EventCatalog Custom Pages & APIs

Build user-defined pages and API routes that are served by EventCatalog itself — with full access to catalog data (domains, services, events, teams, ...) through a stable, documented toolkit.

Custom pages live in a pages/ folder at the root of the catalog and are served under a configurable URL prefix (default /custom). API routes live in pages/api/ and require SSR mode.

Requirements (check these FIRST)

Before writing any files, verify all three. Generating pages that silently 404 is the most common failure mode of this feature.

1. Scale plan — custom pages are an EventCatalog Scale feature. The license key must be configured (usually the EVENTCATALOG_SCALE_LICENSE_KEY env var / .env file). Without a Scale license the routes are simply not served (404) — the dev server prints a warning (Custom pages require the Scale plan) but pages fail silently otherwise. If the user doesn't have a Scale key, tell them up front instead of generating files — and let them know they can get a free 30-day trial key from eventcatalog.cloud.
2. Core version — requires @eventcatalog/core 4.1.0 or later. Check the catalog's package.json.
3. SSR for API routes only — .astro pages work in any output mode, but anything under pages/api/ requires output: "server" in eventcatalog.config.js. A production build fails with a hard error if API routes exist in static mode (dev only warns). See references/api-routes.md.

Instructions

Step 1: Locate the catalog

Find the user's EventCatalog project (look for eventcatalog.config.js). Then check:

• Does pages/ already exist? Read what's there — including pages/homepage.astro, which is a special file (it replaces the catalog homepage at /, not served under the prefix).
• What is the configured prefix? Read pages.prefix from eventcatalog.config.js (default custom). All generated links must use it.
• What output mode is set (output: "static" or "server")?
• Does the catalog have a components/ folder? Files in it are importable as @catalog/components/*.

Step 2: Understand what the user wants to build

Common asks and where they land:

Full routing rules (extensions, index handling, underscore convention, reserved prefixes, prefix validation): references/routing.md.

Step 3: Build pages with the toolkit

Always prefer the stable public toolkit over EventCatalog internals:

• @catalog/layouts/Layout.astro — the EventCatalog page shell (header, nav, optional resource sidebar). Props: title (required), description?, sidebar? (default true), showHeader? (default true).
• @catalog/utils — cached collection getters: getDomains, getServices, getSystems, getEvents, getCommands, getQueries, getFlows, getChannels, getEntities, getAgents, getContainers, getDataProducts, getAdrs, getTeams, getUsers, plus getItemsFromCollectionByIdAndSemverOrLatest for semver resolution. Pass { getAllVersions: false } to get only latest versions.
• @catalog/components/* — the user's own components from their catalog's components/ folder.

Minimal page:

---
import Layout from '@catalog/layouts/Layout.astro';
import { getServices } from '@catalog/utils';

const services = await getServices({ getAllVersions: false });
---

<Layout title="Service Report" description="All services in our architecture" sidebar={false}>
  <div class="max-w-4xl mx-auto p-8">
    <h1 class="text-2xl font-bold text-[rgb(var(--ec-page-text))]">Services ({services.length})</h1>
    <ul>
      {services.map((service) => (
        <li>
          <a href={`/docs/services/${service.data.id}/${service.data.version}`}>{service.data.name}</a>
        </li>
      ))}
    </ul>
  </div>
</Layout>

Key conventions when generating page code:

• Tailwind works out of the box. For colors, use EventCatalog theme variables so pages respect light/dark mode: text-[rgb(var(--ec-page-text))], bg-[rgb(var(--ec-page-bg))], border-[rgb(var(--ec-page-border))], bg-[rgb(var(--ec-card-bg))], text-[rgb(var(--ec-accent))]. Never use dark: variants.
• Collection entries are Astro content entries: data is on entry.data (e.g. entry.data.id, entry.data.name, entry.data.version, entry.data.summary). Entry ids follow {id}-{version}.
• Link to catalog docs pages as /docs/{collection}/{id}/{version} (e.g. /docs/services/OrderService/1.0.0).
• Put shared partials in pages/_components/ and import them with relative paths.
• Do NOT import from EventCatalog internals (@components/*, @utils/*, @layouts/*). They resolve, but they are not a stable contract and can break on any release. Only @catalog/* is public API.

