Analyze Unlimited Text: AI Readability Checkers That Skip Word Limits

If you’ve ever hit a word limit when trying to scan a long draft, you know how maddening it is. Long-form work—essays, research papers, full blog posts—needs tools that treat the entire document as a single unit. Here’s a practical guide to AI readability and detection tools that accept unlimited text and actually produce useful results.

Why word-limit-free detection matters

Many free or lightweight tools cap input size to save processing time and server costs. For casual checks that’s fine, but for editing, grading, or publishing you need the full context. Truncating a document into many small pieces breaks sentence-level and document-level patterns. Advanced detection and rewrite features rely on context to identify tone, coherence, and whether text feels overly 'AI-polished.' If you care about accuracy, skip tools that force you to paste in fragments.

What I tested

I ran several of the most talked-about tools that advertise unlimited input. I focused on three things: how well they handle long documents, the clarity and usefulness of their output, and whether they offer rewriting or improvement options beyond detection.

Originality AI — best for comprehensive, large-scale analysis

Originality AI works well across manuscripts, long-form articles, and website content. It’s built to handle large files without chopping them up.

Core features:

• Unlimited word scanning for both plagiarism and AI detection
• Sentence-level scoring with confidence percentages
• Historical scan records for tracking revisions over time
• Support for DOCX and PDF uploads

Use cases: Ideal for publishers, researchers, and anyone who needs a reliable audit of long submissions.

Undetectable AI — best for refining text after detection

Undetectable AI combines detection with tools to rewrite flagged passages so they read more human without losing meaning.

Core features:

• Full-document scanning with no word limits
• Multiple rewrite styles from academic to conversational
• Keeps original meaning while altering sentence structure
• Built-in grammar and clarity improvements

Use cases: Great for writers who want to sanitize or humanize AI-assisted drafts before publishing.

Phrasly — best for style-first rewrites

Phrasly focuses on producing natural flow during rewrites, which is important when working with long text where consistency matters.

Core features:

• Processes unlimited words in one pass
• Style-specific rewrite modes (creative, formal, casual)
• Side-by-side comparisons to track changes

Use cases: Useful when tone and readability are the main goals, such as marketing copy or essays.

GPTZero — best for quick, no-fuss scans

GPTZero is straightforward and fast, which makes it a good option for educators and anyone needing quick assessments of long texts.

Core features:

• Clean interface that handles large documents
• Highlights sentences likely produced by AI
• Mobile-friendly experience

Use cases: Teachers, editors, and people who need a fast overview rather than deep editing.

Winston AI — best for educator-friendly visuals

Winston AI pairs detection with visual reports that are easy to share and explain.

Core features:

• Unlimited detection with visual 'heat maps' showing likely AI-written sections
• Combined plagiarism and AI scoring
• Secure storage for scanned files

Use cases: Teams and classrooms that benefit from visual feedback and report sharing.

HumanizerPro — best for tone preservation

HumanizerPro aims to adjust AI-written text while keeping the author's voice intact.

Core features:

• Unlimited-length detection and rewriting
• Customizable tone settings
• Minimal structural changes for natural flow

Use cases: Authors who want assistance refining AI-assisted drafts without losing individual voice.

Twixify — best for quick edits on the go

Twixify is light and fast, focused on instant detection and immediate small rewrites.

Core features:

• Unlimited text input with instant detection
• One-click rewrite for flagged passages
• Mobile-first design

Use cases: Quick checkpoints and fast iterations on long documents when you need speed.

Rephracy — best for flexible rewrite options

Rephracy blends detection with a variety of rewrite styles and presets to give more control over final output.

Core features:

• Unlimited detection and rephrasing
• Tone presets for different audiences
• Side-by-side editing interface

Use cases: Teams that need multiple revision passes or want to tailor tone per audience.

Recommendations for different needs

• For high-stakes, long-form work (research papers, client deliverables): Originality AI is the most reliable for comprehensive analysis.
• For humanizing AI-produced text without losing substance: Undetectable AI and HumanizerPro are the best picks.
• For educators or teams needing visual reports: Winston AI stands out for clarity and shareable outputs.
• For quick scans and mobile use: GPTZero and Twixify offer speed and simplicity.

If you regularly work with long documents, the most practical approach is to combine a thorough detector like Originality AI with a refinement tool such as Undetectable AI or Phrasly. That pairing covers detection, context-aware rewriting, and style polishing—everything you need to move a long draft from raw to ready.