Exhibit

The purpose of the Twilio Inc. Amended and Restated 2016 Employee Stock Purchase Plan (“the Plan”) is to provide eligible employees of Twilio Inc. (the “Company”) and each Designated Company (as defined in Section 11) with opportunities to purchase shares of the Company’s Class A common stock, par value $0.001 per share (the “Common Stock”). 2,400,000 shares of Common Stock in the aggregate have been approved and reserved for this purpose, plus on January 1, 2017 and each January 1 thereafter, the number of shares reserved and available for issuance under the Plan shall be cumulatively increased by the lesser of (i) 1,800,000 shares of Common Stock, (ii) one percent of the number of shares of Class A and Class B common stock of the Company issued and outstanding on the immediately preceding December 31 or (iii) such lesser number of shares of Common Stock determined by the Administrator.

The Plan includes two components: a Code Section 423 Component (the “423 Component”) and a non-Code Section 423 Component (the “Non-423 Component”). It is intended for the 423 Component to constitute an “employee stock purchase plan” within the meaning of Section 423(b) of the U.S. Internal Revenue Code of 1986, as amended (the “Code”) and the 423 Component shall be interpreted in accordance with that intent (although the Company makes no undertaking or representation to maintain such qualification). In addition, this Plan authorizes the grant of options under the Non-423 Component that does not qualify as an “employee stock purchase plan” under Section 423 of the Code. Except as otherwise provided herein, the Non-423 Component will operate and be administered in the same manner as the 423 Component.

1.Administration. The Plan will be administered by the person or persons (the “Administrator”) appointed by the Company’s Board of Directors (the “Board”) for such purpose. The Administrator has authority at any time to: (i) adopt, alter and repeal such rules, subplans, guidelines and practices for the administration and operation of the Plan and for its own acts and proceedings as it shall deem advisable, including to accommodate the specific requirements of local laws, regulations and procedures for jurisdictions outside of the United States; (ii) interpret the terms and provisions of the Plan; (iii) make all determinations it deems advisable for the administration of the Plan; (iv) decide all disputes arising in connection with the Plan; and (v) otherwise supervise the administration of the Plan. All

interpretations and decisions of the Administrator shall be binding on all persons, including the Company and the Participants. No member of the Board or individual exercising administrative authority with respect to the Plan shall be liable for any action or determination made in good faith with respect to the Plan or any option granted hereunder.

2.Offerings. The Company will make one or more offerings to eligible employees to purchase Common Stock under the Plan (“Offerings”). Unless otherwise determined by the Administrator, the initial Offering will begin on the date of the Company’s Initial Public Offering and will end on the following May 15th (the “Initial Offering”). Thereafter, unless otherwise determined by the Administrator, an Offering will begin on the first business day occurring after each November 15th and May 15th and will end on the last business day occurring on or before the following May 15th and November 15th, respectively. The Administrator may, in its discretion, designate a different period for any Offering, provided that no Offering shall exceed 27 months in duration.

3.Eligibility. All individuals classified as employees on the payroll records of the Company and each Designated Company are eligible to participate in any one or more of the Offerings under the Plan, provided that as of the first day of the applicable Offering (the “Offering Date”) they are customarily employed by the Company or a Designated Company for more than 20 hours a week, unless the exclusion of employees who do not meet this requirement is not permissible under applicable law. Notwithstanding any other provision herein, individuals who are not contemporaneously classified as employees of the Company or a Designated Company for purposes of the Company’s or applicable Designated Company’s payroll system are not considered to be eligible employees of the Company or any Designated Company and shall not be eligible to participate in the Plan. In the event any such individuals are reclassified as employees of the Company or a Designated Company for any purpose, including, without limitation, common law or statutory employees, by any action of any third party, including, without limitation, any government agency, or as a result of any private lawsuit, action or administrative proceeding, such individuals shall, notwithstanding such reclassification, remain ineligible for participation. Notwithstanding the foregoing, the exclusive means for individuals who are not contemporaneously classified as employees of the Company or a Designated Company on the Company’s or Designated Company’s payroll system to become eligible to participate in a plan which is equivalent to this Plan is through the adoption of a subplan, which specifically renders such individuals eligible to participate therein.

(a)Participants on Effective Date. Each eligible employee at the time of the Initial Public Offering shall be deemed to be a Participant at such time. If an eligible employee is deemed to be a Participant pursuant to this Section 4(a), such individual shall be deemed not to have authorized payroll deductions or contributions and shall not purchase any Common Stock hereunder unless he or she thereafter authorizes payroll deductions or contributions by submitting (either in electronic or written form, according to procedures established by the Company) an enrollment form (in the manner described in Section 4(c)) by the end of the Initial Offering or such earlier deadline as is specified by the Administrator. If such a Participant does not authorize payroll deductions or contributions by submitting (either in electronic or written form, according to procedures established by the Company) an enrollment form by the end of the Initial Offering (or such earlier deadline, as applicable), that Participant will be deemed to have withdrawn from the Plan.

(b)Participants in Subsequent Offerings. An eligible employee who is not a Participant on any Offering Date may participate in such Offering by submitting (either in electronic or written form, according to procedures established by the Company) an enrollment form to his or her appropriate payroll location at least 15 business days before the Offering Date (or by such other deadline as shall be established by the Administrator for the Offering).

(c)Enrollment. The enrollment form will (a) state a whole percentage to be contributed from an eligible employee’s Compensation (as defined in Section 11) per pay period, (b) authorize the purchase of Common Stock in each Offering in accordance with the terms of the Plan and (c) specify the exact name or names in which shares of Common Stock purchased for such individual are to be issued or transferred pursuant to Section 10. An employee who does not enroll in accordance with these procedures will be deemed to have waived the right to participate. Unless a Participant submits (either in electronic or written form, according to procedures established by the Company) a new enrollment form or withdraws from the Plan, such Participant’s contributions and purchases will continue at the same percentage of Compensation for future Offerings, provided he or she remains eligible.

5.Employee Contributions. Each eligible employee may authorize payroll deductions at a minimum of 1 percent up to a maximum of 15 percent of such employee’s Compensation for each pay period; provided, however, that if payroll deductions are not permitted or problematic under applicable law or for administrative reasons, the Company, in its discretion, may allow eligible employees to contribute to the Plan by other means. The Company will maintain book accounts showing the amount of payroll deductions or other contributions made by each Participant for each Offering. No interest will accrue or be paid on payroll deductions or other contributions, unless required under applicable law.

6.Contribution Changes. Except in the event of a Participant increasing his or her contributions from 0 percent during the first Offering as specified in Section 4(a) or as may be determined by the Administrator in advance of an Offering, a Participant may not increase his or her contributions during any Offering and may only decrease his or her contributions once during an Offering. However, during an Offering, a Participant may increase or decrease his or her contributions with respect to the next Offering (subject to the limitations of Section 5) by submitting (either in electronic or written form, according to procedures established by the Company) a new enrollment form at least 15 business days before the next Offering Date (or by such other deadline as shall be established by the Administrator for the Offering). The Administrator may, in advance of any Offering, establish rules permitting a Participant to increase, decrease or terminate his or her contributions during an Offering.

7.Withdrawal. A Participant may withdraw from participation in the Plan by submitting a notice of withdrawal to his or her appropriate payroll location (either in electronic or written form, according to procedures established by the Company). The Participant’s withdrawal will be effective as of the next business day. Following a Participant’s withdrawal, the Company will promptly refund such individual’s entire account balance under the Plan to him or her (after payment for any Common Stock purchased before the effective date of withdrawal). Partial withdrawals are not permitted. Such an employee may not begin participation again during the remainder of the Offering, but may enroll in a subsequent Offering in accordance with Section 4.

8.Grant of Options. On each Offering Date, the Company will grant to each eligible employee who is then a Participant in the Plan an option (“Option”) to purchase on the last day of such Offering (the “Exercise Date”), at the Option Price hereinafter provided for, the lowest of (a) a number of shares of Common Stock determined by dividing such Participant’s accumulated contributions on such Exercise Date by the lower of (i) 85 percent of the Fair Market Value of the Common Stock on the Offering Date, or (ii) 85 percent of the Fair Market

Value of the Common Stock on the Exercise Date, (b) 5,000 shares; or (c) such other lesser maximum number of shares as shall have been established by the Administrator in advance of the Offering; provided, however, that such Option shall be subject to the limitations set forth below. Each Participant’s Option shall be exercisable only to the extent of such Participant’s accumulated payroll deductions and/or other contributions on the Exercise Date. The purchase price for each share purchased under each Option (the “Option Price”) will be 85 percent of the Fair Market Value of the Common Stock on the Offering Date or the Exercise Date, whichever is less.

Notwithstanding the foregoing, no Participant may be granted an Option hereunder if such Participant, immediately after the Option was granted, would be treated as owning stock possessing 5 percent or more of the total combined voting power or value of all classes of stock of the Company or any Parent or Subsidiary (as defined in Section 11). For purposes of the preceding sentence, the attribution rules of Section 424(d) of the Code shall apply in determining the stock ownership of a Participant, and all stock which the Participant has a contractual right to purchase shall be treated as stock owned by the Participant. In addition, no Participant may be granted an Option which permits his or her rights to purchase stock under the Plan, and any other employee stock purchase plan of the Company and its Parents and Subsidiaries, to accrue at a rate which exceeds $25,000 of the fair market value of such stock (determined on the Option grant date or dates) for each calendar year in which the Option is outstanding at any time. The purpose of the limitation in the preceding sentence is to comply with Section 423(b)(8) of the Code and shall be applied taking Options into account in the order in which they were granted.

9.Exercise of Option and Purchase of Shares. Each employee who continues to be a Participant in the Plan on the Exercise Date shall be deemed to have exercised his or her Option on such date and shall acquire from the Company such number of whole shares of Common Stock reserved for the purpose of the Plan as his or her accumulated contributions on such date will purchase at the Option Price, subject to any other limitations contained in the Plan; provided that, with respect to the Initial Offering, the exercise of each Option shall be conditioned on the closing of the Company’s Initial Public Offering on or before the Exercise Date. Any amount remaining in a Participant’s account at the end of an Offering solely by reason of the inability to purchase a fractional share will be carried forward to the next Offering; any other balance remaining in a Participant’s account at the end of an Offering will be refunded to the Participant promptly.

If a Participant has more than one Option outstanding under the Plan, unless he or she otherwise indicates in agreements or notices delivered hereunder: (i) each agreement or notice delivered by that Participant shall be deemed to apply to all of his or her Options under the Plan; and (ii) an Option with a lower Option Price (or an earlier granted Option, if different Options have identical Option Prices) shall be exercised to the fullest possible extent before an Option with a higher Option Price (or a later granted Option if different Options have identical Option Prices) shall be exercised.

10.Issuance of Certificates. Certificates, or book entries for uncertificated shares, representing shares of Common Stock purchased under the Plan may be issued only in the name of the employee or, if permitted by the Administrator, in the name of the employee and another person of legal age as joint tenants with rights of survivorship, or in the name of a broker authorized by the employee to be his, her or their, nominee for such purpose.

The term “Compensation” means the amount of base pay, prior to salary reduction pursuant to Sections 125, 132(f) or 401(k) of the Code or comparable reductions under laws outside the United States, and commissions, but excluding overtime, incentive or bonus awards, allowances and reimbursements for expenses such as relocation allowances or travel expenses, income or gains on the exercise, vesting or settlement of Company equity incentive awards, and similar items. The Administrator shall have the discretion to determine the application of this definition to Participants outside of the United States.

The term “Designated Company” means any present or future Affiliate or Subsidiary (as defined below) that has been designated by the Administrator to participate in the Plan. The Administrator may so designate any Affiliate or Subsidiary, or revoke any such designation, at any time and from time to time, either before or after the Plan is approved by the stockholders and may further designate such companies as participating in the 423 Component or the Non-423 Component. For purposes of the 423 Component, only Subsidiaries may be Designated Companies. The current list of Designated Companies is attached hereto as Appendix A.

