2017 Equity Incentive Plan CSOP Sub-Plan for UK Eligible Employees, with Forms of CSOP Stock Option Grant Notice and CSOP Option Agreement thereunder

This sub-plan to the Appian Corporation 2017 Equity Incentive Plan (“the Plan”) is intended to take effect as a Schedule 4 Company Share Option Plan (“the CSOP Sub-Plan”).

Appian Corporation (“the Company”) has established the CSOP Sub-Plan under Rule 2(b)(x) of the Plan, which authorises the Board to adopt sub-plans to the Plan.

The purpose of the CSOP Sub-Plan is to enable the grant to, and subsequent exercise by, employees and directors in the United Kingdom, on a tax favoured basis, of options to acquire shares in the Company under the Plan.

The CSOP Sub-Plan is intended to comply with Schedule 4 to ITEPA 2003.

The rules of the Plan, in their present form and as amended from time to time, shall, with the modifications set out in this sub-plan, form the rules of the CSOP Sub-Plan. In the event of any conflict between the rules of the Plan and this sub-plan, the sub-plan shall prevail.

The CSOP Sub-Plan shall form part of the Plan and not a separate and independent plan.

In the CSOP Sub-Plan, unless the context otherwise requires, the following words and expressions have the following meanings:

In this supplement, unless the context otherwise requires:

The companies participating in the CSOP Sub-Plan shall be each a Constituent Company.

The Shares shall form part of the ordinary share capital of the Company which satisfy the conditions specified in paragraphs 16-20 inclusive of Schedule 4.

An option granted under the CSOP Sub-Plan shall be granted under and subject to the rules of the Plan as modified by this sub-plan.

An Option Agreement issued in respect of an Option shall expressly state that it is issued in respect of an Option. An option which is not so identified shall not constitute an Option.

An Option Agreement issued in respect of an Option shall specify:

An Option may not be granted earlier than the Adoption Date.

An Option may not be granted to an individual who is not an Eligible Employee at the Date of Grant.

For the avoidance of doubt and notwithstanding Section 1(b) of the Plan, an Option may not be granted under the CSOP Sub-Plan to a Consultant or Non-Employee Director.

If an Eligible Employee’s status changes to that of Consultant or Non-Employee Director, this shall be regarded as a termination of employment for the purposes of the CSOP Sub-Plan.

An Option shall be personal to the Eligible Employee to whom it is granted and, subject to rule 25, shall not be capable of being transferred, charged or otherwise alienated and shall lapse immediately if the Participant purports to transfer, charge or otherwise alienate the Option.

Section 5(e) of the Plan shall be construed accordingly.

For the avoidance of doubt, Shares placed under Option under the CSOP Sub-Plan shall be taken into account for the purpose of Rule 3 of the Plan.

to exceed £250,000 (or any other amount specified in section 536(1)(e) of ITEPA 2003 at the relevant time), the whole of that Excess Option shall take effect as a share option granted outside the Plan) but subject to the same terms and conditions as if it were an Option) and without the tax advantages available for Options.

Notwithstanding Rule 5(b) of the Plan, the amount payable per Share on the exercise of an Option shall not be less than the Market Value (as defined in the CSOP Sub-Plan) of a Share on the Date of Grant and shall be stated on the Date of Grant.

will be a “Good Leaver” and may exercise their Option as provided in the Option Agreement during the period of six months following the date the Option Holder ceased to be an Employee and the Option shall lapse at the end of the exercise period to the extent it is not exercised.

The period during which an Option shall remain exercisable shall be stated in the Option Agreement and any Option not exercised by that time shall lapse immediately.

A Participant's employer or former employer may decide to release the Participant from, or not to enforce, any part of the Participant's obligations in respect of Employer NICs under rule 22.1 and rule 22.2.

The amount due on the exercise of an Option shall be paid in cash or by cheque or banker’s draft and may be paid out of funds provided to the Participant on loan by a bank, broker or other person. Notwithstanding Sections 5(c)(ii), (iii), (iv) or (v) of the Plan, the amount may not be paid by the transfer to the Company of Shares or by a “net exercise”

Subject only to compliance by the Participant with the rules of the CSOP Sub-Plan and to any delay necessary to complete or obtain:

the Company shall, as soon as reasonably practicable and in any event not later than thirty days after the date of exercise of an Option, issue or transfer to the Participant, or procure the issue or transfer to the Participant of, the number of Shares specified in the notice of exercise and shall deliver to the Participant, or procure the delivery to the Participant of, a share certificate in respect of such Shares together with, in the case of the partial exercise of an Option, an Option Agreement in respect of, or the original Option Agreement endorsed to show, the unexercised part of the Option.

