Company lists · Data refreshed September 2026

Top 12 Email testing software companies based in the United States

RevenueBase identified 28 email testing software companies headquartered in the United States as of September 2026 and tracks 549 professional contacts across them, including 63 with verified work emails. New York is the largest hub.

This list covers email testing 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 14, 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.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 14, 2026 86% judged on-target in blind review
28Companies
549Contacts tracked
63Verified emails
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The 12 largest email testing software companies based in the United States

Ranked by team size
Top 12 of 28 email testing software companies based in the United States, ranked by team size, largest first. Data refreshed Sep 14, 2026. RevenueBase Smart Search rates how each company's information relates to email testing software companies: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#CompanyRevenueBase Smart SearchHeadquartersEmployeesContacts
1Indirect evidenceCambridge, MA, United StatesHQ checked Sep 14, 202651-20070 contacts →

Indirect evidence

“At Litmus, we know the importance of continuous innovation.”

Source: RevenueBase Database · checked Sep 14, 2026
2Partial evidenceCentennial, CO, United StatesHQ checked Sep 14, 202611-5036 contacts →

Partial evidence

“Put your best email forward with Email on Acid!”

Source: RevenueBase Database · checked Sep 14, 2026
3Partial evidenceSan Francisco, CA, United StatesHQ checked Sep 14, 202611-5026 contacts →

Partial evidence

“Empower your team to create, innovate, and grow with the Dyspatch Email Builder.”

Source: RevenueBase Database · checked Sep 14, 2026
4Strong evidencePinedale, WY, United StatesHQ checked Sep 14, 202611-5025 contacts →

Strong evidence

“GlockApps Software is a privately held company that offers multiple email marketing solutions to help businesses reach the inbox and solve email deliverability issues.”

Source: RevenueBase Database · checked Sep 14, 2026
5Partial evidenceCharlotte, NC, United StatesHQ checked Sep 14, 202611-5023 contacts →

Partial evidence

“Inbox Monster helps email teams send epic messages to every inbox.”

Source: RevenueBase Database · checked Sep 14, 2026
6Partial evidenceLos Angeles, CA, United StatesHQ checked Sep 14, 202651-20019 contacts →

Partial evidence

“Modern email delivery for developer and product teams in growing digital companies.”

Source: RevenueBase Database · checked Sep 14, 2026
7Strong evidenceSchneider, IN, United StatesHQ checked Sep 14, 202611-5013 contacts →

Strong evidence

“Smarter, high-volume email delivery software for tech leaders & marketers.”

Source: RevenueBase Database · checked Sep 14, 2026
8Strong evidenceAustin, TX, United StatesHQ checked Sep 14, 20261,001-5,00011 contacts →

Strong evidence

Email marketing software for media, publishing, and brand engagement.”

Source: RevenueBase Database · checked Sep 14, 2026
9Partial evidenceCincinnati, OH, United StatesHQ checked Sep 14, 202611-504 contacts →

Partial evidence

“StoryPorts helps distributed teams create, review, test, and ship better email campaigns from start to finish.”

Source: RevenueBase Database · checked Sep 14, 2026
10Indirect evidenceFleetwood, PA, United StatesHQ checked Sep 14, 20261-103 contacts →

Indirect evidence

“Your Design.”

Source: RevenueBase Database · checked Sep 14, 2026
11Strong evidenceSchneider, IN, United StatesHQ checked Sep 14, 202611-501 contacts →

Strong evidence

“Discover why transactional senders and marketers alike trust their GreenArrow email software.”

Source: RevenueBase Database · checked Sep 14, 2026
12Partial evidenceSykesville, MD, United StatesHQ checked Sep 14, 20261-101 contacts →

Partial evidence

“Serious Email helps agencies and medium/large businesses create, manage and send HTML emails up to 80% faster than typical methods and services.”

Source: RevenueBase Database · checked Sep 14, 2026

Showing 12 of 28 email testing software companies based in the United States

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Email testing software companies based in the United States at a glance

As of Sep 14, 2026
11.5%Verified-email coverage
19.6Average contacts per company
11-50Median size (employees)
14.3%Largest-city concentration · New York
Sep 14, 2026Page data refreshed

Companies by employee count

1-10
8
11-50
15
51-200
2
201-500
1
501-1,000
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 28 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 email testing 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 “email testing 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 email testing 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 email testing 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, 63 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 14, 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 email testing 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 email testing software companies are there based in the United States?

RevenueBase identified 28 email testing 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?

Litmus, headquartered in Cambridge, tops this list with the largest team on record.

Which city has the most email testing software companies?

New York leads with 4 headquartered companies, followed by Los Angeles (2) and San Francisco (2).

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 63 verified decision-maker contacts tracked across these 28 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 14, 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.