Open source packages, crates, and templates from builder.group projects.

These packages live under packages/_deprecated. They remain listed for existing users and historical context, but they are not actively maintained. Prefer the active packages above when starting new work.

See /examples

• feature-fetch/vanilla/basic

• feature-form/react/basic

• feature-state/react/basic

• openapi-ts-router/hono/petstore
• openapi-ts-router/express/petstore

• xml-tokenizer/vanilla/playground

blgc stands for BuiLder.Group Community, chosen because similar names like blg, bldr and bgc were already taken.

Keeping all packages in one repository means shared tooling, consistent versioning, and streamlined CI. Cross-package changes are easier to make and keep in sync.

The trade-off is discoverability: individual packages are harder to find through search because they all live under one repo.

pnpm build (development): includes TypeScript declaration maps so IDE navigation goes to source files instead of compiled definitions, and skips minification for easier debugging.

pnpm build:prod (production): smaller output, minification enabled, declaration maps excluded. Declaration maps cause npm publish errors (e.g. EINVALIDTAGNAME in GitHub CLI) so they must be stripped from published packages.

A feature is a self-contained extension that adds typed methods or behavior to a host object via .with(). The host starts with a base API, and each .with(feature()) call extends it by adding methods, validating dependencies, and narrowing the TypeScript type. See feature-core for the underlying primitives.

The .with() chain (powered by feature-core) gives TypeScript inference per step. Each call narrows the type based on what was installed before it.

const $count = createState(0).with(undoFeature());

$count.undo(); // typed
$count.missing(); // type error

A declarative feature array like features: [featureA(), featureB()] cannot validate dependencies or accumulate types left-to-right as reliably.

This Medium post explains the key differences well.

Objects compose cleanly with the .with() model. Classes make that style of extension harder to type and harder to reuse across packages.