Doug Tsui
Team Member @ Horizon Ventures
San Francisco, United States
Doug Tsui is a Series A investor at Horizon Ventures in San Francisco focused on Mobile and Security. Doug is a networking industry veteran with over 15 years of marketing and business development experience. He has broad knowledge and investment experience in the data networking, multimedia, and Internet Infrastructure area.Doug’s prior operational roles included serving as VP of Marketing for Precept Software, a network video software companywhich was acquired by Cisco Systems in 1998. He was also VP of marketing and business development for First Virtual Communications. Prior to FVC, Doug was a senior executive for four years at Cisco Systems in product marketing, business development, and major accounts. Prior to Cisco, Doug held marketing and technical management positions at 3Com/Bridge Communications and Hewlett-Packard.Doug has funded and worked with numerous high-tech startup companies as an angel investor. He has served on the Board of Directors of AudioTalk, a leading Internet voice company which was acquired by HearMe; Vertex Networks, an Ethernet switching chip company which was acquired by Mitel Corp. and was also an early investor and advisor for other networking companies such as Rapidstream, Amplify.net and Centrum Communications which was acquired by 3Com.Doug holds a B.S.E.E. degree from the University of California, Berkeley and a MBA degree from Santa Clara University. He is the past president and board member of the Asian Americans Manufacturer's Association (AAMA) and a current board member of the Hong Kong-SV.com organization.
- Total investments:
- 3
- Last investment:
- Lead investor:
- 0%
Last updated:
For AI agents: llms.txt
Industries Doug Tsui invests in
Stages Doug Tsui invests in
Countries Doug Tsui invests in
Contacts
| Type | Contact | Validation |
|---|---|---|
| Work email | ||
| Personal email | ||
| Work phone | ||
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Investment Focus
Industry
- Mobile 1 (33%)
- Security 1 (33%)
- Software 1 (33%)
- Wireless 1 (33%)
- Enterprise 1 (33%)
Stage
- Series A 1 (33%)
- Series B 1 (33%)
- Series C 1 (33%)
Investments
| Company | Description | Round | Links |
|---|---|---|---|
| Provider of 3G mobile optimization solutions. The company offers mobile broadband optimization solutions to wireless carriers and enterprises worldwide. Its carrier-grade solutions are designed to maximize network efficiency and deliver mobile user experience available for both data and multimedia applications. | $10M / Series C / Jan 24, 2005 | ||
| Identity Engines (idEngines) develops identity-based solutions for securing enterprise networks. It offers Ignition server, a network identity management device to centralize, streamline, and secure access across the network. The company also offers Ignition Portal that provides Web authentication capability to support network access control forvarious guest and visitor device types, operating systems, and browsers; Ignition Posture that provides endpoint posture checking; Ignition Guest Manager that secures network services for vendors and partners; and Ignition AutoConnect, an automated solution to streamline secure wireless and wired deployments.idEngines was acquired by Avaya Inc/Nortel Networks in December of 2008, and is now part of Extreme Networks through Extreme's acquisition of Avaya's enterprise networking business. | $13M / Series B | ||
| Identity Engines (idEngines) develops identity-based solutions for securing enterprise networks. It offers Ignition server, a network identity management device to centralize, streamline, and secure access across the network. The company also offers Ignition Portal that provides Web authentication capability to support network access control forvarious guest and visitor device types, operating systems, and browsers; Ignition Posture that provides endpoint posture checking; Ignition Guest Manager that secures network services for vendors and partners; and Ignition AutoConnect, an automated solution to streamline secure wireless and wired deployments.idEngines was acquired by Avaya Inc/Nortel Networks in December of 2008, and is now part of Extreme Networks through Extreme's acquisition of Avaya's enterprise networking business. | $8.7M / Series A |
Co-Investors
About Horizon Ventures
Horizon Ventures is a California based venture capital firm specialized in early- and late-stage investments.
Horizon Ventures Contacts
| Name | Phone | Socials | |
|---|---|---|---|
George Schneer
Venture Partner
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Art Reidel
Managing Director
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Ash Dhar
Venture Partner
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Doug Tsui
Team Member
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Jack Carsten
Managing Director
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FAQ
What does Doug Tsui invest in?
Doug Tsui invests primarily in Mobile, Security and Software startups, most often at Series A and Series B stage. Most of the 3 investments tracked by Shizune back companies in United States. The Investment Focus section breaks down every industry, stage and country in the portfolio.
How do I contact Doug Tsui?
Public channels for Doug Tsui include LinkedIn. For a verified work email and phone number, create a free Shizune account — contact data is searched across 20+ sources and validated before delivery, so your outreach lands in the right inbox.
When did Doug Tsui last invest?
The most recent investment recorded for Doug Tsui closed in Jan 2005. Shizune tracks 3 investments in total for this profile, including round sizes, stages and portfolio companies, all sourced from confirmed public funding rounds and refreshed monthly.
Is Shizune's investor data accurate?
Yes — every stat on this profile is calculated from confirmed public funding rounds monitored across hundreds of sources since 2020. This profile was last refreshed in Sep 2026 and is updated monthly. Spotted something off? Use the “Suggest an edit” link near the top of the page.
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