Bandwidth Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

For the fiscal year ended December 31, 2025

OR

For the transition period from to

Commission File Number:001-38285

(Exact name of registrant as specified in its charter)

2230 Bandmate Way

Raleigh, NC 27607

(Address of principal executive offices) (Zip Code)

(800) 808-5150

(Registrant’s telephone number, including area code)

Securities Registered Pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☐ No x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes ☐ No x

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes x No ☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes x No☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.☐

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☒

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b). ☐

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes☐ No☒

The aggregate market value of the voting and non-voting common stock held by non-affiliates of the registrant as of June 30, 2025, the last business day of the registrant’s most recently completed second fiscal quarter, was $430.7 million based upon the closing price reported for such date on the NASDAQ Global Select Market.

As of February 13, 2026,29,428,894 shares of the registrant’s Class A common stock and 1,958,028 shares of registrant’s Class B common stock were outstanding, respectively.

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the registrant’s Definitive Proxy Statement for the 2026 Annual Meeting of Stockholders are incorporated herein by reference in Part II and Part III of this Annual Report on Form 10-K to the extent stated herein. Such Definitive Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, 2025.

Special Note Regarding Forward-Looking Statements

This Annual Report on Form 10-K contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”) and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”). All statements contained in this Annual Report on Form 10-K, other than statements of historical fact, are forward-looking statements. Forward-looking statements generally can be identified by the words “may,” “will,” “expect,” “believe,” “anticipate,” “intend,” “could,” “would,” “project,” “plan,” “estimate,” or “continue,” or the negative of these words or other similar terms or expressions that concern our expectations strategy, plans or intentions. Forward-looking statements contained in this Annual Report on Form 10-K include, but are not limited to, statements about:

•our beliefs regarding the impact of macroeconomic conditions, including inflationary and/or recessionary pressures, on our business and financial condition;

•our ability to attract and retain customers, including large enterprises;

•our approach to identifying, attracting and keeping new and existing customers, as well as our expectations regarding customer turnover;

•our beliefs regarding network traffic growth and other trends related to the usage of our products and services;

•the impact of our customers’ violation of applicable laws, our policies or other misuse of our platform;

•our ability to successfully defend our network, systems and data against ever-evolving cybersecurity threats, including denial-of-service and ransomware attacks;

•our expectations regarding revenue, costs, expenses, gross margin, net retention rate, Adjusted EBITDA, non-generally accepted accounting principles in the United States of America (“GAAP”) net income and capital expenditures;

•our beliefs regarding the growth of our business and how that impacts our liquidity and capital resources requirements;

•our expectations about the impact of public health epidemics, such as COVID-19, or natural disasters on the global economy and our business, results of operations and financial condition;

•the sufficiency of our cash and cash equivalents to meet our liquidity needs;

•our ability to attract, train, and retain qualified employees and key personnel;

•our beliefs regarding the expense and productivity of and competition for our sales force;

•our expectations regarding headcount;

•our ability to maintain and benefit from our corporate culture;

•our plans to further invest in and grow our business, including international offerings, and our ability to effectively manage our growth and associated investments;

•our ability to introduce new products and services and enhance existing products and services;

•our ability to successfully integrate and benefit from any strategic acquisitions, including our acquisition of Voxbone, or future strategic acquisitions or investments;

•our ability to effectively manage our international operations and expansion;

•our ability to compete successfully against current and future competitors;

•the evolution of technology affecting our products, services and markets;

•the impact of certain new accounting standards and guidance, as well as the time and cost of continued compliance with existing rules and standards;

•our beliefs regarding the use of Non-GAAP financial measures;

•our ability to comply with modified or new industry standards, laws and regulations applicable to our products, services and business, including the General Data Protection Regulation (“GDPR”), the California Consumer Privacy Act of 2018 and other privacy regulations that may be implemented in the future, and Secure Telephone Identity Revisited and Signature-based Handling of Asserted Information Using toKENs (“STIR/SHAKEN”), and other robocalling prevention and anti-spam standards and increased costs associated with such compliance;

•our ability to manage fees that have been or may be instituted by network providers that increase our costs;

•our ability to maintain, protect and enhance our intellectual property;

•our expectations regarding litigation and other pending or potential disputes;

•our ability to service the interest on our Convertible Notes (as defined herein) and repay such Convertible Notes, to the extent required; and

•other risks related to our indebtedness.

We caution you that the foregoing list may not contain all the forward-looking statements made in this Annual Report on Form 10-K.

You should not rely upon forward-looking statements as predictions of future events. We have based the forward-looking statements contained in this Annual Report on Form 10-K primarily on our current expectations and projections about future events and trends that we believe may affect our business, financial condition, results of operations and prospects. The outcome of the events described in these forward-looking statements is subject to risks, uncertainties and other factors described in the section titled “Risk Factors” and elsewhere in this Annual Report on Form 10-K. Moreover, we operate in a very competitive and rapidly changing environment. New risks and uncertainties emerge from time to time and it is not possible for us to predict all risks and uncertainties that could have an impact on the forward-looking statements contained in this Annual Report on Form 10-K. We cannot assure you that the results, events and circumstances reflected in the forward-looking statements will be achieved or occur, and actual results, events or circumstances could differ materially from those described in the forward-looking statements.

The forward-looking statements made in this Annual Report on Form 10-K relate only to events as of the date on which the statements are made. We undertake no obligation to update any forward-looking statements made in this Annual Report on Form 10-K to reflect events or circumstances after the date of this Annual Report on Form 10-K or to reflect new information or the occurrence of unanticipated events, except as required by law. We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements and you should not place undue reliance on our forward-looking statements. Our forward-looking statements do not reflect the potential impact of any future acquisitions, mergers, dispositions, joint ventures or investments we may make.

