Small TypeScript packages built on web standards.

Take one, or take the set. There are 60 of them, written for Remix on Cloudflare Workers: Request and Response in, typed values out. 37 of them need neither.

Read the docs Browse the packages

Failure is a value, not a control flow

A handler that composes three of them, and never throws.

import { Markdown } from "@sdxc/markdown";
import { badRequest, ok } from "@sdxc/response";
import { isFailure } from "@sdxc/result";

export async function handler(request: Request) {
	let result = Markdown.parse(await request.text(), { frontmatter: Frontmatter });
	if (isFailure(result)) return badRequest({ line: result.error.position?.start.line });
	return ok(result.data.frontmatter);
}

What holds the set together

Web standards first

Request, Response, Web Crypto, Intl and Standard Schema — the platform, not a shim over it.

Errors are values

Every fallible entry point answers with a Result, so nothing throws past you and the failure carries where it happened.

Nothing you didn't ask for

Subpath exports keep what you skip out of your bundle, and 31 packages pull in nothing from outside the collection at all.

Built for Remix, not bound to it

23 target Remix directly, because that is what they are written for. The other 37 depend on no framework and run anywhere fetch does.

The packages, by the problem they solve

HTTP & responses

@sdxc/http
Response builders, content negotiation, and HTTP caching for the Fetch API
@sdxc/response
Semantic helpers that build Response objects for JSON APIs and redirects
@sdxc/api-client
Base class for clients of a remote HTTP API: one origin, path-relative verb methods, shared hooks
@sdxc/pagination
Offset and keyset pagination with parameter parsing and Link headers
@sdxc/server-timing
Server-Timing measurements collected per request and written to a response header
@sdxc/catch-response-middleware
Router middleware that turns a thrown Response into the request's response
@sdxc/get-client-ip
Read the client IP from a Cloudflare Workers request
@sdxc/user-agent
Read a User-Agent string into its browser, engine, operating system and device

Identity & security

@sdxc/auth
OAuth 2.0 and OpenID Connect client for any runtime that speaks Request and Response
@sdxc/jwt
JWT payload classes and the keys that sign them
@sdxc/passkey
Passkeys on both sides: a one-call WebAuthn browser API and a relying party that verifies the ceremonies
@sdxc/saml
SAML 2.0 service provider: verify a signed assertion, build the requests and metadata around it
@sdxc/crypto
Web Crypto primitives — hashing, HMAC, tokens, TOTP, AES-GCM — plus scrypt passwords
@sdxc/webhooks
Sign and verify Standard Webhooks deliveries, reporting every failure as a typed value
@sdxc/uuid
Validate, assert and generate UUIDs behind a branded UUID type
@sdxc/typeid
Type-safe TypeID values: a UUID and the prefix that names what it identifies

Content & formats

@sdxc/markdown
GitHub Flavored Markdown: parse to a typed AST, transform it, write it back
@sdxc/yaml
YAML reading and writing over a documented subset, shaped after the built-in JSON object
@sdxc/xml
XML parser and serializer for RSS-style feeds
@sdxc/html
Read a served page: fetch or parse HTML, then query it by role and accessible name
@sdxc/rss
RSS 2.0 feed builder and parser
@sdxc/atom
Atom 1.0 feed parser and builder
@sdxc/json-feed
JSON Feed 1.1 builder and parser
@sdxc/feed
One feed API over RSS, Atom and JSON Feed, with conditional fetching and autodiscovery
@sdxc/opml
Read and write OPML subscription lists
@sdxc/sitemap
Read and write the sitemap protocol: collect URLs, or fetch a published sitemap
@sdxc/distill
Distill the article out of a web page: fetch under bounds, score the candidates, sanitize what is left

Data & storage

@sdxc/cache
Cache contract with adapters for memory and Cloudflare KV
@sdxc/workers-cache
Cache tags, purging and cache-status reads for Cloudflare Workers Cache
@sdxc/session-storage-kv
A remix/session SessionStorage backed by a Cloudflare Workers KV store
@sdxc/data-table-d1
A remix/data-table DatabaseDriver backed by Cloudflare D1
@sdxc/data-table-sqlstorage
A remix/data-table database driver backed by a Cloudflare Durable Object's SQL storage

