Description of Business and Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2026
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) and applicable rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. Certain information and disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K, filed with the SEC on February 19, 2026. The condensed consolidated balance sheet as of December 31, 2025, included herein, was derived from the audited financial statements as of that date, but does not include all disclosures, including certain notes required by GAAP on an annual reporting basis. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive (loss) income and cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full year 2026 or any future period.
Principles of Consolidation	Principles of Consolidation The condensed consolidated financial statements include the accounts of Bandwidth Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires the Company to make estimates and judgments that affect the amounts reported in these financial statements and accompanying notes. These estimates in the condensed consolidated financial statements include, but are not limited to, allowance for expected credit losses, reserve for sales credits, recoverability of long lived and intangible assets, fair value of acquired intangible assets and goodwill, discount rates used in the valuation of right-of-use assets and lease liabilities, the fair value of the liability of the Company’s Convertible Notes (as defined herein), estimated period of benefit, valuation allowances on deferred tax assets, certain accrued expenses and contingencies. Although the Company believes that the estimates it uses are reasonable, due to the inherent uncertainty involved in making these estimates, actual results reported in future periods could differ from those estimates.
Marketable Securities	Marketable Securities The Company classifies marketable securities as available-for-sale at the time of purchase and reevaluates such classification as of each balance sheet date. The Company may sell these securities at any time for use in current operations even if they have not yet reached maturity. As a result, the Company classifies investments with maturities greater than 90 days as marketable securities in the accompanying condensed consolidated balance sheets. The Company evaluates its investments to assess whether the amortized cost basis is in excess of estimated fair value and determines what amount of that difference, if any, is caused by expected credit losses. Allowance for credit losses is recognized as a charge in other (expense) income, net on the condensed consolidated statements of operations, and any remaining unrealized losses are included in accumulated other comprehensive loss on the condensed consolidated balance sheets.
Accounts Receivable	Accounts Receivable and Current Expected Credit Losses Accounts receivable are stated at realizable value, net of allowance for expected credit losses. The allowance for expected credit losses is based on management’s assessment of the collectability of its customer accounts. The Company regularly reviews the composition of the accounts receivable aging, historical credit losses, changes in payment patterns, customer creditworthiness, current economic trends, and reasonable and supportable forecasts about the future. Relevant risk characteristics include customer size and historical loss patterns. Management has evaluated the expected credit losses related to trade accounts receivable and determined that an allowance of approximately $0.6 million and $0.5 million for uncollectible accounts and customer balances that are disputed was required as of June 30, 2026 and December 31, 2025, respectively. Refer to Note 3, “Financial Statement Components” to these condensed consolidated financial statements, for a rollforward of the components of the allowance for the three and six months ended June 30, 2026 and 2025. The Company includes unbilled receivables in its accounts receivable balance. Generally, these receivables represent earned revenue from services provided to customers, which will be billed in the next billing cycle.
Current Expected Credit Losses	Accounts Receivable and Current Expected Credit Losses Accounts receivable are stated at realizable value, net of allowance for expected credit losses. The allowance for expected credit losses is based on management’s assessment of the collectability of its customer accounts. The Company regularly reviews the composition of the accounts receivable aging, historical credit losses, changes in payment patterns, customer creditworthiness, current economic trends, and reasonable and supportable forecasts about the future. Relevant risk characteristics include customer size and historical loss patterns. Management has evaluated the expected credit losses related to trade accounts receivable and determined that an allowance of approximately $0.6 million and $0.5 million for uncollectible accounts and customer balances that are disputed was required as of June 30, 2026 and December 31, 2025, respectively. Refer to Note 3, “Financial Statement Components” to these condensed consolidated financial statements, for a rollforward of the components of the allowance for the three and six months ended June 30, 2026 and 2025. The Company includes unbilled receivables in its accounts receivable balance. Generally, these receivables represent earned revenue from services provided to customers, which will be billed in the next billing cycle.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents, marketable securities and trade accounts receivable. The Company maintains its cash, cash equivalents and marketable securities with high credit-quality financial institutions. Certain balances held by such financial institutions exceed insured limits. With regard to customers, credit evaluation and account monitoring procedures are used to minimize the risk of loss. The Company believes that no additional credit risk beyond amounts provided for by the allowance for expected credit losses are inherent in accounts receivable.
Recently Adopted Accounting Standards and Recent Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Standards In November 2024, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2024-04, Debt—Debt with Conversion and Other Options (Subtopic 470-20): Induced Conversions of Convertible Debt Instruments (“ASU 2024-04”), which provides additional guidance to stakeholders about how to determine whether a settlement of convertible debt (particularly, cash convertible instruments) at terms that differ from the original conversion terms should be accounted for under the induced conversion or extinguishment guidance. The Company adopted ASU 2024-04 effective January 1, 2026 and applied the guidance prospectively. The adoption had no impact on the Company’s financial position or results of operations. In July 2025, the FASB issued ASU 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets (“ASU 2025-05”), which provides a practical expedient for the estimation of expected credit losses for current accounts receivable and current contract assets under ASC 606. The practical expedient election assumes that current conditions as of the balance sheet date do not change for the remaining life of the asset. The Company adopted ASU 2025-05 effective January 1, 2026 and elected the practical expedient. ASU 2025-05 did not have a material impact on the Company's financial position or results of operations. Recent Accounting Pronouncements Not Yet Adopted In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses (“ASU 2024-03”), which requires public entities to disclose disaggregated information about certain costs and expenses on an interim and annual basis. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027, with the option to apply the guidance prospectively or retrospectively. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2024-03 on its consolidated financial statements. In September 2025, the FASB issued ASU 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software (“ASU 2025-06”), which amends certain aspects of the accounting for and disclosure of software costs under ASC 350-40. The guidance removes all references to project stages throughout ASC 350-40 and clarifies the threshold entities apply to begin capitalizing costs. ASU 2025-06 is effective for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods, with the option to apply the guidance prospectively, retrospectively, or via a modified prospective transition method. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2025-06 on its consolidated financial statements.
Fair Value of Financial Instruments	The Company uses a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires use of observable inputs when available, and to minimize the use of unobservable inputs when determining fair value. The three tiers are defined as follows: •Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities; •Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and •Level 3. Unobservable inputs for which there is little or no market data, which requires the Company to develop its own assumptions. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate fair value as of June 30, 2026 and December 31, 2025 because of the relatively short duration of these instruments. Marketable securities consist of time deposits and commercial paper not otherwise classified as cash equivalents. All marketable securities are considered to be available-for-sale and are recorded at their estimated fair values. Unrealized gains and losses for available-for-sale securities are recorded in accumulated other comprehensive loss.

