Company lists · Data refreshed September 2026
Top 25 Online availability calendar software companies based in the United States
RevenueBase identified 108 online availability calendar software companies headquartered in the United States as of September 2026 and tracks 559 professional contacts across them, including 168 with verified work emails. San Francisco is the largest hub.
This list covers online availability calendar software companies headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 29, 2026.
Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.
The 25 largest online availability calendar software companies based in the United States
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 57 contacts → | ||||
Partial evidence “SUMO is a customer engagement platform that includes online Appointment, Event, and Field Sales scheduling, built fully native on Salesforce.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 2 | 46 contacts → | ||||
Indirect evidence “Cal.com is a modern, fully customizable scheduling platform built for teams that care about both power and design.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 3 | 37 contacts → | ||||
Partial evidence “Clockwise is an AI-powered calendar assistant that builds smarter schedules for everyone by coordinating the way individuals, teams, and companies prefer to work.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 4 | 31 contacts → | ||||
Indirect evidence “Picktime is one of the world's leading scheduling platforms providing a quick, intuitive tool that enables professionals to book meetings with clients.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 5 | 22 contacts → | ||||
Partial evidence “Setmore offers a free online scheduling platform that empowers you to balance your scheduling, connect with customers, and grow your brand.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 6 | 19 contacts → | ||||
Partial evidence “Vimcal is the world's fastest calendar, beautifully designed for people who have too many meetings.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 7 | 18 contacts → | ||||
Strong evidence “AddEvent is a cutting-edge software company providing best-in-class calendar marketing and event management solutions to thousands of companies worldwide.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 8 | 13 contacts → | ||||
Indirect evidence “Are you and your staff constantly battling to answer the reservations phone and serve your customers at your place?” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 9 | 13 contacts → | ||||
Partial evidence “The trusted partner in comprehensive B2B appointment, event, and association management software, building enduring partnerships with our clients to empower them to create…” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 10 | 11 contacts → | ||||
Partial evidence “TimeTap Online Scheduling is a simple & effective tool for the multifaceted and over-stressed life of service providers & appointment based businesses.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 11 | 11 contacts → | ||||
Indirect evidence “At Book Like A Boss, we're redefining how businesses engage with their clients, streamline operations, and maximize revenue.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 12 | 11 contacts → | ||||
Partial evidence “We are Calendar, trying to make the world a much more productive place.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 13 | 11 contacts → | ||||
Partial evidence “Flexible scheduling software designed to help you grow, because booking time should never get in the way of success.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 14 | 9 contacts → | ||||
Partial evidence “Every scheduling tool books by availability, whoever grabs the open slot wins.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 15 | 6 contacts → | ||||
Strong evidence “StormSource Software, which does business as AppointmentPlus, is a worldwide leader in online scheduling solutions for growing businesses, enterprises, higher education…” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 16 | 6 contacts → | ||||
Indirect evidence “An cloud-based scheduling platform for growth focused leader looking to speed up their sales and fullfillment processes.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 17 | 5 contacts → | ||||
Indirect evidence “At Undock, we're excited to give you the power to focus on what matters most-important meetings, impactful work, and meaningful relationships.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 18 | 5 contacts → | ||||
Indirect evidence “Tired of going back and forth with your leads or clients just to book a call?” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 19 | 5 contacts → | ||||
Partial evidence “Koalendar is an intuitive software for scheduling appointments, meetings, and events.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 20 | 5 contacts → | ||||
Partial evidence “Full Slate offers comprehensive software-as-a-service (SaaS) scheduling.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 21 | 5 contacts → | ||||
Partial evidence “Casino Schedule Ease is a software company that focuses on scheduling and time & attendance solutions for the casino industry.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 22 | 5 contacts → | ||||
Partial evidence “FUNTARO is an Event planning software that allows users to schedule events like corporate happy hours, family and friends get-togethers, Game nights at sports bars, picnics…” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 23 | 4 contacts → | ||||
Indirect evidence “Are you a small business owner bogged down by scheduling woes?” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 24 | 4 contacts → | ||||
Indirect evidence “Connecting Business and Clients in Real-Time Qbitt is the platform that let's you book appointments on your time.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
| 25 | 4 contacts → | ||||
Indirect evidence “About 8 years ago Bookafy was started as a side project to help our own team schedule our appointments.” Source: RevenueBase Database · checked Sep 29, 2026Thanks. The Data Team will review it. | |||||
RevenueBase Smart Search
RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: online availability calendar software companies. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.
- Strong evidence
- The company's own public description of its business names online availability calendar software companies.
- Partial evidence
- Its own public description names part of online availability calendar software companies, so it works in or next to the category without describing itself that way.
- Indirect evidence
- The description shown does not name online availability calendar software companies. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.
RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.
Showing 25 of 108 online availability calendar software companies based in the United States
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Online availability calendar software companies based in the United States at a glance
As of Sep 29, 2026Companies by employee count
Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 108 companies.
How this list was built
Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among online availability calendar software companies, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.
- Source
- The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
- What qualifies
- Companies headquartered in the United States whose own description of what they do matches “online availability calendar software companies”. Matching reads each company's description, not its industry code or its name.
- RevenueBase Smart Search
- RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names online availability calendar software companies), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
- What we exclude
- Companies whose own description does not clearly place them among online availability calendar software companies, and records with no verified work email. Companies headquartered outside United States are excluded even when they keep an office there.
- Match quality
- In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
- Ranking
- Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
- Verification
- Every listed company carries at least one verified work email, 168 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
- Refresh
- This page's figures were pulled from the company graph on September 29, 2026. Lists refresh periodically as the graph is re-checked.
- Corrections
- Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.
Frequently asked
What is RevenueBase Smart Search?
RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names online availability calendar software companies, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.
How many online availability calendar software companies are there based in the United States?
RevenueBase identified 108 online availability calendar software companies headquartered in the United States as of September 2026, matched on each company's own description of what it does rather than its industry code.
What is the largest company on this list?
Sumo Scheduler, headquartered in Atlanta, tops this list with the largest team on record.
Which city has the most online availability calendar software companies?
San Francisco leads with 14 headquartered companies, followed by New York (10) and Austin (6).
How do I get contact information for these companies?
A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 168 verified decision-maker contacts tracked across these 108 companies.
How current is this list?
The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 29, 2026.
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About this data
RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.
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