Series A AI companies in San Francisco

Companies building AI products, foundation models, and applied ML platforms. Filtered to Series A-stage companies headquartered in San Francisco.

Built from a search like: “Top Series A AI companies in San Francisco”

Ranked by current headcount across Series A AI companies in San Francisco. Refreshed daily.

1
Genentech· South San Francisco, California, United States
- Series A
- 18.1k employees
- Founded 1976
2
Xaira Therapeutics· South San Francisco, California, United States
- Series A
- 192 employees
- Founded 2023
3
Redrob· San Francisco, California, United States
- Series A
- 148 employees
- Founded 2018
4
iZumi· South San Francisco, California, United States
- Series A
- 92 employees
- Founded 2007
5
BIOMAKERS· San Francisco, California, United States
- Series A
- 77 employees
- Founded 2014
6
Addition Therapeutics· South San Francisco, California, United States
- Series A
- 64 employees
7
Arena· San Francisco, California, United States
- Series A
- 58 employees
- Founded 2025
8
OneSkin· San Francisco, California, United States
- Series A
- 57 employees
- Founded 2016
9
TRexBio· South San Francisco, California, United States
- Series A
- 56 employees
- Founded 2018
10
Parker Institute for Cancer Immunotherapy· San Francisco, California, United States
- Series A
- 51 employees
- Founded 2016
11
SonoThera· South San Francisco, California, United States
- Series A
- 49 employees
- Founded 2021
12
Until· San Francisco, California, United States
- Series A
- 46 employees
- Founded 2024
13
Vilya· South San Francisco, California, United States
- Series A
- 45 employees
- Founded 2022
14
Tenvie Therapeutics· South San Francisco, California, United States
- Series A
- 43 employees
- Founded 2025
15
Shinobi Therapeutics· South San Francisco, California, United States
- Series A
- 41 employees
- Founded 2023
16
Rezo Therapeutics· San Francisco, California, United States
- Series A
- 40 employees
- Founded 2021
17
Gordian Biotechnology· South San Francisco, California, United States
- Series A
- 39 employees
- Founded 2018
18
Wherobots· San Francisco, California, United States
- Series A
- 36 employees
- Founded 2023
19
SyntheX· San Francisco, California, United States
- Series A
- 34 employees
- Founded 2016
20
Nudge· San Francisco, California, United States
- Series A
- 33 employees
- Founded 2024
21
Mission Barns· San Francisco, California, United States
- Series A
- 32 employees
- Founded 2018
22
Switch Therapeutics· San Francisco, California, United States
- Series A
- 30 employees
- Founded 2020
23
Atomic AI· South San Francisco, California, United States
- Series A
- 30 employees
- Founded 2021
24
3T Biosciences· South San Francisco, California, United States
- Series A
- 29 employees
- Founded 2017
25
CIONIC· San Francisco, California, United States
- Series A
- 29 employees
- Founded 2018

Find engineers at Series A AI companies in San Francisco

Searching for “engineers at top Series A AI companies in San Francisco” surfaces this slice of the market. The list above ranks AI companies headquartered in San Francisco whose latest disclosed round is Series A, by current headcount, drawn from public LinkedIn and Crunchbase records. With 55 matching companies in our index, this is a tight read on where the AI talent in San Francisco is heating up.

Three filters at once narrows the field hard. The companies that survive all three — Series A, AI, in San Francisco — are usually the most targeted recruiting pool a hiring manager can ask for. Senior engineers, founding designers, and product leads here are about to become AI’s next operators and angel investors.

Refolk converts this list into a live search. Ask for “senior engineers at Series A AI companies in San Francisco hiring” or “founders of Series A AI companies in San Francisco who left in the last year” and Refolk returns a ranked shortlist with the evidence behind each match.

How this list is built

Refolk pulled AI companies headquartered in San Francisco whose latest disclosed funding round is Series A from public LinkedIn and Crunchbase records, ranked them by current employee count, and kept those with at least 3 employees. The list refreshes once a day.

Last refreshed: Thu, 07 May 2026 07:19:00 GMT

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