You wrote your landing page. You checked it in Grammarly. You ran it through Hemingway. You asked ChatGPT to "review it." Three tools, three thumbs up, and your page still converts at 1.2%.
The problem isn't that these tools are bad. They're good at what they do. The problem is that they audit the wrong layer. Grammar tools check correctness. Readability tools check clarity. But neither tells you whether your text will make someone buy.
That's what a copy audit tool does. And in 2026, the category has split into three distinct types, each solving a different problem. This article breaks down what each type covers, where it falls short, and which one fits your workflow.
1. The Three Types of Copy Audit Tools
Before comparing individual tools, you need to understand that "copy audit" means three completely different things depending on who's saying it:
Type 1: Correctness tools. They check grammar, spelling, punctuation, and basic style. Their question: "Is this text error-free?"
Type 2: Readability tools. They check sentence length, complexity, passive voice, and reading level. Their question: "Is this text easy to read?"
Type 3: Conversion tools. They check persuasion structure, cognitive biases, emotional arc, hook quality, and CTA effectiveness. Their question: "Will this text make someone act?"
Most marketers use Type 1 and Type 2 and think they've "audited" their copy. They've checked two layers out of three. The third layer (conversion) is where the money is.
2. Grammar and Spelling Checkers
What they do well: Catch typos, grammar errors, punctuation mistakes, and tone inconsistencies. Essential for any text that faces the public. A landing page with a spelling error in the headline loses credibility instantly.
What they miss: Everything related to persuasion. A grammatically perfect sentence can be completely unpersuasive. "Our comprehensive solution facilitates workflow optimization" has zero errors and zero conversion power.
Main tools:
Grammarly is the industry standard. It catches most grammar and spelling errors, suggests tone adjustments, and now includes AI-powered rewriting suggestions. The free tier covers basics. Premium ($12/month) adds advanced grammar checks, tone detection, and full-sentence rewrites.
The strength: it works everywhere (browser extension, desktop app, integration with most writing tools). The weakness: when Grammarly says your text is "clear and engaging," it means "readable and error-free." It has no framework for evaluating whether the text will convert.
LanguageTool is the open-source alternative. Free tier is generous, premium is cheaper than Grammarly. It supports more languages (30+) and catches different types of errors. Less polished UI, equally useful for correctness checking.
Verdict: Use one of these. They're table stakes, not a competitive advantage. Your copy must be error-free. But error-free is the floor, not the ceiling.
3. Readability and Style Analyzers
What they do well: Flag complex sentences, passive voice, adverb overuse, and jargon. They help you write text that readers can actually process without effort.
What they miss: Readability is not the same as persuasion. A text written at a 6th-grade reading level can still fail to convert if it lacks a hook, proof, or urgency. Simple text that says nothing is still nothing.
Main tools:
Hemingway Editor is the classic. Free web version, $19.99 for the desktop app. It color-codes sentences by complexity, flags passive voice, and gives a readability grade. The interface is clean and the feedback is immediate.
The strength: it forces you to simplify. The weakness: it treats all complexity as bad. Sometimes a longer, more detailed sentence converts better because it carries more proof or specificity. "Our tool analyzes your text" (simple) is less persuasive than "Our tool scores your text on 6 conversion axes, detects 5 cognitive biases, and identifies the exact sentence killing your conversion rate" (complex but specific).
ProWritingAid goes deeper than Hemingway. It checks sentence structure, transition variety, dialogue tags, repeated phrases, and 20+ other stylistic elements. More suited for long-form content than landing pages. Premium starts at $10/month.
Verdict: Use Hemingway for a quick pass on short marketing copy. Use ProWritingAid for blog posts and long-form content. But don't mistake readability for conversion readiness.
4. Conversion and Persuasion Auditors
What they do well: Evaluate whether the text will change the reader's behavior. They analyze the persuasion layer that grammar and readability tools ignore entirely: hook quality, framework structure, cognitive bias activation, emotional arc progression, and CTA effectiveness.
What they miss: They don't check grammar or spelling. They're not writing tools. They're diagnostic tools. You still need a correctness layer.
Main tools:
Copyboost is a psycholinguistic copy audit tool. You paste your marketing text, select the content type (landing page, email, ad), and get a full diagnostic across 6 conversion axes: Hook, Persuasion, Proof and Credibility, Urgency and Desire, CTA and Conversion, and Readability. It also detects which cognitive biases your text triggers (or misses), maps the emotional arc, identifies the persuasion framework (PAS, AIDA, CPPC), and provides a rewritten version with higher-scoring alternatives.
Free plan: 1 full analysis per day across all 7 modules. Pro: 39€/month for 50 analyses/day. Business: 79€/month for unlimited analyses plus PDF export and Schwartz values.
The strength: it's the only tool that scores persuasion structure and cognitive bias activation. The weakness: it doesn't check grammar (pair it with Grammarly).
Anyword takes a prediction approach. It scores copy on predicted performance using historical ad data. Best for paid media teams who need to evaluate ad copy before spending budget. Pricing starts at $39/month.