The term “Fair Market Value of the Common Stock” on any given date means the fair market value of the Common Stock determined in good faith by the Administrator; provided, however, that if the Common Stock is admitted to quotation on the New York Stock Exchange (the “NYSE”) or another national securities exchange, the determination shall be made by reference to the closing price on such date. If there is no closing price for such date, the determination shall be made by reference to the last date preceding such date for which there is a closing price. Notwithstanding the foregoing, if the date for which Fair Market Value of the Common Stock is determined is the first day when trading prices for the Common Stock are reported on the NYSE or another national securities exchange, the Fair Market Value of the Common Stock shall be the “Price to the Public” (or equivalent) set forth on the cover page for the final prospectus relating to the Company’s Initial Public Offering.

12.Rights on Termination of Employment. Unless otherwise required by applicable law, if a Participant’s employment terminates for any reason before the Exercise Date for any Offering, no contributions will be taken from any pay due and owing to the Participant and the balance in the Participant’s account will be paid to such Participant or, in the case of such Participant’s death, if permitted by the Administrator, to his or her designated beneficiary as if such Participant had withdrawn from the Plan under Section 7. An employee will be deemed to have terminated employment, for this purpose, if the corporation that employs him or her, having been a Designated Company, ceases to be an Affiliate or a Subsidiary, as applicable, or if the employee is transferred to any corporation other than the Company or a Designated Company. An employee will not be deemed to have terminated employment for this purpose, if the employee is on an approved leave of absence for military service or sickness or for any other purpose

13.Special Rules. Notwithstanding anything herein to the contrary, the Administrator may adopt special rules applicable to the employees of a particular Designated Company, whenever the Administrator determines that such rules are necessary or appropriate for the implementation of the Plan in a jurisdiction where such Designated Company has employees; provided that if such rules are inconsistent with the requirements of Section 423(b) of the Code, these employees will participate in the Non-423 Component. Any special rules established pursuant to this Section 13 shall, to the extent possible, result in the employees subject to such rules having substantially the same rights as other Participants in the Plan.

17.Adjustment in Case of Changes Affecting Common Stock. In the event of a subdivision of outstanding shares of Common Stock, the payment of a dividend in Common Stock or any other change affecting the Common Stock, the number of shares approved for the Plan and the share limitation set forth in Section 8 shall be equitably or proportionately adjusted to give proper effect to such event.

19.Insufficient Shares. If the total number of shares of Common Stock that would otherwise be purchased on any Exercise Date plus the number of shares purchased under previous Offerings under the Plan exceeds the maximum number of shares issuable under the Plan, the shares then available shall be apportioned among Participants in proportion to the amount of payroll deductions accumulated on behalf of each Participant that would otherwise be used to purchase Common Stock on such Exercise Date.

21.Compliance with Law. The Company’s obligation to sell and deliver Common Stock under the Plan is subject to completion of any registration or qualification of the Common Stock under any U.S. or non-U.S. local, state or federal securities or exchange control law or under rulings or regulations of the U.S. Securities and Exchange Commission (“SEC”) or of any other governmental regulatory body, and to obtaining any approval or other clearance from any U.S. and non-U.S. local, state or federal governmental agency, which registration, qualification or approval the Company shall, in its absolute discretion, deem necessary or advisable. The Company is under no obligation to register or qualify the Common Stock with the SEC or any other U.S. or non-U.S. securities commission or to seek approval or clearance from any governmental authority for the issuance or sale of such stock.

For these purposes, “Tax Liability” shall mean any amount of U.S. or non-U.S. federal, state or local income tax, social security (or similar) contributions, payroll tax, fringe benefits tax, payment on account and/or other tax-related items related to the participation in the Plan and legally applicable to the Participant, which the Company and/or an Affiliate or Subsidiary become liable to pay on the Participant’s behalf to the relevant authorities in any jurisdiction.

25.Notification Upon Sale of Shares. Each Participant who is subject to tax in the United States with respect to his or her participation in the Plan agrees, by entering the Plan, to give the Company prompt notice of any disposition of shares purchased under the Plan where such disposition occurs within two years after the date of grant of the Option pursuant to which such shares were purchased.

26.Effective Date and Approval of Shareholders. The Plan shall take effect on the date immediately preceding the date on which the Company’s Registration Statement on Form S-1 becomes effective, subject to approval by the holders of a majority of the votes cast at a meeting of stockholders at which a quorum is present or by written consent of the stockholders.