Brookmd – streaming Markdown renderer in Rust (web, RN, Swift and more)

Brookmd, a streaming Markdown renderer built with a single Rust core, has been released for web, React Native, Swift, and Kotlin platforms. The engine uses incremental parsing with speculative closure for mid-stream constructs and stable block identities to avoid re-reconciling unchanged blocks, compiling to WASM for the web and native libraries for mobile and desktop. It is 100% CommonMark 0.31 + GFM compliant and emits a versioned JSON wire format byte-for-byte across all boundaries.

Streaming markdown for every platform. One Rust core — incremental parse with speculative closure for mid-stream constructs, stable block identities so unchanged blocks never re-reconcile — compiled to WASM for the web and to native libraries for mobile and desktop. Every boundary emits the same versioned JSON wire, byte-for-byte. 100% CommonMark 0.31 + GFM. In the browser, wire each LLM stream to a BrookClient and the markdown renders incrementally off the main thread , block by block — so many concurrent streams render without melting the UI thread. Live demo · · Full docs & API → /siinghd/brookmd/blob/main/packages/brookmd/README.md Changelog /siinghd/brookmd/blob/main/packages/brookmd/CHANGELOG.md npm i brookmd js import { BrookMarkdown } from "brookmd/react"; // stream is an AsyncIterable<string SSE deltas , a Response, or a ReadableStream <BrookMarkdown stream={stream} / ; Off the main thread — a pooled Web Worker per stream; the parser re-parses only the active tail on each token, patches cross the worker boundary as verified splices emitted bytes stay O n even for one giant growing block — wire delta mode, contract v1.2.0 , and heavy renderers highlighting, math, mermaid defer until a block closes. SSR-safe — imports and renderToString cleanly on the server across React, Vue, Solid, and Svelte; the worker is created lazily on the client. Structured block.data channel opt-in, default off — tables, headings, code, math, and lists are exposed as typed, streaming data on block.kind.data , so you build toolbars sort/filter/CSV , tables of contents, charts, and copy buttons from data — no HTML re-parsing, no AST tree to walk. Renderers for every stack — React, Vue 3, Svelte 4 & 5 , Solid, a framework-agnostic <brook-markdown Web Component, and a vanilla DOM mount on the web; a React Native renderer and Swift/Kotlin/Flutter bindings over the native core experimental — see Platforms platforms . Zero runtime dependencies. The whole engine is one WASM binary plus a small TypeScript client. See the package README for the full API, per-stream config, framework bindings, security model, and scaling helpers virtualize , stickToBottom .| Path | What | |---|---| packages/brookmd | crates/brookmd-core crates.io https://crates.io/crates/brookmd-core ; compiled to WASM for the npm package. Emits the versioned JSON wire contract /siinghd/brookmd/blob/main/crates/brookmd-core/WIRE.md . crates/brookmd-ffi crates/brookmd-cabi packages/brookmd-react-native experimental . https://www.npmjs.com/package/brookmd-react-native brookmd-react-native packages/brookmd-flutter bindings/kotlin bindings/swift web md.hsingh.app https://md.hsingh.app/ .The same Rust core streams the same versioned JSON wire WIRE.md /siinghd/brookmd/blob/main/crates/brookmd-core/WIRE.md across every boundary; golden tests pin every binding to byte-identical output. | Platform | Use | Status | |---|---|---| | Browser / Node / SSR | brookmd | Stable — published on crates.io https://crates.io/crates/brookmd-core brookmd-core Stable — published on npm — native parser via JSI, RN renderer https://www.npmjs.com/package/brookmd-react-native brookmd-react-native — SPM package /siinghd/brookmd/blob/main/bindings/swift bindings/swift BrookMd over an XCFramework — Android library + uniffi bindings /siinghd/brookmd/blob/main/bindings/kotlin bindings/kotlin over the C ABI /siinghd/brookmd/blob/main/packages/brookmd-flutter packages/brookmd-flutter + /siinghd/brookmd/blob/main/crates/brookmd-cabi crates/brookmd-cabi include/brook md.h Swift/Kotlin/C-ABI bindings ship prebuilt from CI as checksummed release assets https://github.com/siinghd/brookmd/releases Android .so per ABI, Apple XCFrameworks with iOS + macOS slices ; the React Native package vendors its binaries in the npm tarball. bun install bun run build:wasm compile the Rust core → WASM cd packages/brookmd && bun test CI enforces the CommonMark 652/652 + GFM conformance floors, the JS test suite, a fresh-process SSR cold-import check, and that the published tarball ships the WASM.