Exhibit 99.1

Endurance International Group Reports 2017 Third Quarter Results

BURLINGTON, MA (October 31, 2017) — Endurance International Group Holdings, Inc. (NASDAQ: EIGI), a leading provider of cloud-based platform solutions designed to help small and medium-sized businesses succeed online, today reported financial results for its third quarter ended September 30, 2017.

“I am pleased to report third quarter results that reflect solid performance in both web presence and email marketing,” commented Jeffrey H. Fox, president and chief executive officer of Endurance International Group. “Our 2017 plan to deliver profitable growth while focusing on higher lifetime revenue customers has been demonstrated in our year to date performance. Our priorities for the rest of the year are to continue to simplify our operations and to invest in initiatives that we believe will drive future growth and long-term value for our customers.”

Third Quarter 2017 Financial Highlights

Third Quarter Operating Highlights

Fiscal 2017 Guidance

The company is increasing its adjusted EBITDA expectations for the year by approximately $8 million from the midpoint of prior guidance. As of the date of this release, October 31, 2017, for the full year ending December 31, 2017, the company now expects:

Adjusted EBITDA and free cash flow are non-GAAP financial measures. A reconciliation of these non-GAAP financial measures to their most comparable measure calculated in accordance with GAAP is provided in the financial statement tables included at the end of this press release.

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Conference Call and Webcast Information

Endurance International Group’s third quarter 2017 financial results teleconference and webcast is scheduled to begin at 8:00 a.m. EDT on Tuesday, October 31, 2017. To participate on the live call, analysts and investors should dial (888) 734-0328 at least ten minutes prior to the call. Endurance International Group will also offer a live and archived webcast of the conference call, accessible from the Investor Relations section of the company’s website at http://ir.endurance.com.

Non-GAAP Financial Measures

In addition to our financial information presented in accordance with GAAP, we use adjusted EBITDA and free cash flow, which are non-GAAP financial measures, to evaluate the operating and financial performance of our business, identify trends affecting our business, develop projections and make strategic business decisions. A non-GAAP financial measure is a numerical measure of a company’s operating performance, financial position or cash flow that excludes amounts that are included in the most directly comparable measure calculated and presented in accordance with GAAP or includes amounts that are excluded from the most directly comparable measure calculated and presented in accordance with GAAP.

Our non-GAAP financial measures may not provide information that is directly comparable to that provided by other companies in our industry, as other companies in our industry may calculate non-GAAP financial results differently. In addition, there are limitations in using non-GAAP financial measures because they are not prepared in accordance with GAAP and exclude expenses that may have a material impact on our reported financial results. For example, adjusted EBITDA excludes interest expense, which has been and will continue to be for the foreseeable future a significant recurring expense in our business. The presentation of non-GAAP financial information is not meant to be considered in isolation from, or as a substitute for, the most directly comparable financial measures prepared in accordance with GAAP. We urge you to review the additional information about adjusted EBITDA and free cash flow shown below, including the reconciliations of these non-GAAP financial measures to their comparable GAAP financial measures, and not to rely on any single financial measure to evaluate our business.

Adjusted EBITDA is a non-GAAP financial measure that we calculate as net (loss) income, excluding the impact of interest expense (net), income tax expense (benefit), depreciation, amortization of other intangible assets, stock-based compensation, restructuring expenses, transaction expenses and charges, SEC investigations reserve, (gain) loss of unconsolidated entities, and impairment of other long-lived assets. We view adjusted EBITDA as a performance measure and believe it helps investors evaluate and compare our core operating performance from period to period.

Free Cash Flow, or FCF, is a non-GAAP financial measure that we calculate as cash flow from operations less capital expenditures and capital lease obligations. We believe that FCF provides investors with an indicator of our ability to generate positive cash flows after meeting our obligations with regard to capital expenditures (including capital lease obligations).

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Key Operating Metrics

Total Subscribers - We define total subscribers as the approximate number of subscribers that, as of the end of a period, are identified as subscribing directly to our products on a paid basis, excluding accounts that access our solutions via resellers or that purchase only domain names from us. Subscribers of more than one brand, and subscribers with more than one distinct billing relationship or subscription with us, are counted as separate subscribers. Total subscribers for a period reflects adjustments to add or subtract subscribers as we integrate acquisitions and/or are otherwise able to identify subscribers that meet, or do not meet, this definition of total subscribers. There were no adjustments for the third quarter of 2017.

Average Revenue Per Subscriber (ARPS) - We calculate ARPS as the amount of revenue we recognize in a period, including marketing development funds and other revenue not received from subscribers, divided by the average of the number of total subscribers at the beginning of the period and at the end of the period, which we refer to as average subscribers for the period, divided by the number of months in the period. See definition of “Total Subscribers” above. We believe ARPS is an indicator of our ability to optimize our mix of products and services and pricing and sell products and services to new and existing subscribers. ARPS does not represent an exact measure of the average amount a subscriber spends with us each month, since our calculation of ARPS is impacted by revenues generated by non-subscribers.

