# Alexander Ratner

> Alexander Ratner is a seed investor backing Artificial Intelligence. See 2 investments, round sizes, portfolio and contact details. Updated Oct 2026.

- Type: Angel Investor
- Location: Stanford, United States
- Total investments: 2
- Last investment: Dec 2022
- Lead investor: 0%
- Last updated: Oct 2026
- LinkedIn: https://www.linkedin.com/in/alexander-ratner-038ba239

Alexander Ratner is a seed investor in Stanford focused on Artificial Intelligence and Database. Alex Ratner is a third-year PhD student at the Stanford InfoLab working under Chris Re. Alex works on new machine learning paradigms for settings where limited or no hand-labeled training data is available, motivated in particular by information extraction problems in domains like genomics, clinical diagnostics, and political science. He coleadsthe development of the Snorkel framework for lightweight information extraction.

## Contacts

5 contacts available for Alexander Ratner: work email, personal email, work phone, personal phone and socials. Sign up free to unlock them: https://app.shizune.co/sign-up/investor-profiles/find-email/alexander-ratner?utm_source=investor_profile

## Investment focus

### Industry

| Industry | Investments | Share |
| --- | --- | --- |
| Artificial Intelligence | 2 | 100% |
| Database | 1 | 50% |
| Open Source | 1 | 50% |
| Generative AI | 1 | 50% |
| Search Engine | 1 | 50% |

8 industries tracked in total.

### Stage

| Stage | Investments | Share |
| --- | --- | --- |
| Seed | 1 | 50% |
| Series A | 1 | 50% |

### Country

| Country | Investments | Share |
| --- | --- | --- |
| Germany | 1 | 50% |
| United States | 1 | 50% |

## Investments

| Company | Description | Round size | Stage | Date | Website |
| --- | --- | --- | --- | --- | --- |
| Infinity AI | Infinity AI is a technology startup that builds AI models faster with synthetic data. The startup's parameterized generators provide complete control over synthetic data distributions such as body shape, skin tone, lighting conditions, camera angles, and other factors. Its engineers can upload a single real-world video and turn it intohundreds of identical and perfectly labeled synthetic videos using the platform. Infinity uses a combination of physics-based simulations and generative techniques to do this.The company is based in San Francisco, California. | $5M | Seed | Dec 15, 2022 | https://infinity.ai/ |
| deepset | deepset builds the technology enterprises rely on to create custom, production-ready AI applications. We are the company behind Haystack, the leading open-source AI orchestration framework, and the deepset AI Platform for building mission-critical AI agents and applications. Since 2018, we’ve helped organizations such as Siemens, Airbus, TheEconomist, and the German Armed Forces bring the latest in large language models and NLP into real-world use, delivering proven open-source technology and enterprise-grade solutions adopted by thousands of AI teams worldwide. | $14M | Series A | Apr 28, 2022 | https://deepset.ai |

2 of 2 investments shown.

## Co-investors
- [Acequia Capital (AceCap)](https://shizune.co/investors/profile/acequia-capital) — VC Fund, 1 deal together
- [Google Ventures](https://shizune.co/investors/profile/google-ventures) — VC Fund, 1 deal together
- [Harpoon](https://shizune.co/investors/profile/harpoon-2271) — VC Fund, 1 deal together
- [Lunar Ventures](https://shizune.co/investors/profile/lunar-ventures) — VC Fund, 1 deal together
- [Matrix](https://shizune.co/investors/profile/matrix-partners) — VC Fund, 1 deal together
- [System.One](https://shizune.co/investors/profile/system-one-3) — VC Fund, 1 deal together

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### Similar stage
- [Antler](https://shizune.co/investors/profile/antler-be9c) — VC Fund
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- [Alumni Ventures](https://shizune.co/investors/profile/alumni-ventures-group) — VC Fund

## FAQ

### What does Alexander Ratner invest in?

Alexander Ratner invests primarily in Artificial Intelligence, Database and Open Source startups, most often at Seed and Series A stage. Most of the 2 investments tracked by Shizune back companies in Germany. The Investment Focus section breaks down every industry, stage and country in the portfolio.

### How do I contact Alexander Ratner?

Public channels for Alexander Ratner 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 Alexander Ratner last invest?

The most recent investment recorded for Alexander Ratner closed in Dec 2022. Shizune tracks 2 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 Oct 2026 and is updated monthly. Spotted something off? Use the “Suggest an edit” link near the top of the page.

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