June 17, 2021 Matthew Cain c/o Couchbase, Inc. Santa Clara, California 95054 Dear Mr. Cain,

Exhibit 10.9

June 17, 2021

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c/o Couchbase, Inc.

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▇▇▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇

Dear ▇▇. ▇▇▇▇,

This letter agreement (the “Agreement”) is entered into between ▇▇▇▇▇▇▇ ▇▇▇▇ (“you”) and Couchbase, Inc. (the “Company” or “we”), effective as of June 17, 2021 (the “Effective Date”), to confirm the terms and conditions of your employment with the Company as of the Effective Date. This Agreement supersedes and replaces any and all employment terms, compensation, or benefits you may have had or to which you may have been entitled prior to the Effective Date.

1.    Title/Position. You will continue to serve as the Company’s President and Chief Executive Officer. You also will continue to report to the Company’s Board of Directors (the “Board”) and will perform the duties and responsibilities customary for such position and such other related duties as are lawfully assigned by the Company’s Chief Executive Officer. By signing this Agreement, you confirm that you continue to have no contractual commitments or other legal obligations that would prohibit you from performing your duties for the Company.

2.    Base Salary. As of the Effective Date, your annual base salary is $450,000, which will be payable, less any applicable withholdings, in accordance with the Company’s normal payroll practices. Your annual base salary will be subject to review and adjustment from time to time by our Board or its Compensation Committee (the “Committee”), as applicable, in its sole discretion.

3.    Annual Bonus. For the Company’s 2022 fiscal year, you will have the opportunity to earn a target annual cash bonus equal to $337,500, subject to the completion of the Company’s initial public offering in the 2022 fiscal year, based on achieving performance objectives established by the Board or Committee, as applicable, in its sole discretion and payable upon achievement of those objectives as determined by the Committee. Unless determined otherwise by the Board or Committee, as applicable, any such bonus will be subject to your continued employment through and until the date of payment. Your annual bonus opportunity and the applicable terms and conditions may be adjusted from time to time by our Board or the Committee, as applicable, in its sole discretion.

4.    Equity Awards. You will be eligible to receive awards of stock options, restricted stock units or other equity awards pursuant to any plans or arrangements the Company may have in effect from time to time. The Board or Committee, as applicable, will determine in its sole discretion whether you will be granted any such equity awards and the terms of any such award in accordance with the terms of any applicable plan or arrangement that may be in effect from time to time. Your equity awards outstanding as of the Effective Date will continue in effect on their existing terms.

5.    Employee Benefits. You will continue to be eligible to participate in the benefit plans and programs established by the Company for its employees from time to time, subject to their applicable terms and conditions, including without limitation any eligibility requirements. The Company reserves the right to modify, amend, suspend or terminate the benefit plans and programs it offers to its employees at any time.

6.    Severance. As of the Effective Date, you will be eligible to enter into, and participate in, the Company’s Change in Control and Severance Policy (the “CIC/Severance Policy”) with the benefits applicable to you based on your position within the Company. The CIC/Severance Policy and the participation agreement under the CIC/Severance Policy that you signed at the same time as this letter specify the severance payments and benefits you may become entitled to receive in connection with certain qualifying terminations of your employment with the Company. These protections supersede all other severance payments and benefits to which you otherwise may be entitled, or may become entitled in the future, under any plan, program or policy that the Company may have in effect from time to time. For purposes of clarification, any severance benefits or arrangements that may have applied to you before the Effective Date no longer will apply and you will have no rights or entitlements under any such plans, programs, agreements or arrangements.

7.    Confidentiality Agreement. As an employee of the Company, you will continue to have access to certain confidential information of the Company and you may, during the course of your employment, develop certain information or inventions that will be the property of the Company. To protect the interests of the Company, your acceptance of this Agreement confirms that the terms of the Employee Inventions Assignment and Confidentiality Agreement you previously signed with the Company (the “Confidentiality Agreement”) still apply.

