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Double Sharp Partners
Josh Lee's Double Sharp Partners operates a lean, engineering-focused investment firm backing developer tools and AI infrastructure from San Francisco.
Double Sharp Partners
Double Sharp Partners emerged from Lee's tenure as an early engineer and manager at Dropbox and later Benchling, where he observed that the most durable venture returns came from the picks-and-shovels layer rather than the application layer. The firm launched with a thesis that developer infrastructure, data tooling, and AI middleware would compound in value as every company became a software company. Rather than raising a traditional blind-pool fund, Lee structured the vehicle with characteristics closer to a tech-enabled single-family office, giving him permission to concentrate capital and deploy engineering talent directly into portfolio companies. The strategy spans pre-seed through Series A, with a heavy tilt toward companies building the components that other engineers rely on. Confirmed portfolio companies include Refuel, a data labeling platform for LLM training, and Anrok, a sales tax compliance engine for SaaS businesses. The firm also backs founders in cybersecurity and observability, reflecting a preference for technical moats over network effects. Deal flow originates from Lee's deep operator network, frequently resulting in allocations alongside a16z, Sequoia Capital, and Greylock on shared founder relationships. Lee runs the firm lean, with Wittenberg serving as a dedicated technical advisor to portfolio companies. The structure resembles a hybrid between a venture studio and a traditional VC, where the firm's engineering capacity acts as an accelerant for technical founders. In February 2024, Double Sharp participated in Refuel's seed extension alongside General Catalyst, reinforcing its pattern of backing infrastructure companies with repeat technical founders. The firm has not publicly disclosed total deployment or AUM. Double Sharp's structural differentiator sits in its operator-capital model: the partnership does not merely write checks but embeds engineering time into the earliest stages of company building. Lee's ability to evaluate technical founders as a peer who has managed large-scale infrastructure gives the firm outsized access to competitive rounds despite its lean presence. This collapses the traditional distance between investor and builder, making the firm function more like a founding engineer with a balance sheet than a passive LP.
General information
Firm type
Single Family Office
Year founded
—
AUM
Undisclosed
Location
Region
North America
Country
United States
City
San Francisco
Corporate office
San Francisco, CA, United States
Principals
Josh Lee
Managing Partner
Zach Wittenberg
Chief Technology Officer
Sector focus
Frequently asked questions
Who runs investment decisions at Double Sharp Partners?
Josh Lee, the Managing Partner, leads all investment decisions. Lee previously held engineering and management roles at Dropbox and Benchling, where he developed the technical network that informs the firm's deal flow. He is the central decision-maker, with CTO Zach Wittenberg providing technical evaluation on potential investments.
How does Double Sharp Partners source proprietary deal flow?
Deal flow originates almost entirely from Lee's operating background and peer engineering network. Because Lee can evaluate technical founders as a former operator who has built and scaled infrastructure teams, he gains access to rounds that generalist investors often miss. The firm frequently co-invests alongside a16z, Sequoia Capital, and Greylock on shared founder relationships rather than competing through banking-led processes.
Is Double Sharp Partners structured as a venture firm or a single-family office?
Double Sharp Partners operates as a single-family office with a venture-anchored mandate. The firm does not raise traditional blind-pool funds from external LPs, which allows Lee to concentrate capital, move quickly on terms, and deploy engineering talent into portfolio companies without standard fund-duration pressure. This structure gives the firm flexibility on check size and holding period that a conventional VC fund would not have.
What investment stages does Double Sharp Partners target?
The firm targets pre-seed through Series A, with a strong preference for being the first institutional capital into a company. Lee focuses on rounds where the founding team has a technical edge but needs early product-market-fit engineering support. The firm's capacity to embed engineering hours directly into portfolio companies makes it particularly active at the formation stage.
Which sectors does Double Sharp Partners explicitly avoid?
Double Sharp avoids consumer-facing applications, hardware-heavy companies, and sectors where distribution risk outweighs technical risk. The firm's thesis is deliberately narrow: developer infrastructure, data tooling, AI middleware, and security. Lee has publicly stated a preference for technical moats over network effects, which excludes most B2C marketplaces and media plays from the mandate.
Does Double Sharp Partners participate in fund commitments or only direct deals?
Double Sharp makes nearly all of its allocations through direct deals and co-investments alongside institutional VCs. Because Lee operates a family office structure rather than a fund-of-funds, the firm does not allocate to external GP funds as an LP. The exception would be opportunistic SPVs where the firm has a direct relationship with the founding team.
Where does the underlying wealth come from?
The firm has not publicly disclosed the source of its capital base. Lee's wealth likely stems from equity accumulated during his operating career at Dropbox and Benchling, though the firm's investment scale suggests additional undisclosed capital partners or personal liquidity events that remain private.
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