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    Step Function

    Boston, Massachusetts, United StatesFounded 2023
    www.stepfunction.vcLinkedIn
    AIData & AnalyticsCybersecurityDeveloper ToolsInfrastructure & CloudEnterprise Software

    Step Function is an early-stage venture capital firm based in Boston, founded by Will Lehmann. The firm invests first checks in technical founders building enterprise infrastructure software, with focus areas including data/AI infrastructure, cybersecurity, and developer tools.

    43% of their portfolio is in Developer Tools. Their most common stage is seed (43% of deals). Average disclosed round size is $11.1M (across 6 rounds with reported amounts).

    Find people at Step Function on Goldilocks AI

    Portfolio

    6

    Fund Size

    —

    Top Stage

    Seed

    Last 12 Mo

    0

    Team

    WL

    Will Lehmann

    Founder & GP

    Portfolio Breakdown

    Stage Distribution

    Sector Distribution

    Investment Activity

    DealsAvg Round Size

    Portfolio

    7 investments
    CompanyRoundAmountDate
    Nebulock logoNebulockSeries A$25MJan 2026
    Zephyr Cloud logoZephyr CloudSeed$3.5MSep 2024
    Proof logoProofPre-Seed—Jun 2024
    Unkey logoUnkeySeed$4.5M—
    Proofs logoProofsPre-Seed$2.6M—
    Nebulock logoNebulockSeries A$25M—
    Nebulock logoNebulockSeed$6M—

    Top Co-Investors

    Zetta Venture Partners3 shared
    Bain Capital Ventures3 shared
    Decibel3 shared
    Expeditions2 shared
    RTP Global2 shared
    Bek Ventures2 shared
    In-Q-Tel2 shared
    FirstMark Capital2 shared
    Night Media1 shared
    Nina Capital1 shared
    True Ventures1 shared
    Sunflower Capital1 shared
    Uncork Capital1 shared
    Tokyo Black1 shared
    PWV1 shared
    K5 Global1 shared
    Essence VC1 shared
    Robin Capital1 shared

    Last updated: 7 October 2026