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Castlight HealthInvestor Overview

June 2018

NYSE: CSLT

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Safe Harbor

Statement

This presentation contains forward-looking statements regarding our trends,our strategies and the anticipated performance of our business, includingour guidance for the full year of 2018 and timing of cash flow and non-GAAPoperating break-even. These statements were made as of May 10, 2018, andreflect management’s views and expectations at that time, and are subjectto various risks, uncertainties and assumptions. If this presentation is viewedafter May 10, 2018, the information in the presentation may no longer becurrent or accurate. We disclaim any obligation to update or revise anyforward-looking statements. Undue reliance should not be placed on thesestatements.

We provide guidance in this presentation, but we will not provide any further guidance or updates on our performance during the quarter unless we do so in a public forum. Please refer to the Company’s May 10, 2018 press release and the risk factors included in the company’s filings with the Securities and Exchange Commission for discussion of important factors that may cause actual events or results to differ materially from those contained in our forward-looking statements. This presentation also includes certain non-GAAP metrics, such as non-GAAP gross profit and margin percent, non-GAAP operating expenses, non-GAAP operating loss, and non-GAAP earnings per share that we believe aid in the understanding of our financial results. A reconciliation to comparable GAAP metrics, on a historical basis, can be found in the appendix section of this presentation.

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Castlight Health

• Founded in 2008 | 500+ Employees | HQ in San Francisco

• Leading healthcare navigation SaaS platform attacking an $8B+ TAM

• Platform expanded significantly through predictive analytics

investments and the April 2017 Jiff acquisition

• Key differentiators: platform breadth; ecosystem integrations; data-

driven personalization

250+Customers

$164MARR as of 03/31/18

Break Evenin Q4 2018

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Our Journey to Health Navigation

TransparencyPredictive

AnalyticsWellbeing +

Care Guidance

Claims data-driven cost & quality tool

Data-driven personalization to drive action

One solution

addressing the

whole employee

2010-2014 2017-Today2015-2016

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Stay healthy

Access care

Manage conditions

Every Employee, Every Day

Castlight covers the full spectrum of health

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Differentiator: EcosystemConnecting all of an employer’s critical health benefits data partners

Ecosystem spans the health and

wellness spectrum

Breadth of Connectivity Depth of IntegrationsHealth claims, ecosystem partners

and user-generated data

VALUABLE

DATA ASSET

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Differentiator: Personalization

Data Recommendations

User Preferences

Claims

Employer

Data Partners

Gathers data from numerous sources in real-time

Builds personalized user profile that evolves over time

Engages each employee with personalized campaigns

Delivers campaigns through the best available channel

User Behaviors

Segmentation Engine Recommendation Engine

An intelligent personalization engine that matches employees to the right resources

Program

Behavior

Care Option

Predictive Content

Incentives

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Delivering Value in a Data-Driven Way

1.25-1.75% 2–3xDirect Cost Savings

Employee

Satisfaction

Reduction in medical costs through

steerage, as measured by Verscend*

Typical impact on

engagement of benefits

programs**

Create a delightful

benefits experience

for your employees

Program

Engagement

* Medical cost savings average for Castlight customers** Impact on engagement of third party solutions integrated with Castlight

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Target HR buyer within large, self-insured employers

Subscription model with three-year contracts

Continue to “land and expand”

Castlight’s Business Model

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Go-To-Market Strategy

Direct + Channel

Sales Strategy

Strategic

Go-to-Market

Relationship +

to Penetrate Early Majority Buyersfor Large, Innovator Buyers

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2014 2015 2016 1Q 2018

Includes Jiff’s ARR beginning April 3, 2017

$78

$110$122

$164

Strong Platform ARR Traction$

in M

illi

on

s

Platform

Transparency

Go-to-market strategy focused on platform sales to new customers and converting legacy transparency customers to the platform

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($32)

($25)

($15)-($20)

2016 2017 2018 Guidance

Non-GAAP Operating Loss

$ in M

illions

Acquisition of

Jiff completed

in 1H’17

Steady Progress Toward Break Even

Historical metrics and 2018 guidance are in accordance with ASC 606. Please see the Appendix for a discussion of the Company’s non-GAAP metrics.

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2018 Guidance

Guidance as of 05/10/18. Please see Appendix for definition of non-GAAP financial measures.

