Corelight raises $25M Series B led by General Catalyst to grow its network security platform, which is based on the open-source Bro project
Context & Ripple Effects
Corelight's arc starts with its $9.2M Series A led by Accel in 2017, positioning the company as an enterprise answer to ransomware by commercializing Bro, the open-source network traffic analysis project. The $25M Series B brings General Catalyst in alongside Accel to fund that build-out.
The bet compounds quickly: within two years Corelight raises a $50M Series C, then a $75M Series D, and by 2024 a $150M Series E at a $900M valuation with roughly $100M ARR in sight — making this 2018 round the point where the open-source-to-platform thesis first attracted a second major firm.
First-order effects
- Corelight gets the capital to grow headcount and product around its Bro-based network traffic analysis platform, moving from ransomware-focused messaging toward a broader enterprise security offering.
- General Catalyst becomes a named backer alongside Accel, adding a second institutional validator to a company still two years away from its Series C.
Second-order effects
- A venture-backed company shipping a hardened, supported version of an open-source sensor raises the bar for enterprises choosing between free Bro deployments and paid platforms, pressuring rivals in network detection to articulate why their proprietary approach wins.
- For General Catalyst, the round adds an early enterprise-security position that later sits alongside its much larger portfolio scale — the firm reported over $40B in assets under management by summer 2025 after raising $8B in 2024.
Third-order effects
- If the pattern holds, open-source security infrastructure projects keep converting into venture-scale platforms, with early commercializers capturing the enterprise market the community project seeded.
- Repeat-backer dynamics concentrate late-stage security funding: Accel's lead on both the Series A and the eventual Series E shows how first believers compound ownership across a company's full funding ladder.
The trend: Open-source network security projects are being converted into venture-backed enterprise platforms, with early investors like Accel and General Catalyst compounding positions across successive rounds.