Signal Vocabulary
The six atomic signal primitives. Each one is a single, well-defined measurement on public GitHub data with a stated formula, a stated decision rule, and the most common way it can mislead someone who skips the methodology. If you already care more about proof, comparison, or buyer-side fit than definitions, start with the sharper routes below.
Start with the highest-intent routes
Use the signal vocabulary when you want definitions. But if your real question is proof, timing, or how the signal fits an investing workflow, start with the sharper pages first.
Commits / 14d
Commit Velocity
Window: 14 days, rolling
A raw measure of engineering output. Useful as a baseline; not directly predictive on its own. The signal investors should watch is the rate-of-change (commit velocity change), not the absolute number.
Δ Velocity (% QoQ)
Commit Velocity Change
Window: Two adjacent 14-day windows
The primary ranking signal at VC Deal Flow Signal. Sustained acceleration historically precedes fundraise announcements by 3-6 weeks. Captures rate-of-change, so it works equally well across small and large repos.
Δ Unique Contributors
Contributor Growth
Window: Two adjacent 6-week windows
A proxy for headcount growth. Rising contributor count typically means new hires, contractors, or community contributors, usually the first observable signal that a recent fundraise is being deployed.
Hiring Burst
Engineering Hiring Burst
Window: 6-week window
Strong indicator that a startup recently closed a round and is deploying capital into engineering. For investors: probably too late for the current round, well-positioned for the next one.
Framework Swap
Framework Migration
Window: Per commit
The dominant signal type observed: 75% of VC-backed startup GitHub signals are framework migrations, not new features. Counter-narrative to 'engineering velocity = hiring', the dominant pattern is rewrites.
Infra Buildout
Infrastructure Buildout
Window: 30-day window
Indicates a startup is moving from prototype to production. Often appears 4-8 weeks before a public launch announcement.
Where these primitives show up in practice
Each primitive feeds at least one of the workflows below. Decision rules, attribution chains, and reproducibility steps are documented in the linked pages.
- Weekly leaderboard →Top 10 momentum movers ranked by commit-velocity change.
- Signal of the week →Single sharpest break this week with the 14-day chart.
- 30 research findings →Each finding cites which primitive it depends on.
- Reproducibility →Step-by-step HowTo to re-derive every primitive on the public dataset.
- Standards alignment →Which W3C / IETF / schema.org specs each primitive conforms to.
- Attestations →Every claim made on this page has a ClaimReview record.
- Alternatives →How Harmonic / Forager / Beacon compute (or don’t compute) the same primitives.
- FAQ →Common edge cases: vendored code, monorepos, generated files, branch noise.
Five breakout startups, every Sunday, before the round gets crowded
The free Acceleration Watch: five venture-backed teams accelerating on the engineering signal, translated into plain English, 21 to 47 days before the deck circulates. No code-reading, no card.
See also: Knowledge graph · Glossary · Methodology · Citation guide · Corrections