Top 10 AEO Audit Tools for 2026: Complete Technical Comparison

Stobo ranks #1 among AEO audit tools with a perfect 100/100 score. It is the only tool achieving A grades across all 7 technical checks. Competitors average 3-4 checks at best. The difference: Stobo provides implementation code, not just diagnosis. One-time €199 versus $29-489/month subscriptions.

Before building our AEO audit tool, we ran every competitor's website through the same checks we recommend to clients. The results were clear. Most AEO tool providers don't implement what they preach.

Here's what we found, how we ranked them, and what it means for your AEO strategy.

The complete ranking

We scored each tool on 7 AEO factors, ordered by citation impact. The methodology section below explains why this order matters.

Rank	Tool	Score	Key Strength	Gap	Pricing
1	Stobo	100/A	7/7 checks + implementation code	No content monitoring	€0-199 once
2	Otterly.AI	64/C	Content quality scoring	Binary technical checks	$29-489/mo
3	HubSpot AEO Grader	~70/C	Free unlimited reports	No fixes or code	Free
4	Frase.io	~55/D	Real-time GEO scoring	Limited schema depth	$45+/mo
5	Agenxus	~60/D	Schema validation	No llms.txt, no freshness	Contact
6	BetterAEO	7/E	Free Chrome extension	Poor self-implementation	Contact
7	SEMrush AI Toolkit	~50/D	SEO suite integration	Add-on only	$99+/mo
8	AEO Audit Tool	46/D	Simple interface	Limited checks	Contact
9	SEMAI.ai	~55/D	Multi-language support	No implementation	Contact
10	Writesonic GEO	~45/D	All-in-one platform	Broad focus dilutes depth	$16+/mo

The gap between first and second place is significant. Stobo scores A across all 7 factors. The next closest competitor scores A on 4 factors at best. Most score A on just 1 or 2. For detailed methodology, see How the Stobo Score Works.

Why this order matters: the 7 AEO factors ranked by impact

Not all AEO factors carry equal weight. Research from Princeton's GEO study, Yext's 6.8 million citation analysis, and our own testing across 200+ pages reveals a clear hierarchy.

High impact (implement first)

1. FAQ schema markup

FAQ-optimized content achieves 41% AI citation rates versus 15% for unstructured content. That's a 2.7x advantage from structure alone.

The Princeton GEO study found that 78% of AI-generated answers include list formats. FAQ structure matches how AI systems naturally organize responses. When your content already exists as question-answer pairs with proper FAQPage schema, AI systems can extract it directly without interpretation.

Most tools check whether FAQ content exists. Stobo is the only tool that verifies FAQ content is paired with FAQPage schema on the same page. Unpaired FAQs are invisible to AI systems. We catch that gap.

2. Direct answer optimization

The first 40-60 words of any page determine citation likelihood. AI systems heavily weight opening paragraphs when deciding whether to cite a source.

The same Princeton study found that content with direct answer formatting receives 67% more citations. This length provides enough context for complete responses without being so long that AI systems truncate or summarize incorrectly.

We analyze whether your intro directly answers the implicit question users are asking. Most competitors skip this check entirely.

3. robots.txt configuration

If AI crawlers are blocked, nothing else matters. Your content quality becomes irrelevant.

AI crawler traffic grew 305% between May 2024 and May 2025, according to Cloudflare data. GPTBot alone accounts for 30% of all AI crawler activity. The crawl-to-referral ratios tell the story: 38,000:1 for Anthropic's Claude, 1,091:1 for OpenAI's ChatGPT. These systems crawl aggressively.

Most tools check whether robots.txt blocks "AI crawlers" as a binary pass/fail. That misses the point. Different crawlers serve different purposes. GPTBot trains models while ChatGPT-User fetches pages in real-time for browsing users. Blocking one has different consequences than blocking the other.

Stobo checks 21 specific AI crawlers individually. When ChatGPT-User is blocked but GPTBot is allowed, you get included in training data but not in real-time browsing results. Users ask ChatGPT a question, ChatGPT tries to fetch your page, gets blocked, moves on to a competitor. That distinction matters.

