Company record
Rein
Updated October 26, 2026 · Presspool
Rein is a runtime security platform that discovers and secures every AI agent, MCP server and AI app an enterprise runs. reinsec.io
Funding
Latest announced financing: $25 million, Series A, led by Glilot Capital and Sienna Venture Capital, announced October 8, 2026.
- $25 million Series A, announced October 8, 2026. Led by Glilot Capital and Sienna Venture Capital. Brings total funding to $35 million; Corner Ventures also participated. Listed in the AI startup funding roster for October 5–10, 2026. Sources: Rein Security blog, FinSMEs.
Of the 58 Series A rounds with exactly stated amounts in dollars on Presspool's weekly rosters since September 21, 2026, Rein's $25 million is the joint 26th largest; their median is $21.5 million.
Whether AI names Rein
- On the AI security map: named or cited in 2 of 55 answers to Presspool's AI security questions on October 26, 2026 (ChatGPT 1 of 8, Claude 0 of 8, Perplexity 1 of 8, Gemini 0 of 8, Copilot 0 of 8, Google AI Mode 0 of 8, Google AI Overviews 0 of 7). See the map. Of the 16 companies on the map, Rein ranked joint 11th by answers naming or citing it in that sample. The other companies AI names most on AI security questions: HiddenLayer (22 of 55), Zenity (22 of 55), Mindgard (15 of 55), WitnessAI (11 of 55), Noma Security (10 of 55) and Pillar Security (10 of 55). Most often named in the same answers: HiddenLayer (2), Reco (2), Zenity (2), Harmonic Security (1), Mindgard (1).
- Machine Relations Index: Not cited in any Machine Relations Index answer, May 10, 2026 to October 18, 2026.
Week by week
Answers that named or cited Rein in each weekly sample of Presspool's AI security questions, by the Monday of the sample week. A row is added every week.
| Week of | AI security |
|---|---|
| October 19, 2026 | 4 of 53 |
| October 26, 2026 | 2 of 55 |
Related records
Also on the AI security map: Giskard, Harmonic Security, HiddenLayer, Kontext, Lasso Security, Mindgard, Noma Security, Opsin, Outerlimit, Palma.ai, Pillar Security, Reco, Straiker, WitnessAI, Zenity.
Closest rounds in the roster for October 5–10, 2026: Flai ($27 million Series A, October 6, 2026), Vitalize ($31 million Series A, October 6, 2026), OneByZero ($20 million Series A, October 5, 2026), Vocca ($20 million Series A, October 5, 2026), Avarra ($17 million Series A, October 6, 2026), Siena AI ($17 million Series A, October 6, 2026).