Exhibit 99.6

March 8, 2018

MuleSoft, Inc.

77 Geary Street, Suite 400

San Francisco, California 94108

Attention: Greg Schott, Chairman and Chief Executive Officer

Re: Exclusivity

Ladies and Gentlemen:

MuleSoft, Inc. (“Company”) and salesforce.com, inc. (“Purchaser”) wish to engage in negotiations regarding a possible strategic transaction involving Purchaser and the Company (a “Possible Transaction”). In order to induce Purchaser to enter into negotiations with Company regarding a Possible Transaction (and in recognition of the time and effort that Purchaser may expend and the expenses that Purchaser may incur in pursuing these negotiations), Company, intending to be legally bound, agrees as follows:

1. The Company acknowledges and agrees that, until the earlier of the end of the Exclusivity Period (as defined in paragraph 6 below) or the date on which Purchaser advises Company in writing that Purchaser is terminating negotiations regarding a Possible Transaction, Company will not, and will not permit any of its Representatives (as defined in paragraph 6) to, directly or indirectly:

a. solicit, induce or knowingly facilitate or encourage the initiation, making, submission or announcement of any expression of interest, inquiry, proposal or offer from any person or entity (other than Purchaser and its Representatives acting on its behalf) relating to a possible Acquisition Transaction (as defined in paragraph 6);

b. participate in any discussions or negotiations with, or provide any information to, any person or entity (other than Purchaser and its Representatives acting on its behalf) relating to a possible Acquisition Transaction;

c. respond to or accept any proposal or offer from any person or entity (other than Purchaser and its Representatives acting on its behalf) relating to a possible Acquisition Transaction; or

d. approve or authorize any Acquisition Transaction or enter into any letter of intent or similar document or any agreement contemplating or otherwise relating to any Acquisition Transaction with any person or entity (other than Purchaser and its Representatives acting on its behalf).

2. The Company shall, and shall cause each of its Representatives to, immediately terminate and cease any ongoing discussions, communications or negotiations or other direct or indirect contact with any person or entity (other than Purchaser and its Representatives acting on its behalf) relating to any possible Acquisition Transaction. Company shall as promptly as practicable, and in no event more than 24 hours after receipt, provide Purchaser with written notice of any expression of interest, inquiry, proposal or offer relating to a possible Acquisition Transaction that is received by a board member or executive officer of the Company or by any of the Company’s financial or legal advisors from any person or entity (other than Purchaser or its Representatives acting on its behalf) after the date hereof and on or prior to the expiration of the Exclusivity Period (such notice to include the terms and conditions of such possible Acquisition Transaction).

3. The Company acknowledges and agrees that, in addition to all other remedies available (at law or otherwise) to Purchaser, Purchaser shall be entitled to equitable relief (including injunction and specific performance) as a remedy for any breach or threatened breach of any provision of this letter agreement. The Company further acknowledges and agrees that Purchaser shall not be required to obtain, furnish or post any bond or similar instrument in connection with or as a condition to obtaining any remedy referred to in this paragraph 3, and the Company waives any right it may have to require that Purchaser obtain, furnish or post any such bond or similar instrument.

4. Nothing in this letter agreement shall be construed as an obligation of either of the parties hereto or any of their affiliates to enter into definitive documentation regarding the Possible Transaction or to consummate the Possible Transaction or any other transaction. The existence and terms of this letter agreement shall be subject to the provisions of the Confidentiality Agreement between the Company and Purchaser, dated as of March 2, 2018.

