Organization and Description of Business	9 Months Ended
Oct. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business MongoDB, Inc. (“MongoDB” or the “Company”) was originally incorporated in the state of Delaware in November 2007 under the name 10Gen, Inc. In August 2013, the Company changed its name to MongoDB, Inc. The Company is headquartered in New York City. The Company develops and sells subscriptions to a modern, general purpose database platform that was built to run applications at scale across a broad range of use cases in the cloud, on-premise or in a hybrid environment. The Company designed its platform to address the performance, scalability, flexibility and reliability demands of modern applications while maintaining the core capabilities of legacy databases. In addition to selling its software, the Company provides post-contract support, training, and consulting services for its offerings. The Company’s fiscal year ends January 31. Reverse Stock Split In October 2017, the Company's Board of Directors (the “Board of Directors”) and stockholders approved an amendment to the Company's amended and restated certificate of incorporation effecting a 1-for-2 reverse stock split of the Company's issued and outstanding shares of common stock and accordingly adjusted the conversion rate of the Series A, B, C, D and E redeemable convertible preferred stock to common stock to 1:0.75 and the conversion rate of the Series F redeemable convertible preferred stock to common stock to 1:0.5. The reverse split was effected on October 5, 2017. The par value of the common stock and redeemable convertible preferred stock was not adjusted as a result of the reverse stock split. All issued and outstanding share and per share amounts included in the accompanying unaudited condensed consolidated financial statements have been adjusted to reflect this reverse stock split for all periods presented. Initial Public Offering In October 2017, the Company closed its initial public offering (“IPO”) of 9,200,000 shares of its Class A common stock at an offering price of $24.00 per share, including 1,200,000 shares pursuant to the underwriters’ option to purchase additional shares of the Company’s Class A common stock. The Company received net proceeds of $201.6 million, after deducting underwriting discounts and commissions of $15.5 million and offering expenses of $3.9 million. Immediately prior to the closing of the IPO, all 41,232,762 shares of the Company’s then-outstanding redeemable convertible preferred stock automatically converted into 26,952,887 shares of common stock at their respective conversion ratios and the Company reclassified $346.4 million from temporary equity to Class B common stock and additional paid-in capital on its consolidated balance sheet. Deferred Offering Costs Deferred offering costs of $3.9 million, consisting of legal, accounting and other fees and costs related to the IPO, were reclassified to additional paid-in capital as a reduction of the proceeds upon the closing of the IPO in October 2017. During the nine months ended October 31, 2017, $2.3 million of the deferred offering costs were paid.

Organization and Description of Business

MongoDB, Inc. (“MongoDB” or the “Company”) was originally incorporated in the state of Delaware in November 2007 under the name 10Gen, Inc. In August 2013, the Company changed its name to MongoDB, Inc. The Company is headquartered in New York City. The Company develops and sells subscriptions to a modern, general purpose database platform that was built to run applications at scale across a broad range of use cases in the cloud, on-premise or in a hybrid environment. The Company designed its platform to address the performance, scalability, flexibility and reliability demands of modern applications while maintaining the core capabilities of legacy databases. In addition to selling its software, the Company provides post-contract support, training, and consulting services for its offerings. The Company’s fiscal year ends January 31.

Reverse Stock Split

In October 2017, the Company's Board of Directors (the “Board of Directors”) and stockholders approved an amendment to the Company's amended and restated certificate of incorporation effecting a 1-for-2 reverse stock split of the Company's issued and outstanding shares of common stock and accordingly adjusted the conversion rate of the Series A, B, C, D and E redeemable convertible preferred stock to common stock to 1:0.75 and the conversion rate of the Series F redeemable convertible preferred stock to common stock to 1:0.5. The reverse split was effected on October 5, 2017. The par value of the common stock and redeemable convertible preferred stock was not adjusted as a result of the reverse stock split. All issued and outstanding share and per share amounts included in the accompanying unaudited condensed consolidated financial statements have been adjusted to reflect this reverse stock split for all periods presented.

Initial Public Offering

In October 2017, the Company closed its initial public offering (“IPO”) of 9,200,000 shares of its Class A common stock at an offering price of $24.00 per share, including 1,200,000 shares pursuant to the underwriters’ option to purchase additional shares of the Company’s Class A common stock. The Company received net proceeds of $201.6 million, after deducting underwriting discounts and commissions of $15.5 million and offering expenses of $3.9 million. Immediately prior to the closing of the IPO, all 41,232,762 shares of the Company’s then-outstanding redeemable convertible preferred stock automatically converted into 26,952,887 shares of common stock at their respective conversion ratios and the Company reclassified $346.4 million from temporary equity to Class B common stock and additional paid-in capital on its consolidated balance sheet.

Deferred Offering Costs

Deferred offering costs of $3.9 million, consisting of legal, accounting and other fees and costs related to the IPO, were reclassified to additional paid-in capital as a reduction of the proceeds upon the closing of the IPO in October 2017. During the nine months ended October 31, 2017, $2.3 million of the deferred offering costs were paid.