Forward-Looking Statements

This press release includes certain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, including statements concerning our updated financial guidance for fiscal year 2017, our expectations regarding our planned investment initiatives, and our expected financial and operational performance in general. These forward-looking statements include, but are not limited to, plans, objectives, expectations and intentions and other statements contained in this press release that are not historical facts, and statements identified by words such as “expects,” “believes,” “estimates,” “may,” “continue,” “positions,” “confident,” and variations of such words or words of similar meaning and the use of future dates. These forward-looking statements reflect our current views about our plans, intentions, expectations, strategies and prospects, which are based on the information currently available to us and on assumptions we have made. Although we believe that our plans, intentions, expectations, strategies and prospects as reflected in or suggested by those forward-looking statements are reasonable, we can give no assurance that these plans, intentions, expectations or strategies will be attained or achieved. Furthermore, actual results may differ materially from those described in the forward-looking statements and will be affected by a variety of risks and factors that are beyond our control including, without limitation: the possibility that our updated financial guidance may differ from expectations; that our planned initiatives will not result in a positive return on investment; that we will be unable to successfully enhance the customer product and service experience and improve customer satisfaction and retention through operational and

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infrastructure improvements; that we will encounter difficulties or delays in our efforts to build brand awareness of our key brands; that we will be unable to drive revenue growth by increasing ARPS through cross-selling and other product-related initiatives; that we will continue to experience decreases in our subscriber base; an adverse impact on our business from litigation or regulatory proceedings; an adverse impact on our business from our substantial indebtedness and the cost of servicing our debt; the rate of growth of the Small and Medium Business (“SMB”) market for our solutions; our inability to increase sales to our existing subscribers, or retain our existing subscribers; system or Internet failures; our inability to maintain or improve our competitive position or market share; and other risks set forth under the caption “Risk Factors” in our Quarterly Report on Form 10-Q for the period ended June 30, 2017 filed with the SEC on August 4, 2017 and other reports we file with the SEC.

We assume no obligation to update any forward-looking statements contained in this document as a result of new information, future events or otherwise.

About Endurance International Group

Endurance International Group Holdings, Inc. (NASDAQ: EIGI) (em)Powers millions of small businesses worldwide with products and technology to vitalize their online web presence, email marketing, mobile business solutions, and more. The Endurance family of brands includes: Constant Contact, Bluehost, HostGator, iPage, Domain.com, BigRock, SiteBuilder and SinglePlatform, among others. Headquartered in Burlington, Massachusetts, Endurance employs over 3,600 people across the United States, Brazil, India and the Netherlands. For more information, visit: www.endurance.com.

Endurance International Group and the compass logo are trademarks of The Endurance International Group, Inc. Constant Contact, the Constant Contact logo and other brand names of Endurance International Group are trademarks of The Endurance International Group, Inc. or its subsidiaries.

Investor Contact:

Angela White

Endurance International Group

(781) 852-3450

ir@endurance.com

Press Contact:

Kristen Andrews

Endurance International Group

(781) 482-5809

press@endurance.com

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Endurance International Group Holdings, Inc.

Consolidated Balance Sheets

(unaudited)

(in thousands, except share and per share amounts)

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Endurance International Group Holdings, Inc.

Consolidated Statements of Operations and Comprehensive Loss

(unaudited)

(in thousands, except share and per share amounts)

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Endurance International Group Holdings, Inc.

Consolidated Statements of Cash Flows

(unaudited)

(in thousands)

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GAAP to Non-GAAP reconciliation – Adjusted EBITDA

The following table presents a reconciliation of net income (loss) calculated in accordance with GAAP to adjusted EBITDA (all data in thousands):

GAAP to Non-GAAP reconciliation – Free Cash Flow

The following table reflects the reconciliation of cash flow from operations to free cash flow (“FCF”) (all data in thousands):

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Average Revenue Per Subscriber – Calculation and Segment Detail

We present our financial results in two segments. Our web presence segment is our historical business before the acquisition of Constant Contact, and includes primarily our web hosting products, domains, website builders and related add-on products. Our email marketing segment consists of the Constant Contact business, including email marketing, event management, survey tools and the SinglePlatform digital storefront service.

The following table presents the calculation of ARPS, on a consolidated basis and by segment (all data in thousands, except ARPS data):

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The following table presents revenue, gross profit, and a reconciliation by segment of net income (loss) calculated in accordance with GAAP to adjusted EBITDA (all data in thousands):

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GAAP to Non-GAAP Reconciliation of Fiscal Year 2017 Guidance (as of October 31, 2017) – Adjusted EBITDA

The following table reflects the reconciliation of fiscal year 2017 estimated net loss calculated in accordance with GAAP to fiscal year 2017 guidance for adjusted EBITDA (i.e. assuming an increase of approximately 18% from 2016 adjusted EBITDA as reported). All figures shown are approximate.

GAAP to Non-GAAP Reconciliation of Fiscal Year 2017 Guidance (as of October 31, 2017) – Free Cash Flow

The following table reflects the reconciliation of fiscal year 2017 estimated cash flow from operations calculated in accordance with GAAP to fiscal year 2017 guidance for free cash flow. All figures shown are approximate.

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