Company lists · Data refreshed October 2026

Top 18 E-mailing and calendaring software as a service companies based in the United States

RevenueBase identified 66 company matches for e-mailing and calendaring software as a service companies associated with the United States as of October 2026 and tracks 432 professional contacts across them, including 111 with verified work emails. San Francisco is the largest hub.

This list covers company matches for e-mailing and calendaring software as a service companies associated with the United States, found by RevenueBase SmartSearch using the meaning of business descriptions in its company graph at Exact. Ranked by professionals tracked, largest first. Rows show recorded descriptions where available, Exact search membership and the snapshot date. Data refreshed October 19, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, 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.

How to read this list RevenueBase SmartSearch · Exact Recorded Oct 19, 2026 How this list was built
66Companies
432Contacts tracked
111Verified emails
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The 18 largest e-mailing and calendaring software as a service companies based in the United States

Ranked by team size
Top 18 of 66 company matches for e-mailing and calendaring software as a service companies based in the United States, ordered by professional contacts tracked in RevenueBase, largest first. Recorded Oct 19, 2026. The RevenueBase SmartSearch column shows Exact match membership in this saved search. Click a contact count to view that company's people. Totals use company locations recorded by RevenueBase; the displayed preview is a smaller selection.
#CompanyRevenueBase SmartSearchHeadquartersEmployeesContacts
1Exact matchSan Francisco, CA, United StatesHQ recorded Oct 19, 2026201-50097 contacts →

Exact match

“Hundreds of thousands of developers around the world use Nylas to increase velocity and seamlessly build customizable email and scheduling capabilities through state-of-the-art…”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
2Exact matchRochester, NY, United StatesHQ recorded Oct 19, 202611-5053 contacts →

Exact match

“Business Email Accounts, Calendaring, Contacts and Collaboration Services for Your Business from BlueTie.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
3Exact matchSan Francisco, United StatesHQ recorded Oct 19, 202611-5024 contacts →

Exact match

“Email was never meant to be this busy.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
4Exact matchSan Francisco, CA, United StatesHQ recorded Oct 19, 202611-5018 contacts →

Exact match

“AddEvent is a cutting-edge software company providing best-in-class calendar marketing and event management solutions to thousands of companies worldwide.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
5Exact matchMountain View, CA, United StatesHQ recorded Oct 19, 202611-5016 contacts →

Exact match

“Boomerang is the leader in thoughtful email productivity software that empowers people to focus on what matters on the world’s top email platforms.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
6Exact matchSan Diego, CA, United StatesHQ recorded Oct 19, 202611-5014 contacts →

Exact match

“Reliable and Secure email hosting services for SMB and Enterprise.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
7Exact matchLos Angeles, CA, United StatesHQ recorded Oct 19, 202651-20012 contacts →

Exact match

“Mail2World designs, delivers and supports a technology-leading and award-winning suite of carrier-class, Web-based email messaging and collaboration services.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
8Exact matchSpokane, WA, United StatesHQ recorded Oct 19, 202611-5011 contacts →

Exact match

“We are Calendar, trying to make the world a much more productive place.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
9Exact matchArdsley On Hudson, NY, United StatesHQ recorded Oct 19, 20261-1010 contacts →

Exact match

“Match My Email allows you to sync your emails and calendars automatically with Salesforce.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
10Exact matchMiami, FL, United StatesHQ recorded Oct 19, 20261-108 contacts →

Exact match

“Down-to earth Cloud services.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
11Exact matchSan Francisco, CA, United StatesHQ recorded Oct 19, 202611-508 contacts →

Exact match

“Do you want to make the most of your time?⌛ We made you over 60 free productivity tools for Gmail.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
12Exact matchCoral Gables, FL, United StatesHQ recorded Oct 19, 20261-105 contacts →

Exact match

“Cloud Services from B2B Cloud Solutions give you the power to collaborate using the Internet and intranet in your office to make doing business more efficient.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
13Exact matchSan Francisco, CA, United StatesHQ recorded Oct 19, 202611-505 contacts →

Exact match

“Full Slate offers comprehensive software-as-a-service (SaaS) scheduling.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
14Exact matchBrooklyn, United StatesHQ recorded Oct 19, 20261-104 contacts →

Exact match

“At Undock, we're excited to give you the power to focus on what matters most-important meetings, impactful work, and meaningful relationships.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
15Exact matchMiami, FL, United StatesHQ recorded Oct 19, 20261-103 contacts →

Exact match

“CalendarBridge helps professionals, teams, and organizations manage their multiple calendars seamlessly and with confidence.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
16Exact matchSouthfield, MI, United StatesHQ recorded Oct 19, 202611-502 contacts →

Exact match

Recorded description not available.