If a Participant dies, his personal representatives shall be entitled to exercise his Options for the twelve month period following his death. If not so exercised, the Options shall lapse immediately.

If a company (“Acquiring Company”) obtains Control of the Company as a result of:

a Participant may, at any time during the period set out in rule 26.2, by agreement with the Acquiring Company, release his Option in whole or in part in consideration of the grant to him of a new option (“New Option”) which is equivalent to the Option but which relates to shares in the Acquiring Company (or some other company falling within paragraph 27(2) (b) of Schedule 4) (“New Shares”).

The period referred to in rule 26.1 is the period of six months beginning with the time when the person making the offer has obtained Control of the Company and any condition subject to which the offer is made has been satisfied or such other period as is specified in Schedule 4.

The New Option shall not be regarded for the purpose of this rule 26 as equivalent to the Option unless:

The date of grant of the New Option shall be deemed to be the same as the Date of Grant of the Option.

In the application of the CSOP Sub-Plan to the New Option, where appropriate, references to “Company” and “Shares” shall be read as if they were references to the company to whose shares the New Option relates and the New Shares, respectively.

All Shares issued on the exercise of an Option shall, as to any voting, dividend, transfer and other rights, including those arising on a liquidation of the Company, rank equally in all respects and as one class with the Shares in issue at the date of such exercise save as regards any rights attaching to such Shares by reference to a record date prior to the date of such exercise.

Notwithstanding Rule 2(b)(vi) of the Plan, no amendment to a Key Feature of the CSOP Sub‑Plan shall take effect if, as a result of the amendment, the CSOP Sub-Plan would no longer be a Schedule 4 CSOP.

In exercising any discretion which it may have under the CSOP Sub-Plan, the Board shall act fairly and reasonably.

The provisions of the Plan dealing with:

shall not form part of, and shall be disregarded for the purposes of the CSOP Sub-Plan.

Additional Terms/Acknowledgements: Optionholder acknowledges receipt of, and understands and agrees to, this Stock Option Grant Notice, the Option Agreement, the CSOP Sub-Plan and the Plan. Optionholder acknowledges and agrees that this Stock Option Grant Notice and the Option Agreement may not be modified, amended or revised except as provided in the CSOP Sub-Plan. Optionholder further acknowledges that as of the Date of Grant, this Stock Option Grant Notice, the Option Agreement, the CSOP Sub-Plan and the Plan set forth the entire understanding between Optionholder and the Company regarding this option award and supersede all prior oral and written agreements, promises and/or representations on that subject with the exception of, if applicable, (i) equity awards previously granted and delivered to Optionholder, (ii) any compensation recovery policy that is adopted by the Company or is otherwise required by applicable law and (iii) any written employment agreement, severance agreement, offer letter or other written agreement entered into between the Company and Participant specifying the terms that should govern this specific option. By accepting this option, Optionholder consents to receive such documents by electronic delivery and to participate in the Plan through an on-line or electronic system established and maintained by the Company or another third party designated by the Company.

Pursuant to your Stock Option Grant Notice (“Grant Notice”) and this Option Agreement, Appian Corporation (the “Company”) has granted you an option under the CSOP Sub-Plan to its 2017 Equity Incentive Plan (together the “Plan”) to purchase the number of shares of the Company’s Common Stock indicated in your Grant Notice at the exercise price indicated in your Grant Notice. The option is granted to you effective as of the date of grant set forth in the Grant Notice (the “Date of Grant”). If there is any conflict between the terms in this Option Agreement, the CSOP Sub-Plan and the Plan, the terms of the CSOP Sub-Plan will control. Capitalized terms not explicitly defined in this Option Agreement or in the Grant Notice but defined in the Plan or the CSOP Sub-Plan will have the same definitions as in the Plan or the CSOP Sub-Plan.

2.NUMBER OF SHARES AND EXERCISE PRICE. The number of shares of Common Stock subject to your option and your exercise price per share in your Grant Notice will be adjusted for Capitalization Adjustments as provided in the CSOP Sub-Plan.