Risk Factors Summary

The following is a summary of the principal risks that could adversely affect our business, results of operations and financial condition.

Risks Related to Our Business

•Our growth and financial health are subject to a number of economic risks.

•Government shutdowns or delays in federal agency operations, subject us to a number of risks.

•Nearly all of our operating cash is held in financial institution accounts that are not FDIC-insured.

•The market in which we participate is highly competitive, and we may not compete effectively.

•We may not be able to attract new customers in a cost-effective manner.

•The market for some of our services is new and unproven, and may decline or experience limited growth.

•Our ability to meet our goals for revenue growth, cash flow and operating performance depends on customers increasing their use of our services.

•We may not be able to increase the revenue that we derive from enterprises.

•We may not be able to develop service enhancements or new services that achieve market acceptance.

•We use AI in our business, and challenges in managing it could adversely affect our results of operations.

•As we expand, we may experience difficulty maintaining our corporate culture and operational infrastructure.

•We have grown rapidly, and may not be able to manage the growth effectively.

•Our pricing and billing systems are complex and errors could adversely affect our results of operations.

•We must continue to develop effective systems to support our business.

•We may not be able to maintain and enhance our brand and increase market awareness.

•Failure to deliver high-quality support may adversely affect our customer relationships.

•We operate internationally, which exposes us to incremental risks.

•A significant portion of our revenue is concentrated in a limited number of large customers.

•Cyberattacks or breaches of our systems or third-party systems we rely on could disrupt our services and harm our business.

•We are currently subject to litigation, including litigation related to taxes and charges associated with our provision of 911 services.

•Customer misuse of our services and software could result in litigation and/or regulatory enforcement actions and harm our business and reputation.

•We are subject to litigation in the ordinary course of business, which may harm our business.

•The communications industry faces significant regulatory uncertainties globally.

•The effects of evolving regulation of Internet Protocol (“IP”)-based service providers are unknown.

•Expanded state and federal oversight and enforcement may increase our compliance and litigation risk.

•We must obtain and maintain numerous licenses and permits to operate our network.

•Evolving technical standards could increase business costs for existing and future products.

•Regulatory violations could limit our operations or impose costly compliance obligations.

•Our business is subject to complex and evolving laws, commercial standards, contractual obligations and other requirements regarding privacy and data protection.

•Our business may be harmed if we cannot obtain or retain numbering resources.

•We may be exposed to liabilities under anti-corruption, export control and economic sanction regulations.

•Third-party intellectual property rights could prevent us from using technologies needed to provide our services.

•Use of open source software could negatively affect our ability to sell our services and subject us to litigation.

•Indemnity provisions in various agreements potentially expose us to substantial liability.

•We may fail to protect our internally developed systems, technology and software and our intellectual property.

•We may be liable for the information that content owners or distributors distribute over our network.

•Third parties may use our services to commit fraud or steal our services.

•Our customers may choose to discontinue use of Voice over Internet Protocol (“VoIP”)-based services and revert to traditional network service providers.

•We may lose customers if our platform or network fails or is disrupted.

•Defects or errors in our services could harm our business.

•If our emergency services do not function properly, we may be exposed to significant liability.

•Termination of relationships with key suppliers could cause delay and additional costs.

•Supply chain interruptions or cyber-attacks aimed at third parties we work with could harm our business.

•Our customer churn rate may increase.

•The prices for some of our services have decreased in the past and may do so again in the future.

•The need to obtain additional IP circuits or interconnect with other networks could increase our costs.

•The loss of any member of our senior management team or key employees could harm our business.

•If we are unable to hire, retain and motivate qualified personnel, our business will suffer.

•We could be subject to additional tax liabilities for historic and future sales, use and similar taxes.

•Our global operations and legal entity structure subject us to potentially adverse income tax consequences.

•Use of net operating loss and tax credit carryforwards to offset future taxable income may be limited.

•If we redeem or repurchase shares of our stock in the future, we could be subject to an excise tax.

•Our estimates or judgments relating to our critical accounting policies may prove to be incorrect.

•We may not maintain an effective system of disclosure controls and internal control over financial reporting.

•If our goodwill or intangible assets become impaired, we may be required to record a significant charge.

•Foreign currency exchange rate fluctuations may harm our business.

•Natural disasters, pandemics, power outages, terrorist attacks, acts of war, civilian unrest and similar events could harm our business.

•We may acquire other businesses, which may divert our management’s attention and impact our stock price.

Risks Related to the Convertible Notes

•Servicing our future indebtedness may require a significant amount of cash, which we may not have.

•We may not have the ability to raise the funds necessary for cash settlement of the Convertible Notes.

•The capped call transactions may affect the value of the Convertible Notes and our Class A common stock.

•We are subject to counterparty risk with respect to the Capped Calls.

Risks Related to Ownership of Our Class A Common Stock

•Our Class A common stock price may be volatile and you could lose all or part of your investment.

•Substantial future sales of shares of our Class A common stock could cause the price of our Class A to decline.

•Our dual class capital structure may be perceived to concentrate voting control.

•We cannot predict the impact our capital structure may have on our stock price.

•Our stock price and trading volume could decline if securities or industry analysts stop covering our Class A Common Stock.

•Anti-takeover provisions in our organizational documents and Delaware law could impair a takeover attempt.

•Our certificate of incorporation and bylaws include super-majority voting provisions.

•Our bylaws provide that Delaware will be the sole and exclusive forum for certain stockholder litigation.

•We may need additional capital in the future and such capital may be limited or unavailable.

•We do not intend to pay dividends for the foreseeable future.