Flow
A static typechecker for JavaScript
Flow launched on June 2, 2017 with 8 votes, #1,003 of 3,107 launches that month and more than 50% of that year's launches. The site was still online in September 2026, 9 years on.
What it does
Flow is a static typechecker for JavaScript. To find out more about Flow, check out flow.org.
Flow is a typed dialect of JavaScript — a static type system plus first-class language constructs, built for safety and scale.
It looks like TypeScript now. Plus component / renders / match . And still safer. Is it Flow or TypeScript? You can't tell. Flow has keyof , readonly props, unknown , indexed access types T[K] , and extends generic bounds. Plus conditional types, mapped types, and type guards. More TS-compatible syntax → component and renders are built into Flow's syntax. Props are named parameters, typed inline with defaults, so there's no props object to annotate or destructure. Only components that render Header can flow into a renders Header prop: design-system composition rules become type errors instead of bugs caught in review. More on component and renders → match is both an expression (shown here)…from flow.org
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FlowTracker – Track data flowing through Java programs2024 · github.com · ▲280FlowTracker, a Java agent that tracks data flowing through Java programs. It helps you understand where any program got its output from, what it means, and why it wrote it. Watch the video or explore the live demo yourself, and read how it works at https://github.com/coekie/flowtracker
Flows2024 · flows.sh · ▲239If you’ve ever tried building onboarding or product adoption with Appcues, Chameleon, Userflow, WalkMe, or Usetiful, you’ve probably hit the same two problems: 1. Everything is rendered with JavaScript overlays 2. Customization is a nightmare A little backstory: When I was choosing an onboarding tool for my previous project, nothing matched what I needed. So I had to build my own. With help from IntroJS I built onboarding solution that I needed: Tooltips, Modals, custom CSS, waiting for interactions, and saving the state into the database. It worked… but it took way more time than it should…
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