Menlo Park, CA · Founded 2010 · Privately Held (backing)
Manufacturer of linear power generators intended to bring affordable, reliable, and net-zero carbon grids of the future. Mainspring is based in Menlo Park, CA and was founded in 2010. Its last reported valuation was $1.9 billion in Apr 2025. It has raised $849 million.
Last reported valuation
$1.9B
Oct 2026
Priced at
—
Total raised
$849.5M
Last round
—
Cap table — not yet on record
Mainspring's share-class structure hasn't surfaced in our sources yet. Cap tables are assembled from certificates of incorporation, round filings, and disclosures as they land.
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·The complete investor list: 37 names
·Watch Mainspring: the Monday email on marks, rounds and moves
