Cal.com is cited in all 18 sampled answers and is the first-listed pick on the open-source scheduling query across every engine, leading share of voice at 40.1% just ahead of Calendly (35.8%). The one soft spot: on the category and head-to-head questions, the engines still lead with Calendly as the reference point.
Three real buyer queries, run across ChatGPT, Gemini and Perplexity in two trials each. Cal.com was cited in every single answer. The difference is how strongly each engine backs it, and whether Calendly gets treated as the brand to beat.
| Query | ChatGPT | Gemini | Perplexity |
|---|---|---|---|
| What is the best Calendly alternative in 2026? | Recommended | Recommended | Recommended |
| Cal.com vs Calendly, which should I use? | Split verdict | Split verdict | Named first |
| What's a good open-source scheduling tool for my team? | Top pick | Top pick | Top pick |
The pattern worth noticing: Cal.com is the outright first pick whenever the question is about open-source scheduling, but on “best Calendly alternative” and “Cal.com vs Calendly” the engines anchor on Calendly first and hand it the framing. Perplexity is the exception, ranking Cal.com first on the head-to-head, which is why it scores 87 to ChatGPT's 83 and Gemini's 80.
Share of voice across all 18 answers: how often each brand is named when buyers ask about scheduling tools. Cal.com edges out the market's default name.
Others: TidyCal (6.1%), Chili Piper (3.3%), SavvyCal (2.8%) and YouCanBookMe (0.9%). Cal.com leads on total mentions, but Calendly stays close because the engines keep it in frame as the point of comparison, even in answers that ultimately recommend Cal.com.
“Cal.com is widely considered the reigning champion of open-source meeting schedulers.”
Gemini in response to “What's a good open-source scheduling tool for my team?”
Re-anchor the current commercial positioning. Every engine still describes Cal.com through its pre-April-2026 open-source identity, and ChatGPT and Gemini point self-hosters to the cal.diy fork as the free way to run it. That framing is now out of date: per Cal.com's own April 2026 announcement (cal.com goes closed-source, and why), the commercial product went closed-source and the community edition became the separately branded cal.diy (now MIT). In effect, the engines are pointing scheduling buyers to the free fork on the strength of Cal.com's old story.
The highest-impact fix is to publish authoritative, structured pages that state the current positioning: a licensing and About page, a clear cal.com-vs-cal.diy explainer, and updated self-hosting docs. Give the engines fresh sources to cite and they stop defaulting buyers to the free self-hosted option. This is a useful lesson for any brand that ships a big repositioning: AI answers lag your latest messaging until new, well-structured pages give the models something current to quote.
This free mini samples 3 queries. The full audit is the complete, defensible picture: