By the end of this comparison you will know exactly what each free tool measures, where each one is weaker, what it costs to go beyond the free check, and which one a Hong Kong enterprise should run first. Both tools are free. The decision is not about price; it is about which question you need answered.
The two tools most often shortlisted by Hong Kong marketing and digital teams for a first Answer Engine Optimization (AEO) check are UD's AEO Auditor and HubSpot's AI Search Grader. They look similar on a landing page. They measure almost entirely different things.
What do UD AEO Auditor and HubSpot AI Search Grader actually measure?
UD AEO Auditor scans your website's structure, running 170+ checks on schema, crawler access, headings and citations, then scores how readable and quotable your site is for five AI engines. HubSpot AI Search Grader asks three AI models how they perceive your brand and scores sentiment, recognition and share of voice out of 100.
UD AEO Auditor is a site-level diagnostic. You enter a URL, and within about 30 seconds it returns an AI Visibility Score against a 172-point standards checklist, an AI Copy Signals module that judges whether your copy is conversational and cites sources, 11 numeric structure checks, and a prioritised action plan. According to its landing page, it has analysed 46,006 sites and covers ChatGPT, Google AI Overview, Perplexity, Claude and Gemini.
HubSpot AI Search Grader is a brand-perception diagnostic. You enter a company name, location, product and industry, not a URL. The tool queries GPT-5.4 mini, Perplexity and Gemini about how they characterise your brand and returns a composite score out of 100 across five weighted dimensions: sentiment (40 points), presence quality (20), brand recognition (20), share of voice (10) and market competition (10).
Put simply, UD answers "why can't AI read and cite my website?" while HubSpot answers "what does AI currently believe about my brand?" An enterprise usually needs both answers, but rarely at the same moment.
How do the two tools compare on the criteria that matter to an enterprise buyer?
On price both are free. UD covers five engines to HubSpot's three, needs a URL rather than a brand description, and produces a technical fix list. HubSpot produces a perception score with written interpretation, accepts competitor brands, and upsells to a US$50 per month monitoring product. Neither offers API, SSO or enterprise exports on the free tier.
Side-by-side facts (verified 24 September 2026)
--- Price of the check: UD AEO Auditor HK$0, no credit card, no account. HubSpot AI Search Grader US$0, no account required, short form to unlock full results.
--- Input required: UD needs a website URL. HubSpot needs company name, location, product or service, and industry.
--- AI engines covered: UD reports on ChatGPT, Google AI Overview, Perplexity, Claude and Gemini (five). HubSpot cross-validates GPT-5.4 mini, Perplexity and Gemini (three).
--- What is scored: UD scores site structure against 172 AEO standards plus copy signals. HubSpot scores brand perception out of 100 across five dimensions.
--- Time to result: UD states under 30 seconds for most sites, up to 60 for complex ones. HubSpot states under two minutes.
--- Output: UD returns an interactive dashboard and prioritised action plan on the page. HubSpot returns a composite score, breakdown and written interpretation.
--- Competitor analysis: UD provides peer comparison and industry ranking. HubSpot accepts any brand name, so you can grade competitors directly.
--- Language and locale: UD's interface is available in English, Traditional Chinese, Simplified Chinese, French, Spanish, Japanese and Korean. HubSpot's is available in English, French, German, Spanish, Portuguese and Japanese.
--- Paid next step: UD offers quote-based AEO, SEO and GEO consulting from its Hong Kong team. HubSpot offers HubSpot AEO monitoring at US$50 per month, also included in Marketing Hub Professional and Enterprise, with a free trial.
--- Not available on either free tier: API access, SSO, scheduled exports, contractual SLA.
If you want the wider price landscape for paid AEO platforms, our Answer Engine Optimization pricing guide for Hong Kong enterprises covers the monitoring tier in detail.
Where does HubSpot AI Search Grader win?
HubSpot wins when the question is brand perception. Its sentiment-weighted score, competitor grading and written interpretation give a CMO a boardroom-ready snapshot of how AI describes the company. Its US$50 per month monitoring product is also the cheaper, more transparent route to week-over-week tracking than a bespoke consulting engagement.
Sentiment and positioning. Forty of HubSpot's 100 points are sentiment, split into general, contextual and source-based layers. If your concern is that AI assistants describe your firm as a niche player or attach negative service commentary, HubSpot surfaces that directly. UD does not attempt a sentiment score.
Competitive intelligence without their URL. Because HubSpot works from a brand description, you can grade a competitor in two minutes without touching their website. Useful before a pitch or a board paper.
Transparent recurring price. HubSpot AEO at US$50 per month is a published, self-serve price with a free trial and no HubSpot subscription required. For a team that wants a time series rather than a one-off audit, that is a defensible line item. UD's execution work is quote-based, which is right for a bespoke programme but harder to benchmark.
Global brand data. HubSpot's approach works well for internationally known brands with rich training-data footprints. For those companies the perception score is meaningful.
Where does UD AEO Auditor win?
UD wins when the question is fixability. It scans the actual website, returns 170+ specific structural findings such as missing JSON-LD or weak internal linking, and ranks fixes by priority. It covers five engines including Google AI Overview and Claude, offers a Traditional and Simplified Chinese interface, and connects the report to a Hong Kong-based team that can implement the changes.
Actionable technical findings. A perception score tells you AI does not recommend you. It does not tell you that your schema markup fails on 8 of 13 checks or that your H1 hierarchy is inconsistent. UD's structure checks, covering JSON-LD coverage, canonical URLs, robots.txt, sitemap, alt text, internal linking and citation density, translate directly into tickets for a web team.
