Index (polysyllabic word count), Coleman-Liau Index (character-based, no syllable counting), Automated Readability Index (character-based) and Linsear Write Formula. Each uses different inputs, so disagreement between them is useful diagnostic information.
AI Citation Readiness (beta) measures how likely AI search engines are to cite your content. It checks five structural factors: whether your first paragraph directly answers your H1 question (inverted pyramid), whether paragraph openers are short declarative sentences (topic sentence strength), whether headings use question format (matching People Also Ask patterns), whether content includes headings, lists and tables (structured signals), and whether AI crawlers can access the page. The score is calibrated against real AI-cited content.
In 2026, AI search engines like ChatGPT (GPTBot), Claude (ClaudeBot) and Perplexity (PerplexityBot) drive significant traffic. If your robots.txt blocks these crawlers or your CDN serves them different content, they cannot cite your page in AI-generated answers — regardless of how readable your content is. Our tool fetches your URL as all 5 crawlers and compares what each one receives.
Yes. Paste up to 10 URLs per run and get a side-by-side comparison table showing all 3 scores for each URL, sorted by any column. Click any row to expand the full detail. This is useful for auditing a site section or benchmarking your content against competitor pages. You can share the entire comparison as a single 48-hour link.
No. The tool is completely free, requires no account, has no daily limit, adds no watermark and doesn't gate any features behind a paywall. The rate limit is 30 checks per minute per IP, which protects the server without restricting normal use.
Our server fetches raw HTML, so content injected by JavaScript (React, Vue, Next.js client-side rendering) may not be visible. If we detect fewer than 100 words with no headings and no paragraph tags, we flag the page as potentially JS-rendered and suggest using the Text Input tab for accurate scoring. For JS-heavy sites, paste the visible page text directly.
Analyze meta tags, preview SERP and social cards, detect cloaking, and generate optimized meta tag code — for up to 10 URLs at once.
The best free schema validator — checks JSON-LD, Microdata, and RDFa against schema.org v30 and Google's 2026 rules, plus content parity and AI-crawler visibility.
Free SEO + AEO audit with 5-crawler cloaking detection, AI citation scoring, and Core Web Vitals. No signup.