Metric Range

GAAP Revenue $150mm – $155mm

Non-GAAP Operating (Loss) ($15)mm – ($20)mm

Non-GAAP EPS ($0.11) – ($0.15)

Weighted Average Shares Outstanding 137mm – 138mm

Cash Used in Operations Mid-$20mm range

Expect to reach cash flow break-even in Q4 2018 with > $65 million of cash

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2018 Strategic Goals

GROW TH & HEALTH

SUSTA INAB IL ITY

Continue to scale platform ARR

through direct channel & Anthem

Reach cash flow & non-GAAP

operating income break even in Q4’18

I NNOVAT ION

Finish build-out of the integrated

platform to capitalize on the market

opportunity

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Thank you

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Appendix

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The Castlight Total Addressable Market

$8+ Billion

$5 Billion

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Complete Health Navigator

Castlight’s complete health experience in a single app - built just for the HR suite,

personalized for their employees.

The Castlight Health Navigation Packages

Wellbeing Navigator

Drive engagement across an

employer’s entire benefit programs

with Castlight’s personalized,

incentivized benefit navigator.

Care Guidance

Navigator

Everything employees need to make

better care decisions.

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ASC 606 Impact on Castlight

Overall, Castlight is pleased to be moving to the full retrospective adoption for ASC606. Supplemental content includes FY2016 and 2017 quarterly recast financials.

Historical Revenue Impact- Revenue impact was primarily driven by the accounting for termination provisions in

professional services revenues and variable consideration for subscription revenues, resulting in acceleration of revenue.

- Adoption of ASC 606 decreased FY’16 revenue by 3% and a increased in FY’17 revenue by less than 1%.

Historical Margin Impact- Capitalization of deferred fulfilment costs and increased capitalization of contract

acquisition costs resulted in decrease in cost of revenue and sales & marketing expense.

- Adoption of ASC 606 resulted in less than 2% gross margin change and less than 5% of

operating margin change in the restated periods.

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Non-GAAP Reconciliations – FY’17 & FY’16Reconciliation of GAAP to Non-GAAP Financial Measures

(In thousands, except per share data)

(As reported) (Adjusted for 606) (As reported) (Adjusted for 606)

Reconciliation of gross profit:

GAAP gross profit subscription $ 92,086 $ 92,958 $ 78,553 $ 75,480

Stock-based compensation 888 888 506 506

Amortization of internal-use software 968 968 976 976

Amortization of intangibles 2,253 2,253 — —

Reduction in workforce — — 5 5

Acquisition related costs 52 52 — —

Non-GAAP gross profit subscription $ 96,247 $ 97,119 $ 80,040 $ 76,967

GAAP gross margin subscription 76.4 % 76.6 % 82.7 % 82.1 %

Non-GAAP gross margin subscription 79.9 % 80.0 % 84.2 % 83.7 %

GAAP gross loss professional services and other $ (7,841) $ (7,590) $ (11,414) $ (8,638)

Stock-based compensation 1,656 1,080 1,961 1,204

Reduction in workforce — — 103 103

Acquisition related costs 160 160 — —

Non-GAAP gross loss professional services $ (6,025) $ (6,350) $ (9,350) $ (7,331)

GAAP gross margin professional services and other (71.7)% (71.3)% (171)% (128)%

Non-GAAP gross margin professional services and other (55.1)% (59.6)% (140)% (108)%

GAAP gross profit $ 84,245 $ 85,368 $ 67,139 $ 66,842

Impact of non-GAAP adjustments 5,977 5,401 3,551 2,794

Non-GAAP gross profit $ 90,222 $ 90,769 $ 70,690 $ 69,636

GAAP gross margin 64.1 % 64.7 % 66.0 % 67.7 %

Non-GAAP gross margin 68.6 % 68.8 % 69.5 % 70.5 %

Reconciliation of operating expenses:

GAAP sales and marketing $ 62,313 $ 59,767 $ 58,800 $ 58,641

Stock-based compensation (9,665) (9,665) (8,843) (8,843)

Amortization of intangibles (1,344) (1,344) — —

Reduction in workforce — — (422) (422)

Acquisition related costs (909) (909) — —

Non-GAAP sales and marketing $ 50,395 $ 47,849 $ 49,535 $ 49,376

GAAP research and development $ 54,502 $ 54,502 $ 40,460 $ 40,460

Stock-based compensation (7,415) (7,415) (5,959) (5,959)

Reduction in workforce — — (136) (136)

Acquisition related costs (393) (393) — —

Non-GAAP research and development $ 46,694 $ 46,694 $ 34,365 $ 34,365

GAAP general and administrative $ 28,825 $ 28,825 $ 26,859 $ 26,859

Stock-based compensation (4,954) (4,954) (4,743) (4,743)

Litigation settlement (250) (250) (2,876) (2,876)

Amortization of intangibles (50) (50) — —

Change in fair value of contingent consideration liability 671 671 — —

Reduction in workforce — — (90) (90)

Acquisition related costs (3,423) (3,423) (1,731) (1,731)

Non-GAAP general and administrative $ 20,819 $ 20,819 $ 17,419 $ 17,419

Year Ended December 31, 2017 Year Ended December 31, 2016

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Non-GAAP Reconciliations – FY’17 & FY’16 (cont.)