5. This letter agreement shall be governed by and construed in accordance with the laws of the State of Delaware (without giving effect to principles of conflicts of laws). Each of the parties hereto hereby irrevocably and unconditionally submits, for itself and its property, to the exclusive jurisdiction of the Court of Chancery of the State of Delaware, or, if (and only if) such court finds it lacks jurisdiction, the Federal court of the United States of America sitting in Delaware, and any appellate court from any thereof, in any action or proceeding arising out of or relating to this letter agreement or for recognition or enforcement of any judgment relating thereto, and each of the parties hereby irrevocably and unconditionally (a) agrees not to commence any such action or proceeding except in the Court of Chancery of the State of Delaware, or, if (and only if) such court finds it lacks jurisdiction, the Federal court of the United States of America sitting in Delaware, and any appellate court from any thereof; (b) agrees that any claim in respect of any such action or proceeding may be heard and determined in the Court of Chancery of the State of Delaware, or, if (and only if) such court finds it lacks jurisdiction, the Federal court of the United States of America sitting in Delaware, and any appellate court from any thereof; (c) waives, to the fullest extent it may legally and effectively do so, any objection that it may now or hereafter have to the laying of venue of any such action or proceeding in such courts; and (d) waives, to the fullest extent

permitted by applicable law, the defense of an inconvenient forum to the maintenance of such action or proceeding in such courts. Each of the parties hereto agrees that a final judgment in any such action or proceeding shall be conclusive and may be enforced in other jurisdictions by suit on the judgment or in any other manner provided by applicable law. Each party hereto irrevocably consents to service of process inside or outside the territorial jurisdiction of the courts referred to in this paragraph 5 by U.S. mail addressed to the address of such party set forth at the beginning of this letter agreement. Nothing in this letter agreement will affect the right of any party hereto to serve process in any other manner permitted by applicable law.

6. For purposes of this letter agreement:

(a) A party’s “Representatives” shall include its officers, directors, employees, attorneys, advisors, accountants, bankers, contractors, agents, financing sources and other representatives.

(b) “Acquisition Transaction” shall mean any transaction involving:

(i) the sale, license, disposition or acquisition of all or a material portion of the business or assets of the Company and its subsidiaries (on a consolidated basis);

(ii) the issuance, grant, disposition or acquisition of (A) any material amount of capital stock or other equity securities of the Company or any “significant subsidiary” (as defined in Regulation S-X promulgated under the Securities Act) of Company (each, a “Significant Subsidiary”), (B) other than options granted to directors, officers and other employees in the ordinary course of business consistent with past practice (including with respect to timing, size, amount and terms) any option, call, warrant or right (whether or not immediately exercisable) to acquire any material amount of capital stock or other equity securities of the Company or any Significant Subsidiary of Company, or (C) any security, instrument or obligation that is or may become convertible into or exchangeable for any material amount of capital stock or other equity securities of the Company or any Significant Subsidiary of the Company (excluding, in each case, the exercise of employee stock options in the ordinary course of business); or

(iii) any merger, consolidation, business combination, share exchange, reorganization, recapitalization or similar transaction involving the Company or any Significant Subsidiary of the Company.

(c) ”Exclusivity Period” shall mean the period commencing upon execution of this letter agreement and ending at 11:59 p.m., Pacific time, on March 20, 2018, provided that the Exclusivity Period shall be extended by 24 hours if neither party provides notice of termination by 5:00 p.m., Pacific time, on the then-current expiration date.

Please confirm your agreement to the terms set forth in this letter agreement by signing below. This letter agreement may be executed in any number of counterparts (including via facsimile, .pdf or other electronic means), each of which shall be an original as regards any party whose signature appears thereon and all of which together shall constitute one and the same instrument. This letter agreement shall become binding when one or more counterparts hereof, individually or taken together, shall bear the signatures of all parties reflected hereon as signatories.

Very truly yours,

salesforce.com, inc.

By /s/ John Somorjai                                

Name: John Somorjai

Title: Executive Vice President of Corporate Development & Salesforce Ventures

Date: March 8, 2018

ACKNOWLEDGED AND AGREED:

MuleSoft, Inc.

By: /s/ Gregory Schott                                

Name: Gregory Schott

Title: Chairman & CEO

Date: March 8, 2018

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