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Calculation of Basic and Diluted Net Loss Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Fixed coverage charge ratio Line Of Credit Facility, Fixed Coverage Charge Ratio Line Of Credit Facility, Fixed Coverage Charge Ratio Beginning balance Ending balance Accounts Receivable, Allowance for Credit Loss, Current Accrued compensation Increase Decrease In Accrued Compensation Increase decrease in Accrued compensation. 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Plan Name Plan Name [Axis] Individual Customer D Individual Customer D [Member] Individual Customer D Equity Components Equity Components [Axis] Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] Award Timing Method Award Timing Method [Text Block] Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Class A Units Members Equity Class A Units [Member] Members equity class A units. 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Unrecognized stock-based compensation expected to be recognized Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Current assets: Assets, Current [Abstract] Goodwill Goodwill Supplier One Supplier One [Member] Supplier one. Repurchase of stock related to tax withholdings on vested equity awards Payment, Tax Withholding, Share-Based Payment Arrangement Authorized amount, stock repurchase program Share Repurchase Program, Authorized, Amount Treasury stock, shares (shares) Beginning balance, treasury stock (shares) Ending balance, treasury stock (shares) Treasury Stock, Common, Shares Summary Ownership of Viant Technology LLC Schedule Of Noncontrolling Ownership Interests Table [Table Text Block] Schedule of noncontrolling ownership interests. Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Employee Stock Option Share-Based Payment Arrangement, Option [Member] Short-term lease cost Short-Term Lease, Cost Vested (USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Depreciation Depreciation 2026 Lessee, Operating Lease, Liability, to be Paid, Year One Supplier Three Supplier Three [Member] Supplier Three Preferred stock, shares outstanding (shares) Preferred Stock, Shares Outstanding Name of each exchange on which registered Security Exchange Name Debt instrument, basis spread on variable rate plus margin Debt Instrument, Basis Spread on Variable Rate Exchange basis Continuing Members, Exchange Basis Continuing Members, Exchange Basis Award Type Award Type [Axis] Cumulative Effect, Period of Adoption, Adjustment Cumulative Effect, Period of Adoption, Adjustment [Member] Exercised (USD per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Property, equipment, and software, net Total property, equipment, and software, net Property, Plant and Equipment, Net Total liabilities Liabilities Noncontrolling interests Equity, Attributable to Noncontrolling Interest Common stock, par value (USD per share) Common Stock, Par or Stated Value Per Share Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] LTIP Long Term Incentive Plan [Member] Long Term Incentive Plan. Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Remaining Weighted-Average Useful Life (years) Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life Revolving Credit Facility Revolving Credit Facility [Member] Expiration Date Trading Arrangement Expiration Date Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Current portion of operating lease liabilities Less: Operating lease liabilities, current Operating Lease, Liability, Current Total Shareholder Return Amount Total Shareholder Return Amount Common stock, shares issued (shares) Common Stock, Shares, Issued Entity Entity [Domain] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Senior secured revolving credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Concentration risk, percentage Concentration Risk, Percentage Loss before income taxes Income (Loss), Including Portion Attributable to Noncontrolling Interest, before Tax Computer equipment Computer Equipment [Member] Class of Treasury Stock Class of Treasury Stock [Table Text Block] Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Less: Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Subsequent Event [Line Items] Subsequent Event [Line Items] Total property, equipment, and software Property, Plant and Equipment, Gross Issuance of Class A common stock in connection with exercise of stock options (shares) Exercised (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Common stock, shares authorized (shares) Common Stock, Shares Authorized Cash paid for acquisitions Payments to Acquire Businesses, Net of Cash Acquired Diluted (shares) Weighted-average shares of Class A common stock outstanding—diluted (shares) Weighted Average Number of Shares Outstanding, Diluted MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Remainder of 2025 Finite-Lived Intangible Asset, Expected Amortization, Remainder of Fiscal Year Numerator Net Income (Loss) Available to Common Stockholders, Basic [Abstract] Total stockholders’ equity attributable to Viant Technology Inc. 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Viant Technology Inc [Member] Viant Technology Inc. Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations Vested (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Summary of Estimated Future Amortization of Intangible Assets Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Risk-free interest rate Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Subsequent Event [Table] Subsequent Event [Table] Members equity units received in exchange of units (shares) Members Equity Units Received During Period Conversion Of Units Members equity units received during period conversion of units. 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Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Over-time revenue Transferred over Time [Member] Money market funds Money Market Funds, at Carrying Value Supplier Concentration Risk Supplier Concentration Risk [Member] Non-PEO NEO Non-PEO NEO [Member] Additional Paid-In Capital Additional Paid-in Capital [Member] Allocation of equity to noncontrolling interests Stock Issued During Period Value Allocation Of Equity To Non Controlling Interests Stock issued during period, value, allocation of equity to non-controlling interests. 