Reconciliation of GAAP to Non-GAAP Financial Measures

(In thousands, except per share data)

(As reported) (Adjusted for 606) (As reported) (Adjusted for 606)

Year Ended December 31, 2017 Year Ended December 31, 2016

GAAP operating expense $ 145,640 $ 143,094 $ 126,119 $ 125,960

Impact of non-GAAP adjustments (27,732) (27,732) (24,800) (24,800)

Non-GAAP operating expense $ 117,908 $ 115,362 $ 101,319 $ 101,160

Reconciliation of operating loss:

GAAP operating loss $ (61,395) $ (57,726) $ (58,980) $ (59,118)

Impact of non-GAAP adjustments 33,709 33,133 28,351 27,594

Non-GAAP operating loss $ (27,686) $ (24,593) $ (30,629) $ (31,524)

Reconciliation of other income, net:

GAAP other income, net $ 618 $ 618 $ 432 $ 432

Gain on sale of investment in related party (1,375) (1,375) — —

Expense related to expiration of SAP warrant 1,132 1,132 — —

Non-GAAP other income, net $ 375 $ 375 $ 432 $ 432

Net loss and net loss per share:

GAAP net loss $ (55,571) $ (51,902) $ (58,548) $ (58,686)

Total pre-tax impact of non-GAAP adjustments 33,466 32,890 28,351 27,594

Release of deferred tax valuation allowance due to business

combination (5,206) (5,206) — —

Non-GAAP net loss $ (27,311) $ (24,218) $ (30,197) $ (31,092)

GAAP net loss per share, basic and diluted $ (0.44) $ (0.41) $ (0.58) $ (0.58)

Non-GAAP net loss per share, basic and diluted $ (0.22) $ (0.19) $ (0.30) $ (0.31)

Shares used in basic and diluted net loss per share computation 125,534 125,534 100,798 100,798

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Non-GAAP Financial MeasuresTo supplement Castlight Health’s financial statements presented in accordance with generally accepted accountingprinciples (GAAP), we also use and provide investors and others with non-GAAP measures of certain components offinancial performance, including non-GAAP gross profit and margin, non-GAAP operating expense, non-GAAPoperating loss, non-GAAP other income, net, non-GAAP net loss and non-GAAP net loss per share. Non-GAAP grossprofit and margin, non-GAAP operating expense, non-GAAP operating loss, non-GAAP other income, net and non-GAAP net loss exclude stock-based compensation, litigation settlement, amortization of intangibles, capitalizationand amortization of internal-use software, loss on sublease, gain on sale of investment in related party, expenserelated to expiration of SAP warrant, changes in fair value of contingent consideration liability, and charges relatedto the acquisition of Jiff and the associated tax impact of these items, where applicable.

We believe that these non-GAAP financial measures provide useful supplemental information to investors andothers, facilitate the analysis of the company’s core operating results and comparison of operating results acrossreporting periods, and can help enhance overall understanding of the company’s historical financial performance.

We have provided a reconciliation of each non-GAAP financial measure to the most directly comparable GAAPfinancial measure, except that we have not reconciled our non-GAAP operating loss and net loss per share guidancefor the full year 2018 to comparable GAAP operating loss and net loss per share guidance because we do not provideguidance for stock-based compensation expense, and capitalization and amortization of internal-use software,which are reconciling items between GAAP and non-GAAP operating loss. The factors that may impact our futurestock-based compensation expense, and capitalization and amortization of internal-use software are out of ourcontrol and/or cannot be reasonably predicted, and therefore we are unable to provide such guidance withoutunreasonable effort. Factors include our market capitalization and related volatility of our stock price and ourinability to project the cost or scope of internally produced software.

These non-GAAP financial measures should be considered in addition to, not as a substitute for or in isolation from,measures prepared in accordance with GAAP. Further, these non-GAAP measures may differ from the non-GAAPinformation used by other companies, including peer companies, and therefore comparability may be limited.Castlight Health encourages investors and others to review the company’s financial information in its entirety andnot rely on a single financial measure.