3.CSOP. Your option is subject to the provisions of the CSOP Sub-Plan and to Schedule 4 to the Income Tax (Earnings and Pensions) Act 2003. This statement shall take precedent over any conflicting statement about the terms of your option.

4.METHOD OF PAYMENT. You must pay the full amount of the exercise price for the shares you wish to exercise. You may pay the exercise price in cash or by check, bank draft or money order payable to the Company provided that at the time of exercise the Common Stock is publicly traded, pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company or the receipt of irrevocable instructions to pay the aggregate exercise price to the Company from the sales proceeds. This manner of payment is also known as a “broker-assisted exercise”, “same day sale”, or “sell to cover”.

7.TERM. You may not exercise your option before the Date of Grant or after the expiration of the option’s term. The term of your option expires, subject to the provisions of Section 5(h) of the Plan, upon the earliest of the following:

(b)ninety (90) days after the termination of your Continuous Service for any reason other than Cause, your leaving as a Good Leaver or your death; provided, however, that if during any part of such ninety (90) day period your option is not exercisable solely because of the condition set forth in the section above regarding “Securities Law Compliance,” your option will not expire until the earlier of the Expiration Date or until it has been exercisable for an aggregate period of ninety (90) days after the termination of your Continuous Service; provided further, if during any part of such ninety (90) day period, the sale of any Common Stock received upon exercise of your option would violate the Company’s insider trading policy, then your option will not expire until the earlier of the Expiration Date or until it has been exercisable for an aggregate period of ninety (90) days after the termination of your Continuous Service during which the sale of the Common Stock received upon exercise of your option would not be in violation of the Company’s insider trading policy;

your option if your Grant Notice so permits) during its term by (i) delivering a Notice of Exercise (in a form designated by the Company) or completing such other documents and/or procedures designated by the Company for exercise and (ii) paying the exercise price and any applicable withholding taxes to the Company’s Secretary, stock plan administrator, or such other person as the Company may designate, together with such additional documents as the Company may then require.

(b)By exercising your option you agree that, as a condition to any exercise of your option, the Company may require you to enter into an arrangement providing for the payment by you to the Company of any tax and National Insurance Contribution withholding obligation of the Company arising by reason of (i) the exercise of your option, (ii) the lapse of any substantial risk of forfeiture to which the shares of Common Stock are subject at the time of exercise, or (iii) the disposition of shares of Common Stock acquired upon such exercise.

(a)Your option is not an employment or service contract, and nothing in your option will be deemed to create in any way whatsoever any obligation on your part to continue in the employ of the Company or an Affiliate, or of the Company or an Affiliate to continue your employment. In addition, nothing in your option will obligate the Company or an Affiliate, their respective stockholders, boards of directors, officers or employees to continue any relationship that you might have as a Director or Consultant for the Company or an Affiliate.

(b)In accepting your option, you acknowledge, understand and agree that:

(i)the Plan is established voluntarily by the Company, it is discretionary in nature, and may be amended, suspended or terminated by the Company at any time, to the extent permitted under the Plan;

(ii)the grant of your option is voluntary and occasional and does not create any contractual or other right to receive future grants of options (whether on the same or different terms), or benefits in lieu of options, even if options have been granted in the past;

(iii)your option and any shares of Common Stock acquired under the Plan, and the income and value of same, are not part of normal or expected compensation for any purpose, including, without limitation, calculating any severance, resignation, termination, redundancy, dismissal, end-of-service payments, bonuses, long-service awards, pension or retirement or welfare benefits or similar payments;

(iv)the future value of the shares of Common Stock underlying the option is unknown, indeterminable, and cannot be predicted with certainty;

(v)neither the Company nor any Affiliate shall be liable for any foreign exchange rate fluctuation between your local currency and the United States Dollar that may affect the value of your option or of any amounts due to you pursuant to the exercise of your option or the subsequent sale of any shares of Common Stock acquired upon exercise;

(vi)no claim or entitlement to compensation or damages shall arise from forfeiture of this option resulting from the termination of your Continuous Service (for any reason whatsoever, whether or not later found to be invalid or in breach of employment laws in the jurisdiction where you are employed or the terms of your employment or service agreement, if any), and in consideration of the grant of this option to which you are otherwise not entitled, you irrevocably agree never to institute any claim against the Company or any Affiliate, waive your ability, if any, to bring any such claim, and release the Company and any Affiliate from any such claim; if, notwithstanding the foregoing, any such claim is allowed by a court of competent jurisdiction, then, by participating in the Plan, you shall be deemed irrevocably to have agreed not to pursue such claim and agree to execute any and all documents necessary to request dismissal or withdrawal of such claim.