4. Schema markup diversity

Research shows 61% of pages cited by AI use three or more schema types. Having schema on your homepage alone is not enough.

Fabrice Canel confirmed at SMX Munich 2025: "Schema markup helps Microsoft's LLMs understand your content." Google's John Mueller stated "we currently prefer JSON-LD markup" for structured data implementation.

We analyze schema type diversity and distribution across your pages. A site with Organization, FAQPage, and Product schema distributed across relevant pages outperforms a site with only Organization schema on the homepage.

5. Sitemap completeness

AI crawlers need efficient page discovery. A missing or incomplete sitemap creates a discovery barrier, especially for sites without JavaScript execution capabilities.

This is table stakes. Most tools check it. We include it for completeness.

Medium impact

6. Content freshness

Pages not updated quarterly are 3x more likely to lose AI citations. Over 70% of all cited pages have been updated within 12 months.

Freshness signals tell AI systems that your content reflects current reality. Stale content gets deprioritized. We check last-modified signals and flag pages that may be losing citations due to age.

Future-proofing (low current impact)

7. llms.txt analysis

Over 844,000 websites have implemented llms.txt, including Anthropic, Cloudflare, and Stripe. The standard is gaining adoption.

However, we need to be honest: no major AI crawlers currently check for this file. John Mueller noted that "AFAIK, none of the AI services have said they're using LLMs.TXT."

We include this check because the standard will likely matter within 12-18 months. Think of it as preparing for where AI systems are heading, not where they are today. A file can exist but still be poorly structured. We analyze 7 sub-components including title quality, description completeness, contact info, resource organization, link format preferences, categorization structure, and context optimization.

Most tools offer a binary check: file exists or doesn't. We provide quality analysis for when this standard becomes operational.

The implementation gap

Here's what the competitive analysis revealed: most AEO tools monitor. Few help you implement.

Yext's research of 6.8 million AI citations found that 86% come from brand-managed sources. First-party websites alone generate 44% of all citations. Listings and directories account for 42%. Reviews and social add another 8%.

"When brands control their data, they control their visibility," said Mike Walrath, CEO of Yext.

The implication is clear. Technical foundation matters more than most realize. AI systems cite your website, your schema markup, your structured content. The citations come from infrastructure you own and can optimize.

Yet 90% of sites we audit need implementation help, not just diagnosis. They know something is wrong. They need the fix.

This is where most tools stop. They tell you the problem. They don't tell you how to solve it.

Stobo's Premium report includes copy-paste implementation code. JSON-LD schema blocks ready to deploy. robots.txt rules formatted for your server. A complete llms.txt file generated from your site content. The difference between knowing you need FAQ schema and having the code to add it.

The cost difference over two years tells the story:

Tool	Free Tier	Entry	Mid	Top	2-Year Cost
Stobo	Full 7-check audit	€0	€199	€199	€0-199
Otterly	14-day trial	$29/mo	$189/mo	$489/mo	$696-11,736
HubSpot	Unlimited	Free	Free	Free	$0
Frase	Limited	$45/mo	$114/mo	$114/mo	$1,080-2,736
SEMrush	None (add-on)	$99/mo	$99/mo	$99/mo	$2,376+

Technical foundation is fix-it-once work. You don't need to check your robots.txt every month after you've fixed it.

Feature comparison by impact

Here's how each tool performs on the factors that matter most, ordered by citation impact:

Feature	Stobo	Otterly	HubSpot	Frase	BetterAEO
FAQ-schema pairing	Yes (unique)	No	No	No	No
Direct answer check	40-60 word analysis	No	No	No	No
robots.txt depth	21 crawlers	Pass/fail	Basic	Basic	Basic
Schema diversity	Type + distribution	Exists/not	Basic	Partial	Partial
Freshness signals	Yes	No	No	No	No
llms.txt analysis	7 factors	Exists/not	No	No	No
Implementation code	Yes (Premium)	No	No	No	No
Free tier	Full audit	14-day trial	Yes	Limited	Chrome ext
Pricing model	One-time	Monthly	Free	Monthly	Contact

The pattern is clear. Stobo covers high-impact factors that competitors skip. The trade-off: we don't offer ongoing monitoring. Different problems require different tools.

