Sebastian Wallin Net Worth (Estimated)

Who is Sebastian Wallin?

Sebastian Wallin is a founder associated with Castle in Y Combinator's Winter 2016 batch.

About Castle

Instantly stop automated and human-originated account takeovers, fake accounts, and any behavior that violates your platform policies.

Model inputs

• Stage: series-a
• Valuation tier: raise-10x
• Funding input: reported raise $9.2M
• Valuation note: Replace leftover $2M 2016 seed. Lock last published priced primary $9.2M Series A. Do not lock lifetime $11.6–11.7M or a Castle name-collision raise.
• Research as-of: 2026-09-14
• Funding source: https://blog.castle.io/weve-raised-9-2-million-led-by-index-ventures/

FAQ: Sebastian Wallin net worth and Castle valuation

What is Sebastian Wallin's net worth?

Sebastian Wallin's estimated net worth / paper wealth is $9.0M (range $6.3M–$13.5M) as of 2026. Entrepreneurial Check publishes an independent model-based estimate from public company and role data.

Sebastian Wallin net worth

Sebastian Wallin's estimated net worth / paper wealth is $9.0M (range $6.3M–$13.5M) as of 2026. This Sebastian Wallin net worth figure is estimated paper wealth, not a verified statement of assets.

How much is Sebastian Wallin worth?

Sebastian Wallin's estimated net worth / paper wealth is $9.0M (range $6.3M–$13.5M) as of 2026. How much Sebastian Wallin is worth here means estimated paper wealth from public company and role data — not financial advice.

How rich is Sebastian Wallin?

Sebastian Wallin's estimated net worth / paper wealth is $9.0M (range $6.3M–$13.5M) as of 2026. “How rich is Sebastian Wallin” here means estimated paper wealth from public company and role data — not verified net worth or financial advice.

Sebastian Wallin fortune

Sebastian Wallin's estimated net worth / paper wealth is $9.0M (range $6.3M–$13.5M) as of 2026. This Sebastian Wallin fortune figure is estimated paper wealth only, not a verified statement of assets.

Sebastian Wallin equity value

Sebastian Wallin's estimated net worth / paper wealth is $9.0M (range $6.3M–$13.5M) as of 2026. Sebastian Wallin equity value on this page is modeled paper wealth from estimated ownership — not a disclosed cap table or verified net worth.

What is Castle valuation?

Castle's estimated valuation on Entrepreneurial Check is $92.0M. Independent model output, not a verified appraisal or official mark.

What is Castle post-money valuation?

Castle's estimated valuation on Entrepreneurial Check is $92.0M. That figure is a modeled post-money mark when a public raise is available — not a verified appraisal or official mark.

What is Castle funding?

Castle funding, when a public raise is available, is a model input on this Entrepreneurial Check profile. How much Castle raised is not a complete cap table — figures are estimates only.

How much did Castle raise?

How much Castle raised, when disclosed, informs the estimated Castle valuation and founder paper-wealth figures on this page. Independent estimate only — not a complete cap table or financial advice.

How much money did Castle raise?

How much money Castle raised, when a public figure is available, is a model input for the estimated Castle valuation on this profile. Estimates only — not a complete cap table.

What is Castle series funding?

Castle series funding, when a public raise is disclosed, informs the estimated Castle valuation here. Not a complete financing history.

What company is Sebastian Wallin building?

Sebastian Wallin is CTO at Castle, a Y Combinator-backed startup (batch W16).

What does Castle do?

Castle — Block bots & bad behavior

What YC batch is Sebastian Wallin from?

Sebastian Wallin is associated with Y Combinator batch W16.

Where is Sebastian Wallin based?

Public directory data lists Sebastian Wallin's region as Sweden.

What industry is Sebastian Wallin in?

Sebastian Wallin is listed under B2B, Security.

How big is Castle?

Public data lists Castle's team size as 20.

Is Entrepreneurial Check affiliated with Y Combinator?

No. Entrepreneurial Check is an independent informational site and is not affiliated with, endorsed by, or sponsored by Y Combinator or the profiled companies.