The strength: performance prediction based on real data. The weakness: optimized for ads and short copy, less useful for landing pages or long-form content.
Unbounce Smart Copy combines AI generation with landing page A/B testing data. Useful if you're already on Unbounce for landing pages. Less useful as a standalone audit tool.
5. AI Writing Assistants as Copy Reviewers
Many marketers paste their copy into ChatGPT or Claude and ask "review my copy." This works, sort of. But with significant limitations.
What they do well: AI assistants can identify obvious structural issues, suggest alternative phrasings, and provide general feedback on tone and clarity. They're versatile and available.
What they miss: They lack a scoring framework. When ChatGPT says "this is good copy," there's no axis definition behind that judgment. You can't compare scores across texts. You can't track improvement over time. The feedback is subjective and varies between sessions.
The core problem: generative AI tools are built to write, not to diagnose. Asking ChatGPT to audit your copy is like asking a novelist to score your essay on a rubric. They can tell you if it "feels" good. They can't tell you it scores 62/100 on persuasion structure and needs anchoring bias in paragraph three.
This is the fundamental difference between a copy audit tool and an AI assistant. The audit tool has a framework. The framework is consistent. The scores are comparable. The diagnostic is actionable.
6. Full Comparison Table
| Capability | Grammarly | Hemingway | ProWritingAid | ChatGPT/Claude | Anyword | Copyboost |
|---|---|---|---|---|---|---|
| Grammar checking | Yes | No | Yes | Partial | No | No |
| Readability scoring | Partial | Yes | Yes | Partial | No | Yes |
| Persuasion structure | No | No | No | Vague | No | Yes |
| Hook quality scoring | No | No | No | Vague | Partial | Yes |
| Cognitive bias detection | No | No | No | No | No | Yes |
| Emotional arc mapping | No | No | No | No | No | Yes |
| Conversion axis scoring | No | No | No | No | Partial | Yes (6 axes) |
| CTA analysis | No | No | No | Vague | Partial | Yes |
| Audience fit testing | No | No | No | No | No | Yes |
| Brand voice analysis | No | Partial | Partial | Partial | No | Yes |
| Performance prediction | No | No | No | No | Yes | No |
| Rewrite suggestions | Yes | No | Yes | Yes | Yes | Yes |
| Free tier | Yes | Yes (web) | Limited | Yes | Limited | Yes (1/day) |
| Price (Pro) | $12/mo | $19.99 (once) | $10/mo | $20/mo | $39/mo | 39€/mo |
| Best for | Correctness | Simplicity | Long-form style | General feedback | Ad copy | Conversion audit |
7. How to Build the Right Stack
You don't need six tools. You need three layers covered:
Layer 1: Correctness (Grammarly or LanguageTool) Catches errors before anyone sees them. Non-negotiable for any published text. Run this first.
Layer 2: Readability (Hemingway) Simplifies dense paragraphs and flags passive voice. Run this second, especially on long-form content. For short copy (headlines, CTAs, emails), you can skip this.
Layer 3: Conversion (Copyboost) Scores the persuasion layer. Run this last, when the text is clean and readable but you need to know if it will convert. This is where most marketers stop too early.
The workflow: Write → Grammarly → Hemingway → Copyboost → Publish.
Three tools. Three layers. Zero blind spots. Total cost: $12/month + $0 + 0€ (free plan) = $12/month. Or use the free tiers of all three for $0.
Start with Layer 3. Audit your copy free on Copyboost.
Frequently Asked Questions
Can't I just use ChatGPT to audit my copy for free?
You can, and it's better than no audit. But ChatGPT gives opinions, not scores. You can't compare two versions objectively, track improvement over time, or identify which specific conversion axis is failing. A dedicated audit tool provides a framework. An AI assistant provides a conversation.
Do I need a conversion audit tool if my copy is already converting well?
Yes. "Converting well" is relative to your current traffic. If you're getting 10,000 visitors and 200 signups (2%), a diagnostic might reveal that your hook scores 90/100 but your proof section scores 40/100. Fixing that one axis could move you to 3%, which is 100 extra signups per month from the same traffic.
How often should I audit my marketing copy?
Before every major launch (new landing page, new campaign, new email sequence). After any significant traffic change. And quarterly for your core pages (homepage, pricing, signup). Think of it like a health checkup for your text.
Is Copyboost only for English text?
Copyboost supports full analysis in English and French. The psycholinguistic framework (persuasion structure, cognitive biases, emotional arc) is language-agnostic, so the core diagnostic applies to any language. Full multi-language support is on the roadmap.
Your Copy Has Three Layers. Most Tools Check One.
Grammar checkers ensure your text is correct. Readability tools ensure it's clear. Neither ensures it converts. The conversion layer (persuasion structure, cognitive biases, emotional arc, CTA effectiveness) is where the revenue sits.
If you only audit one layer, audit the one closest to the money.
Paste your text. Score it on all 6 conversion axes. Free copy audit on Copyboost.
Last updated: May 2026