Sacra estimates that Cal hit $10M in annual recurring revenue (ARR) in July 2026, up 114% from $4.6M in 2024.

From launch in 2021 with no revenue, Cal crossed $1M ARR in 2023, reached $2.9M at the end of 2024, exited 2025 at $6.2M, and crossed the $10M threshold in mid-2026.

Enterprise contracts account for an estimated 60% of recurring revenue, while the Platform API's usage-based billing has grown toward roughly 25% of the mix. The remainder comes from self-serve team subscriptions.

Cal's largest publicly disclosed customer is Deel, the global HR and payroll platform, which uses Cal's scheduling infrastructure across its global operations and has reported saving over 6,000 hours per week. Other named enterprise customers include AngelList, Retell AI, and Pangea.app, a talent marketplace that attributed a 70% revenue boost to Cal's embedded scheduling solution.

At roughly 44 employees, Cal generates approximately $220,000 in revenue per employee, above Chili Piper's $168,000 per employee at a comparable stage, which points to the leverage of an engineering-heavy team with minimal sales overhead.

Cal's most recent disclosed valuation is $150M post-money, set at its Series A in April 2022. The round raised $25M and was led by Seven Seven Six, with participation from Obvious Ventures, OSS Capital, and strategic angels including the CEOs of Shopify and Vercel.

The Series A followed a $7.4M seed round closed in December 2021, led by OSS Capital, with angel investors including Naval Ravikant, YouTube co-founder Chad Hurley, Balaji Srinivasan, Confluent co-founder Neha Narkhede, MongoDB co-founder Eliot Horowitz, Vercel CEO Guillermo Rauch, and Supabase CEO Paul Copplestone.

PitchBook records an additional early-stage venture round completed in April 2025.

Cal has raised a confirmed $32.4M in primary equity across its seed and Series A, with the co-founders retaining approximately 75% of the company after those two rounds.

Cal is a scheduling platform for individuals, teams, and enterprises that creates shareable booking links and embeds scheduling into other products. A user connects Google Calendar or Outlook, sets availability, and gets a personal link, such as cal.com/jane, that anyone can use to pick an open time slot. Both parties then receive a calendar invite automatically, with a video link attached if needed.

The free individual tier includes unlimited event types, unlimited calendar connections, workflow automation for reminders and follow-ups, built-in payment collection via Stripe, and Cal Video, Cal's own video conferencing layer. A consultant could run a 15-minute discovery call, a 60-minute paid session, and a group workshop from a single Cal account, each with its own availability rules, buffer times, and booking limits.

For teams, Cal adds round-robin distribution, routing incoming bookings across available team members, collective events that find a slot when multiple people are free at the same time, and routing forms that qualify a booker through branching logic before assigning them to the right person. Larger organizations get attribute-based routing, where bookings are assigned dynamically based on variables such as region, deal size, or language, putting Cal in direct competition with dedicated sales routing tools.

The clearest product distinction is the Platform API, which Cal describes as its "Stripe for Time" play. Instead of buying a seat for every tutor, clinician, or service provider on a platform, a marketplace integrates Cal's API and React components, called Cal Atoms, into its own interface. The end user never sees Cal branding and instead books inside the marketplace. Pricing scales by booking volume rather than headcount, which fits two-sided platforms that might have thousands of providers but only a few hundred bookings per month.

Cal also offers Cal.ai, an AI voice agent that makes and receives phone calls to schedule, confirm, and follow up on appointments. A user sets a trigger, writes a prompt defining the agent's behavior, and assigns a phone number. The agent conducts natural-language phone conversations, logs transcripts, and syncs outcomes back into the Cal dashboard. Separately, Cal has published an MCP server that lets AI coding assistants and autonomous agents interact with Cal's scheduling infrastructure programmatically, checking availability, creating bookings, and modifying events through conversational interfaces.

Cal sells through two pricing surfaces. The first is a per-seat SaaS subscription for teams and organizations, starting at $12 per user per month on annual billing and rising to $28 per user per month for the Organizations tier with SSO, SCIM, and compliance certifications. Enterprise contracts are custom-quoted and include dedicated infrastructure, SLA-backed support, and HRIS integrations.

The second is the Platform API, priced by booking volume rather than seats. A marketplace pays $299 per month for up to 500 bookings, $2,499 per month for up to 5,000, and negotiated rates above that. This differs structurally from Calendly's seat-based model: a telehealth platform with 800 clinicians would pay Calendly up to $12,800 per month in seat fees, while Cal's Platform API might cost less depending on actual booking volume. Cal.ai voice agent usage adds a consumption layer on top, billed at $0.29 per minute.

Go-to-market has historically been product-led, with Cal's open-source repository accumulating over 47,000 GitHub stars and nearly 1,000 contributors. Developers discovered Cal on GitHub, self-hosted it, and a subset converted to paid SaaS or enterprise licenses. In April 2025, Cal moved its main codebase to a private repository and created cal.diy as a community fork, a transition that mirrors the license changes made by HashiCorp, Elastic, and Redis as those companies pushed upmarket and sought to protect enterprise revenue from self-hosted free-riders.

With roughly 90% of the team being engineers and co-founder salaries historically set at $70,000 per year, Cal's cost structure appears lean relative to revenue. The company was approaching its first profitable month as early as mid-2023, suggesting the business ran close to breakeven even as it scaled.

The scheduling market has split into three layers: horizontal PLG tools, bundled suite products, and infrastructure-first developer tools. Cal competes across all three, with its clearest product differentiation in infrastructure.