(a)At the time you exercise your option, in whole or in part, and at any time thereafter as requested by the Company, you hereby authorize the Company and any Affiliate to make any withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for (including by means of a “same day sale” pursuant to a program developed under

Regulation T as promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations of the Company or an Affiliate, if any, which arise in connection with the exercise of your option.

(b)Depending on the circumstances, on exercise of your option you may have an income tax liability under PAYE and may be required to pay national insurance contributions (NICs). If so, then:

(1)the Company or the company which employs you may require you to pay amounts in respect of PAYE and NICs liability in cash, including all of his employer’s secondary class 1 NICs liability, arising from exercise of your option; and

(2)in some circumstances the Company may withhold the number of shares of Common Stock required to meet the liabilities in respect of PAYE, primary (employee) class 1 NICs and secondary (employer) class 1 NICs.

(c)Your option may only be exercised if you confirm (in writing) that you agree to the requirements of the CSOP Sub-Plan relating to PAYE and NICs (Rule 22). This may be done at the time of exercise.

(d)You may not exercise your option unless the tax withholding obligations of the Company and/or any Affiliate are satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company will have no obligation to issue a certificate for such shares of Common Stock or release such shares of Common Stock from any escrow provided for herein, if applicable, unless such obligations are satisfied.

12.TAX CONSEQUENCES. You hereby agree that the Company does not have a duty to design or administer the Plan or its other compensation programs in a manner that minimizes your tax liabilities. You will not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from your option or your other compensation.

13.NOTICES. Any notices provided for in your option or the Plan will be given in writing (including electronically) and will be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five (5) days after deposit in the United States mail, postage prepaid, addressed to you at the last address you provided to the Company. The Company may, in its sole discretion, decide to deliver any documents related to participation in the Plan and this option by electronic means or to request your consent to participate in the Plan by electronic means. By accepting this option, you consent to receive such documents by electronic delivery and to participate in the Plan through an on-line or electronic system established and maintained by the Company or another third party designated by the Company.

14.GOVERNING PLAN DOCUMENT. Your option is subject to all the provisions of the Plan, the provisions of which are hereby made a part of your option, and is further subject to all interpretations, amendments, rules and regulations, which may from time to time be promulgated and adopted pursuant to the Plan. If there is any conflict between the provisions of your option and those of the Plan, the provisions of the Plan will control. In addition, your option (and any compensation paid or shares issued under your option) is subject to recoupment in accordance with The Dodd–Frank Wall Street Reform and Consumer Protection Act and any implementing regulations thereunder, any clawback policy adopted by the Company and any compensation recovery policy otherwise required by applicable law.

15.OTHER DOCUMENTS. You hereby acknowledge receipt of and the right to receive a document providing the information required by Rule 428(b)(1) promulgated under the Securities Act, which includes the Plan prospectus. In addition, you acknowledge receipt of the Company’s policy permitting certain individuals to sell shares only during certain “window” periods and the Company’s insider trading policy, in effect from time to time.

16.EFFECT ON OTHER EMPLOYEE BENEFIT PLANS. The value of this option will not be included as compensation, earnings, salaries, or other similar terms used when calculating your benefits under any employee benefit plan sponsored by the Company or any Affiliate, except as such plan otherwise expressly provides. The Company expressly reserves its rights to amend, modify, or terminate any of the Company’s or any Affiliate’s employee benefit plans.

17.VOTING RIGHTS. You will not have voting or any other rights as a stockholder of the Company with respect to the shares to be issued pursuant to this option until such shares are issued to you. Upon such issuance, you will obtain full voting and other rights as a stockholder of the Company. Nothing contained in this option, and no action taken pursuant to its provisions, will create or be construed to create a trust of any kind or a fiduciary relationship between you and the Company or any other person.

18.SEVERABILITY. If all or any part of this Option Agreement or the Plan is declared by any court or governmental authority to be unlawful or invalid, such unlawfulness or invalidity will not invalidate any portion of this Option Agreement or the Plan not declared to be unlawful or invalid. Any Section of this Option Agreement (or part of such a Section) so declared to be unlawful or invalid shall, if possible, be construed in a manner which will give effect to the terms of such Section or part of a Section to the fullest extent possible while remaining lawful and valid.