Individual tool analysis

#1 Stobo (100/100)

The only tool scoring A across all 7 AEO factors. We built it, so we'll let the data speak.

What makes it different:

We check FAQ-schema pairing. No competitor does this. FAQ content without FAQPage schema is invisible to AI systems. The 2.7x citation advantage only applies when content and schema are paired on the same page.

We analyze 21 AI crawlers individually, not as a binary pass/fail. When ChatGPT-User is blocked but GPTBot is allowed, you get trained on but not cited in real-time. That distinction changes your strategy.

We score 7 llms.txt sub-components. A file can exist but still be poorly structured. We prepare you for when this standard becomes operational.

Premium includes implementation code. Not just diagnosis. The actual fix.

Pricing: Free audit with unlimited runs. €199 one-time for Premium with implementation code.

Best for: Fixing technical foundation. Deploy once, done.

#2 Otterly.AI (64/100)

Over 15,000 users. Recognized by Gartner as a Cool Vendor. They built something real.

What they do well:

Content quality scoring. They count quotes, statistics, and measure conversational tone on every page. The Princeton GEO study found that adding statistics improves visibility by up to 40%. Otterly actually counts your statistics.

Ongoing monitoring. They track brand mentions across ChatGPT, Perplexity, Google AI, and other platforms over time. You can watch visibility change week to week.

Clean interface. Well-designed tool with clear audit results.

Where they fall short:

Binary technical checks. Their robots.txt check says blocked or not blocked. Their llms.txt check says exists or doesn't. That misses the nuance that determines citation outcomes.

No FAQ-schema pairing. They check if FAQ content exists. They don't verify it's paired with proper markup.

No implementation code. Diagnosis without the cure.

Pricing: $29-489/month depending on prompt volume. Lite gets 1,000 URL audits and 15 search prompts. Premium gets 10,000 audits and 400 prompts.

Best for: Ongoing content monitoring after technical foundation is solid.

#3 HubSpot AEO Grader (~70/100)

Completely free with unlimited reports. A strategic move to drive marketing platform adoption.

What they do well:

No cost barrier. Run as many reports as you want without paying.

Runs actual AI queries. They check how AI systems currently respond to prompts about your brand. Real visibility data, not just technical analysis.

Brand sentiment analysis. Competitive positioning insights you won't get from technical audits alone.

Where they fall short:

No implementation guidance. They tell you there's a problem. They don't tell you how to fix it.

No code generation. You still need to figure out the technical implementation yourself.

Limited technical depth. Good for quick assessment, not comprehensive optimization.

Pricing: Free.

Best for: Quick baseline check before investing in deeper tools.

#4 Frase.io (~55/100)

Real-time GEO scoring inside a content editor. Different approach than pure audit tools.

What they do well:

Live scoring while you write. See how changes affect your GEO score in real time.

No signup required for the free GEO Score Checker. Low friction to try it. Content-first workflow. Built for writers, not just technical SEOs.

Where they fall short:

Limited schema analysis. They check structure but don't verify FAQ-schema pairing. No implementation code. Still need to handle technical fixes separately.

Pricing: $45/month for full features.

Best for: Content optimization workflow. Writers who want feedback as they create.

#5 BetterAEO (7/100)

Free Chrome extension for quick audits. Claims 30+ ranking factors.

The credibility problem:

Their own website scores 7/100 on AEO. They don't practice what they preach.

We ran every competitor through our audit. BetterAEO had the lowest score of any tool provider. If they can't optimize their own site, their recommendations deserve scrutiny.

Pricing: Free Chrome extension. Contact for additional services.

Best for: Quick browser-based checks only. Take recommendations with caution.

When to use each tool

Use Stobo when you need to fix technical foundation. AI crawlers are blocked, schema is missing, FAQ content lacks markup. Fix once, no recurring cost.

Use Otterly when technical foundation is solid and you want to track content quality and brand mentions over time. Worth the subscription for ongoing monitoring.

