Pricing
ShelfScore charges a flat rate per store. Sixthshop charges by credits, where each credit roughly equals one product action. The model difference matters most when your catalog grows. A 500-product store on Sixthshop's $29.99 Growth tier (200 credits) gets less than half a full audit per month. The same store on ShelfScore's $49 Starter tier gets unlimited audits, weekly re-audits, full history.
If your active catalog is under 30 products and you want occasional one-off rewrites, Sixthshop's entry tier is cheap. If your catalog is anywhere from 50 to 5000+ SKUs and you want to know the AI visibility state of your whole store on an ongoing basis, ShelfScore's structure costs less per audit by an order of magnitude.
For a deeper look at why this matters across the category, see Credit-metered vs flat-rate AI visibility tools.
Audit scope
ShelfScore audits three layers: bot access (robots.txt and AI crawler permissions for GPTBot, ClaudeBot, PerplexityBot, Google-Extended), JSON-LD schema across nine types cited against the schema.org spec, and product data completeness (GTINs, descriptions, images, alt text, returns, shipping). The premise is that AI search readiness is a three-layer problem and one weak layer breaks the chain.
Sixthshop's advertised audit focuses on the product page content layer: titles, descriptions, FAQs, JSON-LD generation, alt text. Their feature set does not list robots.txt analysis or AI crawler access auditing. If your store's robots.txt blocks GPTBot, no amount of perfect product-page schema will make your store visible to ChatGPT Shopping.
Schema authority
ShelfScore audits JSON-LD against the published schema.org vocabulary. Every check maps to a specific schema.org type and property, and the fix instructions cite the spec.
Sixthshop's listing references "UCP-Compliant JSON-LD @graph Schema" and a "0-100 UCP Readiness Score." UCP, Google's Universal Commerce Protocol announced at NRF 2026 in January, is a separate standard for agentic commerce checkout, fulfillment, discount, and catalog capabilities. Per Google Developers Blog, UCP uses JSON Schema (not JSON-LD), and the ucp.dev specification does not define a "UCP-compliant" standard for product JSON-LD markup.
This isn't a small technical quibble. AI search readiness depends on real standards. We audit against the schema.org spec because that's what AI engines actually parse.
Agency support
ShelfScore's Agency tier at $349 per month supports twenty-five client stores, a centralized agency dashboard, white-label PDF audit reports, and bulk audit scheduling. Sixthshop has no advertised agency tier.
If you manage multiple client stores, the agency-level features at $349 will pay for themselves on the first deliverable.