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
17Exact matchIrvine, CA, United StatesHQ recorded Oct 19, 20261-101 contacts →

Exact match

“For as little as $10/mn pp, you and your staff can share email, appointment calendars, contacts.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase
18Exact matchBelton, TX, United StatesHQ recorded Oct 19, 20261-101 contacts →

Exact match

“We provide online collaboration tools for Agents.”

Recorded in the RevenueBase company graph · Oct 19, 2026 · View company records in RevenueBase

Showing 18 of 66 e-mailing and calendaring software as a service companies based in the United States

See the full list, filter by size, metro and specialty, and access 111 tracked professional contacts with verified work emails. Direct dials are available where recorded.

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E-mailing and calendaring software as a service companies based in the United States at a glance

As of Oct 19, 2026
25.7%Verified-email coverage
6.5Average contacts per company
1-10Median size (employees)
9.1%Largest-city concentration · San Francisco
Oct 19, 2026Page data refreshed

Companies by employee count

1-10
43
11-50
19
51-200
2
201-500
1
1,001-5,000
1

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 66 companies.

How this list was built

The recorded descriptions help you assess these company matches. Check a company’s website for its current services and locations.

Source
The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase SmartSearch, the natural-language company search available to every RevenueBase user.
What qualifies
Company records associated with the United States whose business descriptions match “e-mailing and calendaring software as a service companies” by meaning at the Exact setting. Descriptions are compiled in the RevenueBase company graph from public websites, profiles and company information where available; they are not guaranteed quotations from the company's website.
RevenueBase SmartSearch
Describe a niche company in your own words to find businesses by meaning. Exact, Similar, Related and Broad control the breadth of RevenueBase SmartSearch. This saved list uses Exact. Each row's Exact match badge shows inclusion in that search, not an individual score or a service-quality judgment.
Public preview
The public preview omits records without a verified work email. Where headquarters information is recorded, preview rows are also filtered to this page’s location. Dataset totals and geographic summaries describe the full matched records before these preview filters.
Match quality
RevenueBase's August 25, 2026 study assessed 4,198 description/company pairs across matching settings. The publisher reports 86% good or better at Exact. This evaluates the method across queries; it does not audit this individual list. Recorded company descriptions, where available, help you judge each match yourself. Read the full methodology: how the lists are built and what the study measures.
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 displayed company carries at least one verified work email. RevenueBase tracks 111 professional contacts with verified work emails across the full matched dataset. 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 October 19, 2026. Lists refresh periodically as the graph is re-checked.
Record context
Company records and descriptions can change. Check the company's website for its current services and locations.

Frequently asked

What is RevenueBase SmartSearch?

RevenueBase SmartSearch finds niche companies by the meaning of their business descriptions in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit your description. This list uses Exact for “e-mailing and calendaring software as a service companies”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many e-mailing and calendaring software as a service companies are there based in the United States?

RevenueBase identified 66 company matches for e-mailing and calendaring software as a service companies associated with the United States as of October 2026, using the meaning of business descriptions at Exact. This is the recorded matched set in the RevenueBase company graph.

What is the largest company on this list?

NYLAS tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.

Which city has the most e-mailing and calendaring software as a service companies?

San Francisco leads with 6 company records, followed by Miami (4) and Austin (3).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work limited free results with 500 credits to start. Upgrading provides access to the 111 professional contacts with verified work emails tracked across these 66 companies; direct dials are available where recorded.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on October 19, 2026.

Ready to reach these companies? Verified emails and direct dials for all 66 e-mailing and calendaring software as a service companies based in the United States. Start with a free account, no credit card.

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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 SmartSearch, 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.