Use HubSpot when you want a free baseline check before investing in tools. Good starting point to understand where you stand.

Use Frase when you're creating content and want real-time GEO scoring as you write. Useful for content teams, less useful for technical optimization.

Use both Stobo + Otterly when you want comprehensive coverage. Stobo first (€199 once) to fix foundation, then Otterly ($29+/mo) to optimize content and track results. Different phases of the same optimization process.

What competitors do better than us

Credit where it's due.

Otterly measures content quality signals we don't. Their quote count, statistics count, and natural language scoring identifies content gaps. The Princeton study confirms these signals affect citations. If you want to improve how your content reads to AI systems, Otterly provides data we don't.

HubSpot is completely free. No trial period, no feature limits, unlimited reports. If budget is zero, start there.

Frase offers real-time scoring in the content editor. Writers see feedback as they create. That workflow integration is something audit tools don't provide.

Otterly also has ongoing monitoring. They track your brand mentions across AI platforms over time. We don't offer monitoring. Our model is fix-it-once, not track-it-forever.

What we do better than them

Our turn.

Technical depth on robots.txt. 21 crawlers checked individually versus binary pass/fail. The distinction between GPTBot and ChatGPT-User determines whether you're trained on or cited in real-time.

llms.txt quality analysis. Seven sub-components scored versus "file exists." Title quality, description completeness, contact info, resource organization, link format preferences, categorization structure, context optimization. Plus we generate the file for you in Premium.

FAQ-schema pairing. The only tool that verifies FAQ content has matching FAQPage schema on the same page. This is where the 2.7x citation advantage comes from. Unpaired FAQs don't get that boost.

Direct answer optimization. We check if your first paragraph is 40-60 words with clear value proposition. 67% more citations for optimized openings. Most tools skip this entirely.

Freshness signals. Pages not updated quarterly are 3x more likely to lose citations. We flag stale content. Competitors don't track this.

Implementation code. The actual fix, not just the diagnosis. JSON-LD blocks, robots.txt rules, complete llms.txt files. Copy, paste, deploy.

One-time pricing. Fix technical foundation once. No recurring monthly fees. €199, done.

The market context

The AEO market is projected to grow from $848 million in 2025 to $33.68 billion by 2034 at 50.5% CAGR, according to Dimension Market Research. Over $77 million in funding flowed to AI visibility startups in 2025 alone.

ChatGPT now processes 400 million queries weekly. AI Overviews appear in 51% of search results. ChatGPT referral traffic has increased 145x since mid-2024. Over 50% of U.S. consumers use AI assistants weekly.

72% of marketing leaders believe AI search will have a bigger impact on customer acquisition than traditional SEO within three years. Yet 64% are unsure how to measure success. The gap between adoption and understanding creates opportunity.

"AI generates answers based on a person's real-world location and context, not a generic brand view," said Christian J. Ward, Chief Data Officer at Yext.

The Graphite CEO put it simply: "Early-stage startups can win at AEO when they couldn't at SEO."

Research from Princeton found that lower-ranked websites benefit most from AEO optimization. Sites ranking fifth in traditional search saw 115% visibility increases from proper implementation. The technical foundation advantage is real.

The bottom line

We audited every AEO tool provider. Most don't practice what they preach. Stobo scores A across all 7 factors. The next closest competitor scores A on 4. Most score A on 1 or 2.

The differentiation is simple. We check FAQ-schema pairing. We analyze 21 AI crawlers individually. We measure direct answer optimization. We track freshness signals. We provide implementation code.

They tell you the problem. We tell you how to fix it.

Run the audit yourself. trystobo.com is free. See how your site compares.

For deeper comparisons with specific competitors, see:

• Stobo vs Otterly.ai
• Stobo vs AI Rank Lab
• Stobo vs BotRank

To understand the technical foundation of AEO, start with our comprehensive implementation guide.

Last updated: January 9, 2026

Methodology: We ran each competitor's website through the same 7-factor AEO audit we offer to clients. Scores reflect actual implementation, not marketing claims. Research sources linked throughout.