sergiodxa/monorepo

The products, sites and open-source toolkit of Sergio Xalambrí, in one repository.

This is everything I build and run: a monitoring service, a feed reader, a book storefront, an identity provider, my personal site, and the 100+ TypeScript packages they're made of. Every app runs on Cloudflare Workers with Remix v3, every package is published to npm under @sdxc, and all of it shares one toolchain, one set of conventions and one test suite.

Use the apps, borrow the packages, or read the code to see how a full product is put together on the edge.

• 🌐 Products: Uptime · Reader · Books
• 📦 Packages: sdxc.dev
• ✍️ Blog: sergiodxa.com

Products

Uptime — uptime.sergiodxa.com

Know your site is down before your customers do. Uptime watches HTTP endpoints, DNS records, TCP ports, SSL certificates and scheduled jobs, runs multi-step flow checks, and alerts your team through the channels it already uses. It includes public status pages, maintenance windows, response-time analytics, team access and a REST API. Try it on any URL from the landing page, no account needed.

Reader — reader.sergiodxa.com

Follow any site that publishes RSS or Atom and read everything in one place. Each feed is refreshed at the pace it actually publishes, posts are searchable with a real query syntax, and posts you want to come back to stay on a saved shelf. Paid plans add labels, filter rules, the full article fetched into the app, and an MCP endpoint so your agent can read along too.

Books — books.sergiodxa.com

The home of the React Router OAuth2 Handbook: a free sample chapter, live pricing, and an upgrade path for readers who started with an earlier edition.

Sites and Services

In the Workshop

Projects under active development, published here as they take shape.

• auth-saas: a multi-tenant identity platform where every customer gets their own isolated OpenID Connect provider on their own domain.
• pkmn: a monster-collecting game engine that keeps content, rules and presentation apart, so anyone can build their own game by writing data.
• demo: a job board built for a Remix v3 conference talk, runnable fully offline.

Packages

The packages are the building blocks the apps above are made of, extracted so anyone can use them. They are small, focused and written to the spec they implement, built on fetch, Request/Response and Web Crypto so most run unchanged on Cloudflare Workers, Bun, Deno and Node. Fallible operations return a typed Result instead of throwing.

A few of them, in the shape they share: declare something once as typed data, then map behavior onto it.

@sdxc/authz: permissions as a typed catalog of abilities, granted by roles and checked synchronously.

import { abilities, ability, allow, context, definePolicy, fact } from "@sdxc/authz";
import { isSuccess } from "@sdxc/result";

let catalog = abilities({
	article: {
		read: ability({ context: context<{ article: Article }>("article"), deniedAs: "notFound" }),
		update: ability({ context: context<{ article: Article }>("article") }),
	},
});

let policy = definePolicy(catalog, {
	facts: { actor: fact<{ id: string }>() },
	everyone: [
		allow("article.read", { when: { op: "eq", field: "article.published", value: true } }),
	],
	roles: {
		author: [
			allow("article.update", { when: { op: "eq", field: "article.authorId", path: "actor.id" } }),
		],
		admin: { inherits: ["author"], grants: [allow("*")] },
	},
});

let access = policy.for({ roles: ["author"], facts: { actor: user } });
if (isSuccess(access)) access.data.can(catalog.article.update, { article }); // true for their own

@sdxc/jobs: background jobs declared in one map, with typed payloads, cron schedules, retries and a pluggable queue.

import { createJobDispatcher, createJobHandler, job, jobs } from "@sdxc/jobs";
import * as cloudflare from "@sdxc/jobs/cloudflare";
import * as s from "remix/data-schema";

let catalog = jobs({
	sendWelcome: job({ input: s.object({ userId: s.string() }) }),
	digests: { daily: job({ cron: "0 8 * * *" }) },
});

export default createJobHandler(catalog.sendWelcome, async (ctx) => {
	await sendWelcomeEmail(ctx.input.userId); // ctx.input is typed from the schema
});

let dispatcher = createJobDispatcher({ logger, queue: cloudflare.queue(() => env.QUEUE) });
dispatcher.map(catalog.sendWelcome, () => import("./jobs/send-welcome"));

await dispatcher.enqueue(catalog.sendWelcome, { userId: user.id });

@sdxc/mcp: an MCP server for your agent-facing API, served over stateless Streamable HTTP from any fetch handler.

import * as s from "@sdxc/json-schema";
import { createHandler, tool, tools, ToolError } from "@sdxc/mcp";

let toolset = tools({
	search: tool("search_documents", {
		description: "Searches published documents by title, excerpt and tags.",
		input: s.object({ query: s.string() }),
		annotations: { readOnlyHint: true },
	}),
});

let mcp = createHandler({ name: "documents", version: "1.0.0" });

mcp.tools.map(toolset.search, async (ctx) => {
	let documents = await search(ctx.input.query);
	if (documents.length === 0) throw new ToolError("Nothing matched. Try a broader query.");
	return documents;
});

export default { fetch: mcp.fetch };

Versions are calendar dates (2026.9.4), released daily from whatever changed, and packages released together are pinned to each other so they always work together. Guides and API references live at sdxc.dev.

Everything at Once

Authentication and Identity

Security and Abuse Prevention

HTTP, APIs and Routing

Jobs, Messaging and Product Infrastructure

Content, Feeds and the Social Web

Formats and Parsers

Cloudflare

UI and Internationalization

Foundations

How It's Built

• One stack everywhere. Remix v3 for routing and server-rendered UI, Cloudflare Workers for hosting, D1 and Durable Object SQLite for data, Queues for background jobs.
• Packages first. When two apps need the same thing, it becomes a package with its own README, tests and npm release. The apps stay thin and product-focused.
• Tested against the real platform. Tests run under Vitest, and tests that touch KV, D1 or R2 run inside workerd with real Cloudflare bindings instead of hand-written stubs.
• Decisions on the record. Significant architectural choices are written up as Architecture Decision Records, so the reasoning travels with the code.
• The platform does the work. Dialogs, popovers and disclosures use native HTML, and JavaScript is reserved for what the browser can't do on its own.

Working on the Repository

You need Bun and Node.js 22.5 or newer.

bun install
bun check
bun run test

bun check formats, lints and type checks everything in one pass, and bun run test runs every test. To run an app locally, cd apps/<name> and bun run dev; each app's README lists its setup. The conventions the codebase follows are written down in AGENTS.md.

License

The packages are MIT licensed. The applications are licensed under the O'Saasy License: you can self-host them for personal or internal use, but not offer them as a competing hosted service. Names, logos and site content are not covered by either license. See LICENSE.md for the details.