Calendly is the largest standalone scheduling tool, with Sacra estimating it hit $349M ARR at the end of 2024, up 40% year over year, against a $3B valuation from its 2021 Series B. Calendly built distribution through a viral loop in which each shared booking link exposes recipients to the Calendly brand and drives organic signups. It claims users inside 86% of Fortune 500 companies and roughly 53% U.S. market share in scheduling.

Cal's critique of Calendly is structural: the majority of its roughly 500-person team is in go-to-market roles, and Cal argues that has slowed investment in developer-facing infrastructure. Cal's free tier is more generous than Calendly's, which limits users to a single event type, and Cal's Platform API has no Calendly equivalent at comparable pricing.

Calendly has since added an AI assistant, a meeting notetaker, a scheduling API, and an MCP server, moving beyond booking links toward scheduling infrastructure. The competitive question is which platform becomes the default scheduling layer for AI agents and embedded enterprise workflows.

Chili Piper sits at $43M ARR in 2025, up 23% year over year, valued at $625M. Its core product routes inbound form submissions directly to a sales rep's calendar, doubling conversion rates for B2B revenue teams. Chili Piper's average contract value is over $10,000, and its net revenue retention runs above 140%, indicating deep integration in enterprise sales stacks.

Cal competes here through attribute-based routing and routing forms on the Organizations tier, but at a lower price point and without Chili Piper's dedicated demand conversion platform. Default, a newer lead routing platform, takes a similar approach, bundling scheduling as one module inside a broader inbound automation stack, and is explicitly agnostic about whether customers use Calendly or Cal as the underlying scheduler.

Google Calendar now includes a native appointment scheduler, Microsoft Bookings ships bundled with Office 365, and HubSpot includes a Calendly-equivalent scheduling tool free with its CRM. These bundled products commoditize the basic booking link for buyers already inside those ecosystems.

Cal's counter-position is that the platform incumbents do not offer self-hosting, white-label embedding, HIPAA and SOC 2 compliance, or a volume-based API pricing model. For a telehealth company, a talent marketplace, or an AI voice platform, those bundled scheduling tools are not viable substitutes. Doodle, once a credible group scheduling alternative, effectively exited the market, valued at just $2.3M in a 2025 acquisition offer, which shows how quickly undifferentiated scheduling tools can get squeezed between PLG leaders and suite bundles.

Cal's core scheduling apps market is estimated at $674M in 2025, growing toward $2.2B by 2034. The broader expansion case is that scheduling, when sold as infrastructure rather than a standalone app, can sit inside markets much larger than the scheduling category itself.

Two-sided marketplaces that connect service providers with customers have a scheduling constraint. Tutoring platforms, legal services, healthcare networks, talent marketplaces, and home services apps need to match a customer with an available provider and confirm a time without requiring every provider to buy a separate scheduling subscription.

Cal's Platform API, priced by booking volume rather than seats, targets this use case. Pangea.app's 70% revenue boost after integrating Cal's scheduling infrastructure points to the conversion impact when scheduling is built into the marketplace flow. The addressable market here extends beyond the $674M scheduling apps market to marketplace and vertical SaaS companies that need a scheduling layer.

As AI agents take on more coordination work, scheduling meetings, confirming appointments, and following up on no-shows, the scheduling layer shifts from a human-facing booking page to a machine-callable API. Cal's MCP server and Platform API make it a scheduling layer that AI agents can call directly, rather than only a product that end users interact with.

Retell AI, which processes 10 million calls per month, uses Cal's preset tools so its AI receptionists can check availability and book appointments during live phone calls. Cal.ai extends this in the other direction, letting Cal act as the calling agent. The calendar app market, broadly defined, is estimated at $5.7B in 2024, and if scheduling becomes a primitive that AI agents consume at scale, the relevant TAM extends beyond what a human-facing booking tool can address.

Healthcare, legal, and financial services are large scheduling markets where compliance requirements, HIPAA, SOC 2, ISO 27001, disqualify many consumer-grade scheduling tools. Cal's enterprise compliance certifications, combined with its self-hosting option and white-label embedding, make it one of the few scheduling platforms able to serve these verticals at the infrastructure layer.

Shimmer, an ADHD coaching telehealth platform, and Kiaora, a women's health provider, both use Cal for patient scheduling because of its HIPAA compliance and multi-provider support. As telehealth and digital health platforms scale, demand for a scheduling infrastructure layer that can handle clinical workflows, provider credentialing, and patient data privacy increases with them.

Commoditization from above: Google, Microsoft, and HubSpot are bundling native scheduling into their existing productivity and CRM suites at no additional cost, which erodes the addressable market for standalone scheduling tools among buyers already inside those ecosystems, and Cal's open-source heritage and developer positioning do not insulate it from buyers who use what comes with their existing software stack.

Closed-source backlash: Cal's April 2025 move from open-source to a private codebase, mirroring similar transitions at HashiCorp, Elastic, and Redis, risks alienating the developer community that drove its initial 47,000 GitHub stars and organic enterprise pipeline, particularly if the cal.diy community fork matures into a credible self-hosted alternative that undercuts Cal's ability to convert developers into paying enterprise customers.

Calendly's infrastructure pivot: Calendly's addition of a scheduling API, MCP server, and AI assistant means the incumbent now competes directly on the developer and agentic scheduling surface that Cal has treated as its primary differentiation, and Calendly's 36x revenue advantage and established enterprise relationships give it distribution leverage in any head-to-head infrastructure comparison.