David Cramer
About David Cramer
David Cramer is based in San Francisco and is best known as a co-founder of Sentry, the open-source application monitoring company. He grew up in Nebraska and taught himself to code. According to an ai.engineer speaker bio, he worked at the gaming company Curse and joined Disqus in 2008, where he built an error-logging utility that became Sentry.
His path to Sentry is documented in several interviews. Evil Martians reports that Sentry began as a side project while he worked at Disqus, and that he later worked at Dropbox. The same interview says he went full-time on Sentry in 2015. The Modern CTO podcast says he launched the hosted business behind Sentry in 2012 and describes a move from CEO to CTO. First Round Review calls him Sentry's co-founder and CPO and describes the company as worth about $3B. Sources use different titles, and Crunchbase lists him as co-founder and CTO.
His X bio describes him as a fractional executive and full-time founder at Sentry. His personal site is cra.mr and his X handle is @zeeg. He has no companies founded listed on Crunchbase, so Sentry is not counted there.
Crunchbase shows 21 investments for David Cramer, with 0 lead investments, 0 exits and 0 companies founded. Crunchbase marks the lead-investor field as empty for the deals we could see, so founders should treat him as a participating angel rather than a round lead.
PitchBook dates his recent deals mostly from mid-2025 onward. These include Comp AI (July 2025), MetalBear (September 2025), Mastra, Supermemory and Kernel (all October 2025) and Modem (February 2026). Crunchbase's investment list includes Blacksmith, MetalBear and Kernel alongside the AI names below. Neither source discloses his own check amounts.
Crunchbase counts 12 AI investments since 2023 out of his 21 total. The AI portfolio it lists includes White Circle, Mastra, Supermemory, Othello, Modem, Strix, Parse, Kernel, Comp AI, Gentrace, Pydantic Services and Leap AI.
Much of this sits close to developer tooling and AI infrastructure, which matches his day job at Sentry. At the 2025 AI Engineer conference, his bio said he was applying a practical focus to AI-assisted debugging, agent integrations and funding for software maintainers. On X he regularly posts hands-on opinions about AI models and MCP, so he follows the tooling closely.
Crunchbase lists his recent rounds as mostly Pre Seed and Seed. These include White Circle (Seed), Modem, Parse and Supermemory (Pre Seed), MetalBear and Kernel (Seed), and Comp AI (Pre Seed). It also lists Blacksmith at Series A. The sectors are AI, developer tools and infrastructure, and software. He is based in San Francisco.
We found no public statement from him on check size, fund size or a formal investment thesis, so none is given here. He has spoken publicly about founder advice. In the Evil Martians interview his contrarian view is that 20-year-olds should stop founding companies and learn from other people's mistakes first. That is one of his opinions, not a stated investing criterion.
- Supermemory: AI memory infrastructure for apps, listed by Crunchbase as a Pre Seed round, with an October 2025 date on PitchBook.
- Mastra: AI agent framework, with an October 2025 date on PitchBook.
- Kernel: Seed round on Crunchbase, with an October 2025 date on PitchBook.
- White Circle: his most recent Crunchbase investment, a Seed round.
- Modem: Pre Seed round on Crunchbase, with a February 2026 date on PitchBook.
- Comp AI: Pre Seed round on Crunchbase, with a July 2025 date on PitchBook.
- Parse: Pre Seed round on Crunchbase.
- MetalBear: developer tools company, Seed round with a September 2025 date on PitchBook.
- Blacksmith: developer infrastructure company, listed at Series A on Crunchbase.
- Othello, Strix, Gentrace, Pydantic Services, Leap AI: also in his Crunchbase AI portfolio.
- crunchbase.com/person/david-cramer
- crunchbase.com/person/25fd5df0-7cb3-03b9-71d2-cc6449e00c22
- linkedin.com/in/dmcramer
- x.com/zeeg
- ai.engineer/speakers/david-cramer
- evilmartians.com/events/podcast-david-cramer-sentry
- moderncto.io/186-david-cramer-cto-at-sentry
- review.firstround.com/sentrys-path-to-product-market-fit
AI portfolio
Investing activity
David Cramer has made 21 investments according to Crunchbase. 12 of those investments since 2023 were in AI companies, including White Circle, Mastra, Supermemory, Othello and Modem.
David Cramer appears in 2 AI deals tracked by the Lounge deals desk. The rounds are mostly Pre-seed and Seed, with a median round size of $7M. The most recent are Supermemory (Pre-seed, $3M, Jun 2026) and Strix (Seed, $6.7M, Jun 2026).
David Cramer most often invests alongside Susa Ventures, Dane Knecht, Browder Capital and Theo Browne, and the companies they back on Lounge are mostly in AI.
Deals
Frequently asked questions about David Cramer
Who is David Cramer the angel investor?
He is a San Francisco based angel investor and co-founder of Sentry, the open-source application monitoring company. Crunchbase lists 21 investments, 12 of them in AI since 2023.
What stage does David Cramer invest in?
His Crunchbase deals are mostly Pre Seed and Seed, plus one Series A (Blacksmith). He is not listed as a lead investor on any deal.
What AI startups has David Cramer backed?
Crunchbase lists White Circle, Mastra, Supermemory, Othello, Modem, Strix, Parse, Kernel, Comp AI, Gentrace, Pydantic Services and Leap AI.
What check size does David Cramer write?
His check size is not public. Third-party aggregator figures are unverified, so do not rely on them.
How can founders contact David Cramer?
He is active on X as @zeeg, and he also has a LinkedIn profile and a personal site at cra.mr. Public posts show he engages with AI and developer tooling topics.
What does David Cramer look for in startups?
He has published no formal investment criteria. His portfolio points to developer tools, AI infrastructure and software, and his experience is in building developer-facing products.
Is David Cramer an angel investor?
Yes. David Cramer invests personally as an angel. Crunchbase counts 21 investments.
What AI companies has David Cramer invested in?
David Cramer's AI investments include White Circle, Mastra, Supermemory, Othello, Modem, Strix, Parse and Kernel. The 2 rounds on Lounge are listed on this page with amounts, dates and co-investors.
Where is David Cramer based?
David Cramer is based in San Francisco, United States.
What stage does David Cramer invest at?
In the rounds tracked on Lounge, David Cramer has invested at Pre-seed and Seed, with a median round of $7M.