(a)The rights and obligations of the Company under your option will be transferable to any one or more persons or entities, and all covenants and agreements hereunder will inure to the benefit of, and be enforceable by the Company’s successors and assigns.

(b)You agree upon request to execute any further documents or instruments necessary or desirable in the sole determination of the Company to carry out the purposes or intent of your option.

(c)You acknowledge and agree that you have reviewed your option in its entirety, have had an opportunity to obtain the advice of counsel prior to executing and accepting your option, and fully understand all provisions of your option.

(d)This Option Agreement will be subject to all applicable laws, rules, and regulations, and to such approvals by any governmental agencies or national securities exchanges as may be required.

(e)All obligations of the Company under the Plan and this Option Agreement will be binding on any successor to the Company, whether the existence of such successor is the result of a direct or indirect purchase, merger, consolidation, or otherwise, of all or substantially all of the business and/or assets of the Company.

20.DATA TRANSFER. You explicitly and unambiguously consent to the collection, use and transfer, in electronic or other form, of your personal data as described in this document by and among, as applicable, your employer, the Company and its Affiliates for the exclusive purpose of implementing, administering and managing your participation in the Plan. You understand that the Company, its Affiliates and your employer hold certain personal information about you, including, but not limited to, name, home address and telephone number, date of birth, social security number (or other identification number), salary, nationality, job title, any shares of stock or directorships held in the Company, details of all options or any other entitlement to shares of stock awarded, canceled, purchased, exercised, vested, unvested or outstanding in your favor for the purpose of implementing, managing and administering the Plan (“Data”). You understand that the Data may be transferred to any third parties assisting in the implementation, administration and management of the Plan, that these recipients may be located in your country or elsewhere, in particular in the US, and that the recipient country may have different data privacy laws providing less protections of your personal data than your country. You may request a list with the names and addresses of any potential recipients of the Data by contacting Chris Winters as the stock plan administrator at the Company (the “Stock Plan Administrator”). You authorize the recipients to receive, possess, process, use, retain and transfer the Data, in electronic or other form, for the purposes of implementing, administering and managing your participation in the Plan, including any requisite transfer of such Data, as may be required to a broker or other third party with whom you may elect to deposit any shares of Common Stock acquired upon the exercise of your option. You understand that Data will be held only as long as is necessary to implement, administer and manage your participation in the Plan. You may, at any time, view the Data, request additional information about the storage and processing of the Data, require any necessary amendments to the Data or refuse or withdraw the consents herein, in any case without cost, by contacting the Stock Plan Administrator in writing. You understand that refusing or withdrawing consent may affect your ability to participate in the Plan. For more information on the consequences of refusing to consent or withdrawing consent, you may contact the Stock Plan Administrator.

21.INSIDER TRADING/MARKET ABUSE. You acknowledge that, depending on your country, you may be subject to insider trading restrictions and/or market abuse laws, which may affect your ability to acquire or sell the shares of Common Stock or rights to the shares of Common Stock under the Plan during such times as you are considered to have “inside information” regarding the Company (as defined by the laws in your country). Any restrictions under these laws or regulations are separate from and in addition to any restrictions that may be imposed under any applicable Company insider trading policy. You acknowledge that it is your responsibility to comply with any applicable restrictions, and you are advised to speak to your personal advisor on this matter.

22.GOVERNING LAW/VENUE. This Option Agreement is governed by the laws of the State of Delaware without resort to that state’s conflicts of laws rules. For purposes of any action, lawsuit or other proceedings brought to enforce this Option Agreement, relating to it, or arising from it, the parties hereby submit to and consent to the sole and exclusive jurisdiction of the courts within Fairfax County, Virginia, and no other courts, where this grant is made and/or to be performed.

This constitutes notice to Appian Corporation (the “Company”) under my stock option that I elect to purchase the below number of shares of Common Stock of the Company (the “Shares”) for the price set forth below.

By this exercise, I agree (i) to provide such additional documents as you may require pursuant to the terms of the Appian Corporation 2017 Equity Incentive Plan and CSOP Sub-Plan, (ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this option, and (iii) to make adequate provision to cover the tax liabilities, if any, including employer National Insurance Contributions, which arise in connection with the option.