Five engines, including the two that matter most in Hong Kong search. Google AI Overview is the AI surface most Hong Kong customers see first because it sits inside Google Search, and Claude is increasingly used inside enterprise tooling. Neither is in HubSpot's three-engine set.
Chinese-language readiness. Most Hong Kong enterprise sites run bilingual or trilingual content. UD's interface and report are available in Traditional and Simplified Chinese, and the tool is built by a Hong Kong company that has operated since 1998. For a brand with a thin English footprint, a perception-based grader may return little; a structure-based scan still returns a full fix list.
Zero-friction start. No sign-up, no card, results on the page. An email is requested only to view the full dashboard and for optional follow-up. For a Head of Digital Transformation who wants a baseline before the next steering committee, that matters.
What does each tool cost beyond the free check?
Beyond the free scan, HubSpot's path is HubSpot AEO at US$50 per month, or inclusion in Marketing Hub Professional and Enterprise, with a free trial. UD's path is a consulting engagement covering AEO structure, SEO ranking and GEO visibility, priced by quotation after a scan review. Neither free tool has hidden charges or auto-billing.
HubSpot. The Grader itself is free and one-time. The published next step is HubSpot AEO, listed at US$50 per month on the Grader page, with monitoring across ChatGPT, Perplexity and Gemini, competitor comparison and prioritised recommendations. It is also bundled into Marketing Hub Professional and Enterprise, so existing HubSpot customers at those tiers may already have it.
UD. The scan is free and can be re-run monthly, which the tool itself recommends because structural changes are typically re-crawled within two to four weeks and citation changes within one to three months. Implementation is a consulting engagement scoped after the scan: an AEO specialist walks through each finding and maps an execution plan. Pricing is by quotation, so budget it as a project rather than a subscription.
Total-cost framing for a 200-person firm. A team that only wants to know whether perception is improving can run HubSpot AEO for roughly US$600 a year. A team whose site fails a majority of structure checks will need implementation work regardless of which monitoring tool it picks, and that implementation, not the monitoring, is where the budget goes. For alternatives at the monitoring tier, see our review of Profound alternatives for Hong Kong enterprises.
What are the limitations of each tool?
UD AEO Auditor has no API, SSO or scheduled export, does not score brand sentiment, and its paid execution is quote-based rather than published. HubSpot AI Search Grader scans brand perception from training data rather than your live site, covers only three engines, cannot tell you what to fix technically, and requires a form to unlock full results.
UD AEO Auditor limitations
--- No API access, SSO or scheduled exports on the free tool, so it does not slot into an enterprise reporting stack without manual steps.
--- No brand-sentiment or share-of-voice score. It tells you whether AI can read you, not how AI feels about you.
--- Execution pricing is by quotation. Enterprises that need a published per-seat or per-month figure for procurement will have to ask.
--- The free report requests an email to display the full dashboard, which some procurement teams treat as a lead-capture step.
HubSpot AI Search Grader limitations
--- It grades what three models believe from training data at the time of the check. It does not crawl your website, so it cannot identify structural fixes.
--- Three engines only. Google AI Overview and Claude are absent, and Google AI Overview is the AI surface most Hong Kong consumers meet first.
--- The score is one-time. Trend tracking requires the US$50 per month HubSpot AEO product.
--- Brands with a thin footprint in English-language training data, common for Hong Kong SMEs and mid-market firms, may receive a low or uninformative score that reflects data scarcity rather than performance.
Neither tool replaces a full technical SEO audit, and neither can guarantee an AI assistant will cite you. Both are diagnostics, not outcomes.
Which tool should each type of buyer choose?
Run UD AEO Auditor first if you own the website and need a fix list: IT Directors, Heads of Digital and web teams. Run HubSpot AI Search Grader first if you own the brand narrative and need a perception score for a board paper: CMOs and brand leads. Hong Kong bilingual sites should start with UD. Teams already on Marketing Hub Professional should activate HubSpot AEO before buying anything else.
Verdict by buyer type
--- IT Director or Head of Digital Transformation with a site to fix: UD AEO Auditor. You get a ticket-ready list in 30 seconds, in Chinese if you prefer.
--- CMO or brand lead preparing a board paper: HubSpot AI Search Grader for the perception snapshot, then UD to explain the structural reasons behind it.
--- Hong Kong enterprise with bilingual or trilingual content: UD first. A structure scan works regardless of how thin your English training-data footprint is.
--- Existing HubSpot Marketing Hub Professional or Enterprise customer: Activate HubSpot AEO, which is already included, then run UD's free scan to fill the technical gap.
--- Team that needs weekly trend data at a fixed price: HubSpot AEO at US$50 per month is the published route. Re-run UD monthly for the structure side at no cost.
--- Team that needs someone to implement the fixes: UD, because the scan connects to a Hong Kong-based implementation team. HubSpot's product stops at recommendations.
Because both checks are free and take under two minutes combined, the honest recommendation for most enterprise readers is to run both today and compare what each reveals about the same brand.
What is the correct next step?
The right first move is to establish a baseline before any budget is committed. Run the structure scan on your primary domain, run the perception grade on your brand name, and put both scores in front of the people who own the website and the people who own the narrative. The gap between the two reports is usually where the AEO programme should start.
What matters afterwards is not the score but whether someone turns the findings into changes that AI engines can actually read. We understand AI. We understand you. With UD by your side, AI never feels cold.
Reviewed by the UD enterprise AI team. Facts verified against the UD AEO Auditor and HubSpot AI Search Grader landing pages on 24 September 2026. Prices are as published by each vendor and may change.
You have the comparison. The next step is your own baseline. Run the free 30-second scan on your domain, and if the findings need hands, we'll walk you through every step, from prioritising the fix list to implementation and monthly re-scans, with a Hong Kong team that has served enterprises since 1998.
