Organization	9 Months Ended
Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	1. Organization Description of the Business RAPT Therapeutics, Inc. (“RAPT” or the “Company”) is a clinical-stage, immunology-based biopharmaceutical company focused on discovering, developing and commercializing oral small molecule therapies for patients with significant unmet needs in oncology and inflammatory diseases. Utilizing its proprietary drug discovery and development engine, the Company develops highly selective small molecules that are designed to modulate the critical immune responses underlying these diseases. The Company is located in South San Francisco, California. Equity Financings In June 2021, pursuant to the shelf registration statement on Form S-3 that was declared effective by the Securities and Exchange Commission (“SEC”) on November 16, 2020, the Company completed a public offering (“2021 Public Offering”) of 4,356,060 shares of common stock, including 568,181 shares of the common stock issued in connection with the exercise of the over-allotment option by the underwriters of their over-allotment option, at a public offering price of $33.00 per share. The Company received approximately $134.6 million in net proceeds from the 2021 Public Offering, after deducting underwriting discounts and other offering-related costs. During the nine months ended September 30, 2021, the Company sold 214,971 shares of common stock in “at the market” offerings pursuant to a Controlled Equity Offering^SM Sales Agreement with Cantor Fitzgerald & Co. and Stifel, Nicolaus & Company, Incorporated (the “ATM Sales Agreement”), for net proceeds of $4.7 million after deducting commissions and other offering related costs. As of September 30, 2021, there was up to $90.9 million available for future issuance of shares of common stock under the ATM Sales Agreement.

Organization

9 Months Ended

Sep. 30, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

1. Organization

Description of the Business

RAPT Therapeutics, Inc. (“RAPT” or the “Company”) is a clinical-stage, immunology-based biopharmaceutical company focused on discovering, developing and commercializing oral small molecule therapies for patients with significant unmet needs in oncology and inflammatory diseases. Utilizing its proprietary drug discovery and development engine, the Company develops highly selective small molecules that are designed to modulate the critical immune responses underlying these diseases.

The Company is located in South San Francisco, California.

Equity Financings

In June 2021, pursuant to the shelf registration statement on Form S-3 that was declared effective by the Securities and Exchange Commission (“SEC”) on November 16, 2020, the Company completed a public offering (“2021 Public Offering”) of 4,356,060 shares of common stock, including 568,181 shares of the common stock issued in connection with the exercise of the over-allotment option by the underwriters of their over-allotment option, at a public offering price of $33.00 per share. The Company received approximately $134.6 million in net proceeds from the 2021 Public Offering, after deducting underwriting discounts and other offering-related costs.

During the nine months ended September 30, 2021, the Company sold 214,971 shares of common stock in “at the market” offerings pursuant to a Controlled Equity Offering^SM Sales Agreement with Cantor Fitzgerald & Co. and Stifel, Nicolaus & Company, Incorporated (the “ATM Sales Agreement”), for net proceeds of $4.7 million after deducting commissions and other offering related costs. As of September 30, 2021, there was up to $90.9 million available for future issuance of shares of common stock under the ATM Sales Agreement.