Hande Çilingir: The Insider Founder Behind $500M Series E

Hande Çilingir, Muharrem Derinkök, Serhat Soyuerel, Arda Koterin, Mehmet Sinan Toktay and Okan Yedibela founded Insider, the ai-native omnichannel customer engagement business now serving enterprise marketing and customer-experience teams. Hande Çilingir is Co-founder and CEO; Muharrem Derinkök is Co-founder and Chief Product Officer; Serhat Soyuerel is Co-founder; Arda Koterin is Co-founder; Mehmet Sinan Toktay is Co-founder; Okan Yedibela is Co-founder.

The latest material financing milestone covered here is $500M Series E, dated 2024-11-01. The relevant total is More than $770M reported, labelled as reported cumulative funding; latest round corroborated by investor and public-agency sources. It is company-level capital or transaction value—not founder net worth.

Authentic Insider website evidence captured on 21 July 2026.

Insider founders and financing at a glance

Who is Hande Çilingir?

Hande Çilingir is Co-founder and CEO at Insider. Hande Çilingir's role should be read in its current context: founder status is permanent, while executive responsibility can change as a company scales, lists publicly or is acquired.

Founder profile: Connect with Hande Çilingir on LinkedIn.

Attributed capture of Insider's official company or leadership page, preserved as editorial identification evidence.

In the founding team, Hande Çilingir contributed to the combination of product judgment, technical execution and go-to-market work behind Insider. The public evidence does not justify claims about private ownership, personal wealth or undisclosed internal responsibilities.

Who is Muharrem Derinkök?

Muharrem Derinkök is Co-founder and Chief Product Officer at Insider. Muharrem Derinkök's role should be read in its current context: founder status is permanent, while executive responsibility can change as a company scales, lists publicly or is acquired.

Founder profile: Connect with Muharrem Derinkök on LinkedIn.

Attributed capture of Insider's official company or leadership page, preserved as editorial identification evidence.

In the founding team, Muharrem Derinkök contributed to the combination of product judgment, technical execution and go-to-market work behind Insider. The public evidence does not justify claims about private ownership, personal wealth or undisclosed internal responsibilities.

Who is Serhat Soyuerel?

Serhat Soyuerel is Co-founder at Insider. Serhat Soyuerel's role should be read in its current context: founder status is permanent, while executive responsibility can change as a company scales, lists publicly or is acquired.

Founder profile: Connect with Serhat Soyuerel on LinkedIn.

Attributed capture of Insider's official company or leadership page, preserved as editorial identification evidence.

In the founding team, Serhat Soyuerel contributed to the combination of product judgment, technical execution and go-to-market work behind Insider. The public evidence does not justify claims about private ownership, personal wealth or undisclosed internal responsibilities.

Who is Arda Koterin?

Arda Koterin is Co-founder at Insider. Arda Koterin's role should be read in its current context: founder status is permanent, while executive responsibility can change as a company scales, lists publicly or is acquired.

Founder profile: Connect with Arda Koterin on LinkedIn.

Attributed capture of Insider's official company or leadership page, preserved as editorial identification evidence.

In the founding team, Arda Koterin contributed to the combination of product judgment, technical execution and go-to-market work behind Insider. The public evidence does not justify claims about private ownership, personal wealth or undisclosed internal responsibilities.

Who is Mehmet Sinan Toktay?

Mehmet Sinan Toktay is Co-founder at Insider. Mehmet Sinan Toktay's role should be read in its current context: founder status is permanent, while executive responsibility can change as a company scales, lists publicly or is acquired.

Founder profile: Connect with Mehmet Sinan Toktay on LinkedIn.

Attributed capture of Insider's official company or leadership page, preserved as editorial identification evidence.

In the founding team, Mehmet Sinan Toktay contributed to the combination of product judgment, technical execution and go-to-market work behind Insider. The public evidence does not justify claims about private ownership, personal wealth or undisclosed internal responsibilities.

Who is Okan Yedibela?

Okan Yedibela is Co-founder at Insider. Okan Yedibela's role should be read in its current context: founder status is permanent, while executive responsibility can change as a company scales, lists publicly or is acquired.

Founder profile: Connect with Okan Yedibela on LinkedIn.

Attributed capture of Insider's official company or leadership page, preserved as editorial identification evidence.