Description of Business and Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2026

The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) and applicable rules and regulations of the U.S. Securities and Exchange Commission (the “SEC”) regarding interim financial reporting. Certain information and disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K, filed with the SEC on February 19, 2026.

The condensed consolidated balance sheet as of December 31, 2025, included herein, was derived from the audited financial statements as of that date, but does not include all disclosures, including certain notes required by GAAP on an annual reporting basis.

In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive (loss) income and cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full year 2026 or any future period.

Principles of Consolidation

The condensed consolidated financial statements include the accounts of Bandwidth Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires the Company to make estimates and judgments that affect the amounts reported in these financial statements and accompanying notes. These estimates in the condensed consolidated financial statements include, but are not limited to, allowance for expected credit losses, reserve for sales credits, recoverability of long lived and intangible assets, fair value of acquired intangible assets and goodwill, discount rates used in the valuation of right-of-use assets and lease liabilities, the fair value of the liability of the Company’s Convertible Notes (as defined herein), estimated period of benefit, valuation allowances on deferred tax assets, certain accrued expenses and contingencies. Although the Company believes that the estimates it uses are reasonable, due to the inherent uncertainty involved in making these estimates, actual results reported in future periods could differ from those estimates.

Marketable Securities

The Company classifies marketable securities as available-for-sale at the time of purchase and reevaluates such classification as of each balance sheet date. The Company may sell these securities at any time for use in current operations even if they have not yet reached maturity. As a result, the Company classifies investments with maturities greater than 90 days as marketable securities in the accompanying condensed consolidated balance sheets. The Company evaluates its investments to assess whether the amortized cost basis is in excess of estimated fair value and determines what amount of that difference, if any, is caused by expected credit losses. Allowance for credit losses is recognized as a charge in other (expense) income, net on the condensed consolidated statements of operations, and any remaining unrealized losses are included in accumulated other comprehensive loss on the condensed consolidated balance sheets.