Interface

@sdxc/ui
Styled, accessible remix/ui components rendered as server HTML
@sdxc/u
Utility-first styling for remix/ui, composed from small, terse mixins
@sdxc/icons
Lucide icons as remix/ui components, one tree-shakeable export per icon
@sdxc/i18n
Language detection, i18next instances and translated-markup components
@sdxc/seo
Canonical URLs, typed schema.org structured data and head metadata
@sdxc/highlight
Syntax highlighting that returns tokens rather than markup, with a markdown walk visitor and a stylesheet keyed to the token types
@sdxc/lazy-route
Maps a route to a module imported on the first request that reaches it

Operations

@sdxc/jobs
Declared background jobs dispatched over a pluggable queue backend
@sdxc/cron
Cron schedules with zone-aware occurrences and descriptors
@sdxc/logger
One wide event per Worker invocation, attached at the router and the job dispatcher
@sdxc/rate-limit
Adapter-based rate limiting with standard response headers
@sdxc/flags
Feature flag evaluation implementing the OpenFeature specification
@sdxc/flags-engine
Flag evaluation engine: typed targeting rules, percentage splits and pluggable stores
@sdxc/billing
Vendor-neutral billing: one provider contract every payment platform is reached through, plus a webhook endpoint that verifies and deduplicates deliveries
@sdxc/mail
Transport-agnostic transactional email with pluggable transports and remix/ui rendering
@sdxc/hostname
Cloudflare for SaaS custom-hostname client: register, poll and delete customer domains
@sdxc/mcp
Model Context Protocol servers as remix/router actions, served over stateless Streamable HTTP

Language & values

@sdxc/result
Result type for error handling
@sdxc/types
Shared TypeScript types
@sdxc/dates
Zone-aware date operations with Intl-only formatting
@sdxc/duration
Typed duration strings converted to milliseconds or seconds
@sdxc/strings
English inflection, Chicago title case, slugs and grapheme-safe text
@sdxc/semver
SemVer 2.0.0 parsing, precedence ordering and range-free version comparisons
@sdxc/location
URL-like Location class for URL paths without an origin
@sdxc/validate
Standard Schema validation utilities

Testing

@sdxc/spec
Executable specification runner for .spec files
@sdxc/sample
Seeded generation of believable people, places, prose, numbers and identifiers
@sdxc/cloudflare-mocks
In-memory, behavior-accurate Cloudflare binding mocks for tests

Three worth the detour

Each of these does something you cannot get by reaching for another package.

@sdxc/spec

Executable specifications, written in a language with no if and no loops, run in a fresh workspace under permissions you grant by name.

grant fs.write to "build/"
run "bun run build"
expect file "build/index.js" to exist

@sdxc/u + @sdxc/ui

Accessible components built on <dialog>, the Popover API and Invoker Commands, rendered as server HTML that works before any JavaScript loads.

<Dialog>
	<Dialog.Trigger>Open</Dialog.Trigger>
	<Dialog.Content>
		<Dialog.Title>Delete this monitor?</Dialog.Title>
	</Dialog.Content>
</Dialog>

@sdxc/markdown

GitHub Flavored Markdown to a typed AST you can walk, transform and write back. This page is one: the copy you are reading is a markdown file, and the sections are tags with attribute schemas.

let painted = Markdown.walk(document, highlight);

Install and pin

Versions are dates. A release published on the 21st of September 2026 is 2026.9.21, there is at most one a day, and a later date means a later release and nothing more — it promises no compatibility with the one before it.

So pin exactly, and move when you are ready to read what changed.

{
	"dependencies": {
		"@sdxc/result": "2026.9.21"
	}
}

Where to go next

Learning

Start with the guides — what these are, how to install them, and your first handler.

Browsing

Every package, filterable by name and by what it does.

Watching

What shipped, and when, one entry per release date, with the commits that went into it.

MIT licensed, and written by Sergio Xalambrí.