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Minority Interest [Table] Noncontrolling Interest [Table] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Legal Entity Legal Entity [Axis] Interest income, net Interest Income (Expense), Nonoperating Finite-Lived Intangible Assets, Major Class Name Finite-Lived Intangible Assets, Major Class Name [Domain] Repurchase of stock related to the stock repurchase program Payment, Tax Withholding, Share-Based Payment Arrangement, Share Repurchase Program Payment, Tax Withholding, Share-Based Payment Arrangement, Share Repurchase Program Customer One Customer One [Member] Customer One Payments to acquire units Payments To Acquire Member Units Payments to acquire member units. Operating lease assets obtained in exchange for operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Underlying Security Market Price Change Underlying Security Market Price Change, Percent Individual: Individual [Axis] Canceled (USD per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price Expected term (in years) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term Entity Address, State or Province Entity Address, State or Province Property Plant And Equipment [Line Items] Property, Plant and Equipment [Line Items] Viant Technology LLC Viant Technology L L C [Member] Viant Technology LLC. Statement [Line Items] Statement [Line Items] Decrease in the additional-paid-in-capital of Viant Technology Inc. resulting from ownership changes in Viant Technology LLC Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Ownership Changes Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Changes, Ownership Changes Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Contractual obligation, to be paid 2025 Contractual Obligation, to be Paid, Year Two Schedule of Major Classes of Property, Equipment and Software Property, Plant and Equipment [Table Text Block] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Thereafter Finite-Lived Intangible Asset, Expected Amortization, After Year Four Finite-Lived Intangible Asset, Expected Amortization, After Year Four Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Weighted-Average Grant-Date Fair Value of RSUs outstanding, beginning balance (USD per share) Weighted-Average Grant-Date Fair Value of RSUs outstanding, ending balance (USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Liabilities and stockholders’ equity Liabilities and Equity [Abstract] Vested and exercisable (USD per share) Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Exercisable Weighted Average Exercise Price Share based compensation arrangement by share based payment award options vested and exercisable weighted average exercise price. Minimum Minimum [Member] Restatement Determination Date Restatement Determination Date Payment of offering costs Payments for Repurchase of Initial Public Offering Adoption Date Trading Arrangement Adoption Date Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Schedule Of Property Plant And Equipment [Table] Property, Plant and Equipment [Table] Weighted-Average Exercise Price of outstanding, beginning balance (USD per share) Weighted-Average Exercise Price of outstanding, ending balance (USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price Operating lease assets, net Operating Lease, Right-of-Use Asset Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Number of Options outstanding, beginning balance (shares) Number of Options outstanding, ending balance (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Remaining lease term, short-term leases Lessee, Operating Lease, Remaining Lease Term, Short-Term Leases Lessee, Operating Lease, Remaining Lease Term, Short-Term Leases Provision for doubtful accounts Provision for doubtful accounts Accounts Receivable, Credit Loss Expense (Reversal) Segments [Axis] Segments [Axis] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Exchange units for shares of common stock (shares) Exchange Units For Shares Of Common Stock Exchange units for shares of common stock. U.S. statutory federal income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Contractual obligations, remainder of 2023 Contractual Obligation, to be Paid, Remainder of Fiscal Year Exercise Price Award Exercise Price Chris Vanderhook [Member] Chris Vanderhook Loss Per Share Earnings Per Share [Text Block] Arrangement Duration Trading Arrangement Duration Subsequent Event Subsequent Event [Member] Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Operating expenses: Costs and Expenses [Abstract] Less: Imputed interest Lessee Operating Lease Liability Imputed Interest Lessee operating lease liability imputed interest. Stockholders’ equity Equity, Attributable to Parent [Abstract] Granted (USD per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted-Average Remaining Contractual Term of Options, Vested and exercisable Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Exercisable Weighted Average Remaining Contractual Term Share based compensation arrangement by share based payment award options vested and exercisable weighted average remaining contractual term. Units Owned (shares) Number Of Units Owned Number of units owned. Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Expected Duration of Greater Than One Year Long-Term Contract with Customer [Member] Segments [Domain] Segments [Domain] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] 2029 Finite-Lived Intangible Asset, Expected Amortization, Year Four All Individuals All Individuals [Member] Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation and Significant Accounting Policies [Text Block] Trademarks/tradenames Trademarks and Trade Names [Member] Vested and exercisable (shares) Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Exercisable Number Of Shares Share based compensation arrangement by share based payment award options vested and exercisable number of shares. PEO PEO [Member] Variable Rate Variable Rate [Axis] Contract with Customer, Duration Contract with Customer, Duration [Domain] Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Name Trading Arrangement, Individual Name Other expense, net Other Nonoperating Income (Expense) Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Change from net loss attributable to Viant Technology Inc. and transfers to noncontrolling interests Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Change Due to Net Income Attributable to Parent and Effects of Changes, Net Long-Lived Tangible Asset Long-Lived Tangible Asset [Axis] Operating leases for office space remaining lease terms Lessee, Operating Lease, Remaining Lease Term Schedule of Depreciation Schedule Of Depreciation Expense Table [Table Text Block] Schedule of depreciation expense. Capitalized software development costs Payments to Develop Software Facility fee for undrawn amounts Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Schedule of Concentration of Credit Risk Schedules of Concentration of Risk, by Risk Factor [Table Text Block] Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Lender Name Lender Name [Axis] Schedule Of Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Table] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table] Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Related Party [Domain] Related and Nonrelated Parties [Domain] Beginning balance (shares) Ending balance (shares) Shares, Outstanding Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Members Equity Class B Units Members Equity Class B Units [Member] Members Equity Class B Units Local Phone Number Local Phone Number Supplier Supplier [Axis] Nature Of Operations [Line Items] Nature Of Operations [Line Items] Nature of Operations. 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