In the founding team, Okan Yedibela contributed to the combination of product judgment, technical execution and go-to-market work behind Insider. The public evidence does not justify claims about private ownership, personal wealth or undisclosed internal responsibilities.

Why the founders built Insider

Çilingir and the founding team built Insider from Türkiye with a multi-product thesis: marketers should coordinate data, prediction, experimentation and messaging through one platform rather than assemble many disconnected point tools. The company has paired that product strategy with local teams across many markets.

This is documented company history plus editorial assessment. It does not establish private motivations beyond what the founders and company have said publicly.

What Insider does

Insider provides customer data, journey orchestration, personalization and messaging across web, app, email, SMS, WhatsApp and other channels. Sirius AI adds predictive and generative assistance, while the company describes a move toward end-to-end AI-native orchestration.

The best AI search optimization agencies comparison is useful for readers comparing the authority and visibility work that sits outside a customer-engagement platform. The guide to citation-ready content for AI search explains a related content-distribution problem.

What makes the founder thesis distinctive?

Insider’s founder-market fit is as much organizational as technical. The team scaled from an emerging technology ecosystem into a multi-continent enterprise vendor, using regional operating teams as part of its go-to-market advantage.

Our assessment is that durable differentiation must show up in customer outcomes, workflow adoption, reliable data movement and lower operating cost—not only in feature count or AI branding.

Insider financing and transaction history

The headline uses $500M Series E because it is the clearest recent milestone in the verified record. Different instruments are not silently combined: acquisition consideration, IPO proceeds, primary funding and secondary liquidity have different meanings.

What the latest milestone was intended to change

Public statements connect the milestone to some combination of product investment, AI capability, geographic expansion, hiring, acquisitions or shareholder liquidity. Those plans are attributed intentions, not proof that each outcome occurred. Evidence should include shipped capabilities, adoption, retention, unit economics and customer results after the transaction.

Founder and company timeline

The founders' public thesis

Across the available company history, the founders argue that customer data becomes valuable when operating teams can turn it into timely, coordinated action. The exact emphasis differs by company—category creation, accessibility, data ownership, real-time infrastructure or AI-assisted execution—but the test is similar: can a customer make better decisions without adding hidden complexity?

Strengths, risks and unresolved questions

Visible strengths

• A founding thesis attached to a recurring and measurable marketing workflow.
• Product history and financing evidence available from primary sources.
• A platform broad enough to influence data, orchestration and customer communication.

Material risks

• A six-founder history requires clear current-role verification rather than assuming every founder remains operational.
• Large AI-led journeys increase governance, consent and brand-safety requirements.
• The $500M round is company financing, not founder wealth or a valuation.

Questions buyers and researchers should ask

• Which founder roles are current, and which describe historical service?
• How is incremental customer or revenue impact measured against a control?
• What data, consent, model and deliverability controls constrain automated action?
• Which transaction amounts were primary capital, secondary liquidity or acquisition consideration?
• What implementation resources are required before the platform produces reliable value?

Evidence to watch over the next 12 to 18 months

Watch for independently explainable retention and expansion, transparent AI evaluation, successful migrations, product delivery tied to the announced financing purpose and current executive-role disclosures. For public companies, filings provide a stronger operating signal than promotional customer counts alone. For private companies, future financing announcements should identify transaction composition clearly.

Frequently asked questions

Who founded Insider?

Insider was founded by Hande Çilingir, Muharrem Derinkök, Serhat Soyuerel, Arda Koterin, Mehmet Sinan Toktay and Okan Yedibela.

What does Insider do?

Insider provides ai-native omnichannel customer engagement capabilities for enterprise marketing and customer-experience teams.

What is Insider's latest financing milestone?

The latest milestone verified for this profile is $500M Series E, dated 2024-11-01.

How much funding has Insider raised?

The qualified figure used here is More than $770M reported. Its status is reported cumulative funding; latest round corroborated by investor and public-agency sources; it should not be interpreted as founder wealth.

What should buyers verify?

Buyers should test data integration, consent controls, measurement, implementation effort, support, exportability and the limits placed on automated or AI-generated actions.

Tolu S.

Associate Director

Evidence-led product reviews and founder profiles for search, marketing, authority, and AI visibility teams.