Accounts Receivable

Accounts Receivable and Current Expected Credit Losses

Accounts receivable are stated at realizable value, net of allowance for expected credit losses. The allowance for expected credit losses is based on management’s assessment of the collectability of its customer accounts. The Company regularly reviews the composition of the accounts receivable aging, historical credit losses, changes in payment patterns, customer creditworthiness, current economic trends, and reasonable and supportable forecasts about the future. Relevant risk characteristics include customer size and historical loss patterns. Management has evaluated the expected credit losses related to trade accounts receivable and determined that an allowance of approximately $0.6 million and $0.5 million for uncollectible accounts and customer balances that are disputed was required as of June 30, 2026 and December 31, 2025, respectively. Refer to Note 3, “Financial Statement Components” to these condensed consolidated financial statements, for a rollforward of the components of the allowance for the three and six months ended June 30, 2026 and 2025.

The Company includes unbilled receivables in its accounts receivable balance. Generally, these receivables represent earned revenue from services provided to customers, which will be billed in the next billing cycle.

Current Expected Credit Losses

Accounts Receivable and Current Expected Credit Losses

Concentration of Credit Risk

Financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents, marketable securities and trade accounts receivable. The Company maintains its cash, cash equivalents and marketable securities with high credit-quality financial institutions. Certain balances held by such financial institutions exceed insured limits.

With regard to customers, credit evaluation and account monitoring procedures are used to minimize the risk of loss. The Company believes that no additional credit risk beyond amounts provided for by the allowance for expected credit losses are inherent in accounts receivable.

Recently Adopted Accounting Standards and Recent Accounting Pronouncements Not Yet Adopted

Recently Adopted Accounting Standards

In November 2024, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2024-04, Debt—Debt with Conversion and Other Options (Subtopic 470-20): Induced Conversions of Convertible Debt Instruments (“ASU 2024-04”), which provides additional guidance to stakeholders about how to determine whether a settlement of convertible debt (particularly, cash convertible instruments) at terms that differ from the original conversion terms should be accounted for under the induced conversion or extinguishment guidance. The Company adopted ASU 2024-04 effective January 1, 2026 and applied the guidance prospectively. The adoption had no impact on the Company’s financial position or results of operations.

In July 2025, the FASB issued ASU 2025-05, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets (“ASU 2025-05”), which provides a practical expedient for the estimation of expected credit losses for current accounts receivable and current contract assets under ASC 606. The practical expedient election assumes that current conditions as of the balance sheet date do not change for the remaining life of the asset. The Company adopted ASU 2025-05 effective January 1, 2026 and elected the practical expedient. ASU 2025-05 did not have a material impact on the Company's financial position or results of operations.

Recent Accounting Pronouncements Not Yet Adopted

In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses (“ASU 2024-03”), which requires public entities to disclose disaggregated information about certain costs and expenses on an interim and annual basis. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027, with the option to apply the guidance prospectively or retrospectively. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2024-03 on its consolidated financial statements.

In September 2025, the FASB issued ASU 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software (“ASU 2025-06”), which amends certain aspects of the accounting for and disclosure of software costs under ASC 350-40. The guidance removes all references to project stages throughout ASC 350-40 and clarifies the threshold entities apply to begin capitalizing costs. ASU 2025-06 is effective for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods, with the option to apply the guidance prospectively, retrospectively, or via a modified prospective transition method. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2025-06 on its consolidated financial statements.

Fair Value of Financial Instruments

The Company uses a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires use of observable inputs when available, and to minimize the use of unobservable inputs when determining fair value. The three tiers are defined as follows:

•Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities;

•Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and

•Level 3. Unobservable inputs for which there is little or no market data, which requires the Company to develop its own assumptions.

A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate fair value as of June 30, 2026 and December 31, 2025 because of the relatively short duration of these instruments. Marketable securities consist of time deposits and commercial paper not otherwise classified as cash equivalents. All marketable securities are considered to be available-for-sale and are recorded at their estimated fair values. Unrealized gains and losses for available-for-sale securities are recorded in accumulated other comprehensive loss.