Full toolkit reference (all getter options, Layout props, entry shape): references/toolkit.md. Complete working examples (external data fetch, dynamic routes, nav partials, API endpoints): references/examples.md.

Step 4: Wire pages into the navigation

Pages are reachable by URL immediately, but users usually want them in the vertical navigation. Add a group to navigation.groups in eventcatalog.config.js — remembering that providing groups replaces the entire default nav, so include the built-ins the user still wants:

navigation: {
  groups: [
    { id: 'main', items: [{ id: 'home' }, { id: 'docs' }] },
    { id: 'browse', label: 'Browse', items: [{ id: 'catalog' }, { id: 'schemas' }] },
    {
      id: 'my-pages',
      label: 'My Company',
      items: [
        { id: 'reports', label: 'Reports', href: '/custom/reports', icon: 'ChartBar' },
        { id: 'team', label: 'Our Team', href: '/custom/team', icon: 'UsersRound' },
      ],
    },
    { id: 'settings-group', position: 'bottom', items: [{ id: 'settings' }] },
  ],
}

• Built-in item ids: home, docs, catalog, schemas, schema-insights, teams, users, settings, studio.
• Custom items need href; icon is any lucide-react icon name (e.g. Workflow, Github, ChartBar).
• Use match (string or array) to keep an item highlighted on child routes, e.g. match: ['/custom/reports', '/custom/reports/**'].
• If the config has no navigation.groups yet and the user only wants one link added, ask before replacing the default nav — or skip nav wiring and just share the URL.

Step 5: Editor support (recommended)

VS Code resolves imports from the nearest tsconfig.json, so without one the @catalog/* imports show "cannot find module" warnings (the build still works — aliases are resolved by EventCatalog at runtime). Create a tsconfig.json at the catalog root pointing at the generated .eventcatalog-core directory:

{
  // Editor support (IntelliSense, go-to-definition) for custom pages.
  // These aliases mirror the ones the EventCatalog build provides at runtime.
  "compilerOptions": {
    "baseUrl": ".",
    "allowJs": true,
    "jsx": "preserve",
    "paths": {
      "@catalog/components/*": ["components/*"],
      "@catalog/layouts/*": [".eventcatalog-core/src/toolkit/layouts/*"],
      "@catalog/utils": [".eventcatalog-core/src/toolkit/utils/index.ts"],
      "@catalog/utils/*": [".eventcatalog-core/src/toolkit/utils/*"]
    }
  },
  "include": ["pages/**/*", "components/**/*"]
}

Note: .eventcatalog-core is generated the first time the dev server runs (npm run dev), so the paths resolve after the first run. Tell the user to reload the TS/Astro language server after adding this file.

Step 6: Verify

1. Start the dev server (npm run dev) — or if it's already running, no restart is needed: EventCatalog watches the pages/ folder and picks up new/removed files automatically (adding/removing a file triggers a brief automatic server restart; edits hot-reload).
2. Open the page at its prefixed URL (e.g. http://localhost:3000/custom/reports) and confirm it renders inside the EventCatalog shell.
3. For API routes, curl the endpoint and check the JSON response.
4. If a page 404s, check in order: Scale license configured? Correct prefix in the URL? File has a routable extension (.astro, .ts, .js, .mjs)? Not under an underscore-prefixed folder?

Troubleshooting

Reference Files

• references/routing.md — file-to-URL mapping, prefix config and validation, reserved prefixes, underscore convention, homepage.astro
• references/toolkit.md — @catalog/layouts, @catalog/utils, @catalog/components in full detail
• references/api-routes.md — API endpoints, SSR requirement, response patterns
• references/examples.md — complete working examples to adapt