The Rust port is just the start. Flow in 2026 isn't like you remember: flow.org/

Most of the Rust port was done by a single engineer over ~8 months, while the rest of the team kept shipping features: no code freeze. Read the full story: medium.com/flow-type/flows-o…

Flow is now written in Rust 🦀 The migration from OCaml to Rust brought up to 2x faster type-checking on large codebases.

Yes, you can fix it by changing the code. If only there was a tool that would point out the problem in the first place - so you knew you had to make the fix 🤔

Doesn't seem like a good assumption 😬

Exactly, better to have your type-checker actually enforce you're doing the right thing and prevent your app from crashing! The actual Flow error message is longer and describes: - Either make `Array<string>` and `Array<LogLine>` the same - Or make array a `ReadonlyArray`

Flow catches the crash before you ship it. More examples where Flow is safer: flow.org/en/docs/flow-vs-typ…

TypeScript lets you pass Array<string> where Array<string | Error> is expected, so the function pushes an Error to your string array. Flow rejects it. TS Playground, 0 errors: typescriptlang.org/play/?#co… Flow Playground, rejects with an error: flow.org/try/#1N4Igxg9gdgZgl…

Crashes at runtime - but TypeScript accepts it: zero errors under strict. Can you spot the bug?

JavaScript Pattern Matching with `match`, available now: medium.com/flow-type/javascr…

Flow for TypeScript Users in 2026: 20+ side-by-side comparisons, verified against TypeScript 6.0.3 with 'strict' enabled: flow.org/en/docs/flow-vs-typ…

Another: TypeScript only validates the signature of a type-guard, not the body. Flow validates the body and rejects predicates that lie about what they check.

Where the two still diverge, Flow keeps the stricter, safer default. Extract a method off an instance and it loses its 'this' binding. TypeScript lets the extraction through, so tick() crashes without a valid 'this'. Flow rejects it right where 'this' is lost.

First-class component syntax for React. 'renders' types compose through wrappers - MainHeader renders Header slots anywhere a Header is expected, and unrelated elements are rejected.

Flow also has features TypeScript lacks. Pattern matching as an expression. It's exhaustively checked, with structural patterns that destructure as they match. Forget a case, like 'remove', and match flags it and tells you what to add.

TypeScript or Flow? 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.

If your "Flow vs TypeScript" take is from 2021, it's out of date. Flow looks like TypeScript now - but it has pattern matching and React component syntax, while catching runtime crashes TypeScript waves through. Examples below. 👇

SWC has added support for Flow: swc.rs/docs/usage/flow