8.    Arbitration. To ensure the rapid and economical resolution of disputes that may arise in connection with your employment with the Company, you and the Company agree that any and all disputes, claims or causes of action, in law or equity, arising from or relating to the enforcement, breach, performance, or interpretation of this Agreement, your employment, or the termination of your employment, shall be resolved, to the fullest extent permitted by law, by final, binding and confidential arbitration in San Francisco, California conducted by Judicial Arbitration and Mediation Services, Inc. (“JAMS”) or its successor, under the then applicable rules of JAMS. You acknowledge that by agreeing to this arbitration procedure, both you and the Company waive the right to resolve any such dispute through a trial by jury or judge or administrative proceeding. The arbitrator shall: (a) have the authority to compel adequate discovery for the resolution of the dispute and to award such relief as would otherwise be permitted by law; and (b) issue a written arbitration decision including the arbitrator’s essential findings and conclusions and a statement of the award. The arbitrator shall be authorized to award any or all remedies that you or the Company would be entitled to seek in a court of law. The Company shall pay all JAMS’ arbitration fees in excess of those which would be required if the dispute were decided in a court of law. Nothing in this Agreement is intended to prevent either you or the Company from obtaining injunctive relief in court to prevent irreparable harm pending the conclusion of any such arbitration. Notwithstanding the foregoing, you and the Company each have the right to resolve any issue or dispute arising under the Confidentiality Agreement by court action instead of arbitration.

9.    At-Will Employment. This Agreement does not imply any right to your continued employment for any period with the Company or any of its affiliates. Your employment with the Company will continue to be “at will.” It is for no specified term, and may be terminated by you or the Company at any time, with or without cause or advance notice.

10.    Protected Activity Not Prohibited. Nothing in this Agreement or in any other agreement between you and the Company, as applicable, will in any way limit or prohibit you from engaging for a lawful purpose in any Protected Activity. For purposes of this Agreement, “Protected Activity” means filing a charge, complaint, or report with, or otherwise communicating, cooperating, or participating in any investigation or proceeding that may be conducted by, any state, federal, or local governmental agency or commission, including the U.S. Securities and Exchange Commission, the Equal Employment Opportunity Commission, the Occupational Safety and Health Administration, and the National Labor Relations Board (the “Government Agencies”). You understand that in connection with such Protected Activity, you are permitted to disclose documents or other information as permitted by law, and without giving notice to, or receiving authorization from, the Company. Notwithstanding the foregoing, you agree to take all reasonable precautions to prevent any unauthorized use or disclosure of any information that may constitute Company confidential information under the Confidentiality Agreement to any parties other than the Government Agencies. You further understand that “Protected Activity” does not include the disclosure of any Company attorney-client privileged communications. Any language in the Confidentiality Agreement regarding your right to engage in Protected Activity that conflicts with, or is contrary to, this paragraph is superseded by this Agreement. In addition, pursuant to the Defend Trade Secrets Act of 2016, you are notified that an individual will not be held criminally or civilly liable under any federal or state trade secret law for the disclosure of a trade secret that (i) is made in confidence to a federal, state, or local government official (directly or indirectly) or to an attorney solely for the purpose of reporting or investigating a suspected violation of law, or (ii) is made in a complaint or other document filed in a lawsuit or other proceeding, if (and only if) such filing is made under seal. In addition, an individual who files a lawsuit for retaliation by an employer for reporting a suspected violation of law may disclose the trade secret to the individual’s attorney and use the trade secret information in the court proceeding, if the individual files any document containing the trade secret under seal and does not disclose the trade secret, except pursuant to court order.

11.    Miscellaneous. This Agreement, together with the Confidentiality Agreement, the CIC/Severance Policy and any outstanding equity awards granted to you by the Company under its 2008 and/or 2018 Equity Incentive Plan and the applicable award agreements thereunder, constitute the entire agreement between you and the Company regarding

the material terms and conditions of your employment, and they supersede and replace all prior negotiations, representations or agreements between you and the Company. This Agreement may be modified only by a written agreement signed by you and a duly authorized officer of the Company.

[Signature page follows]

To confirm the terms and conditions of your employment with the Company, please sign and date in the spaces indicated and return this Agreement to me.