Sill vs xFunnel (now HubSpot) 2026
Head-to-head comparison of two AI visibility platforms. xFunnel (now HubSpot) (AI search analytics platform (acquired by HubSpot, Oct 2025)) versus Sill (AI visibility simulator with counterfactual analysis and daily SOV tracking across 6 platforms). Here is what each platform does, where each is stronger, and which one fits your team.
Company overview
| Sill | xFunnel (now HubSpot) | |
|---|---|---|
| Focus | Standalone AI visibility simulator with counterfactual analysis, daily SOV tracking across 6 platforms, GEO recommendations, and experimentation layer in development | AI search analytics platform known for its 5M AI answers research dataset and xFlow visualization. Acquired by HubSpot October 2025; no longer available as a standalone product. Being integrated into HubSpot Marketing Hub. |
| Founded | 2024 | 2024 (acquired after ~10 months) |
| HQ | United States | Israel (now part of HubSpot) |
| Funding | Bootstrapped | Undisclosed (acquired by HubSpot for undisclosed amount, Oct 31, 2025) |
| Customers | 139+ brands across 86 industries | Pre-acquisition: enterprise B2B marketing teams. Post-acquisition: HubSpot Marketing Hub customers only |
At a glance
| Sill | xFunnel (now HubSpot) | |
|---|---|---|
| Availability | Standalone product, self-serve signup | No longer standalone; HubSpot Marketing Hub only |
| Starting price | $0/mo (free tier) | HubSpot Marketing Hub required (starts at $890/mo for Professional) |
| AI platforms tracked | 6 in all plans | 5 pre-acquisition (ChatGPT, Perplexity, Gemini, Claude, AI Overviews) |
| Free tier | Yes (5 prompts, 6 platforms) | No (HubSpot subscription required) |
| Vendor lock-in | None (monthly billing, cancel anytime) | Full HubSpot ecosystem lock-in |
| GEO recommendations | Yes (748 across 62 brands, 87% on-site fixes) | Content optimization recommendations (pre-acquisition) |
| Experimentation / simulation | Counterfactual simulation in development | Research module (5M AI answers dataset), but no simulation |
| xFlow visualization | No | Yes (visual map of prompt-to-citation paths) — status post-acquisition unclear |
| GA4 integration | No | Yes (bot detection + AI traffic attribution) |
| Data continuity | Your data, your account | Migrating to HubSpot; unclear data continuity for existing users |
Feature comparison
| Feature | Sill | xFunnel (now HubSpot) |
|---|---|---|
| SOV tracking | Daily across 6 platforms | Pre-acquisition: 5 platforms. Post-acquisition: being integrated into HubSpot |
| GEO recommendations | Actionable on-site fixes (87% on-site) | Content optimization (pre-acquisition capability) |
| Counterfactual simulation | In development (quasi-experimental design) | No |
| Experimentation framework | Planned: within-brand controls, Bayesian estimation, placebo calibration | No formal experimentation framework |
| Research dataset | 139 brands, 86 industries, 7,442 AI responses | 1,500 companies, 5M AI answers, 25M citations (landmark study) |
| xFlow visualization | No | Yes (prompt-to-citation path mapping) |
| Bot detection | No | Yes (identifies AI crawlers in GA4) |
| Platform divergence analysis | Yes (55% brands differ 10+ points, 91.6% single-platform citations) | Not a named feature |
| Citation source tracking | Yes | Yes |
| Standalone access | Yes | No (HubSpot only since Oct 2025) |
| API | Roadmap | Was available pre-acquisition; HubSpot API integration in progress |
| CRM integration | No | Native HubSpot CRM integration |
Pricing comparison
| Tier | Sill | xFunnel (now HubSpot) |
|---|---|---|
| Free tier | $0/mo, 5 prompts, 6 platforms | Not available |
| Entry | Basic: $90/mo, 120 prompts, 6 platforms | xFunnel pre-acquisition: started at $45/mo. Now: HubSpot Marketing Hub Professional ($890/mo) |
| Mid | Pro: $225/mo, 360 prompts, 6 platforms | HubSpot Marketing Hub Enterprise ($3,600/mo) |
| Contract | Monthly billing, cancel anytime | HubSpot annual contracts typical |
| Switching cost | Low (self-serve, no lock-in) | High (full HubSpot ecosystem migration) |
| Data portability | CSV export, your data | Subject to HubSpot data policies |
Which platform fits your team
Choose Sill if you:
- +Were using xFunnel as a standalone product and need a replacement after the HubSpot acquisition
- +Do not want to commit to the full HubSpot ecosystem ($890+/mo) just for AI visibility monitoring
- +Want experimentation and counterfactual simulation capabilities (the analytical depth xFunnel was known for)
- +Need a standalone AI visibility tool without CRM lock-in
- +Want to start free and scale incrementally rather than committing to enterprise HubSpot pricing
- +Need daily SOV tracking across 6 AI platforms with GEO recommendations
- +Value data portability and low switching costs
Choose xFunnel (now HubSpot) if you:
- +Already use HubSpot Marketing Hub and want AI visibility integrated into your existing workflow
- +Need native CRM integration between AI visibility data and your sales pipeline
- +Want the xFlow visualization for prompt-to-citation path mapping (if it survives the integration)
- +Need GA4 bot detection to identify AI crawlers hitting your site
- +Are committed to the HubSpot ecosystem long-term and the incremental cost is acceptable
- +Value the 5M AI answers research dataset for historical benchmarking
Verdict
xFunnel built one of the most analytically rigorous AI visibility platforms in the market, anchored by a landmark study of 1,500 companies and 5 million AI-generated answers. Its acquisition by HubSpot in October 2025 validated the category but eliminated it as a standalone option. Former xFunnel users now face a choice: commit to HubSpot Marketing Hub (starting at $890/mo) to retain access, or find a standalone alternative. Sill is the closest match to what made xFunnel valuable. Both platforms prioritize analytical depth over simple dashboards. xFunnel’s research module demonstrated the kind of rigorous, data-driven approach to AI visibility that most monitoring tools lack; Sill’s counterfactual simulation and experimentation framework (in development) are building toward the same goal: separating real content impact from platform noise. For teams that valued xFunnel’s analytical rigor but do not want HubSpot ecosystem lock-in, Sill offers the most direct path forward: standalone access, a free tier, daily SOV tracking across 6 platforms, GEO recommendations, and an experimentation layer designed to answer the attribution question that xFunnel’s research first quantified.
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