Remix implementation checklist

Ensure every route with a loader or action exports an ErrorBoundary to prevent server-side crashes from bubbling up to the root and breaking the entire application.

Identify slow third-party API calls or heavy database queries and move them to a deferred promise using the Remix 'defer' utility to improve Time to First Byte (TTFB).

Explicitly define Cache-Control headers in loader responses for static or slow-changing data to leverage CDN and browser caching.

Check that all dynamic route parameters (e.g., params.id) are validated using a schema library like Zod before passing them to database queries.

Throw a 404 Response object within loaders when a resource is not found to trigger the nearest ErrorBoundary with isRouteErrorResponse.

Implement Zod or Valibot schemas within action functions to validate all incoming FormData before processing mutations.

Verify that all non-GET requests are protected against CSRF using remix-utils or custom header verification if not using the built-in authenticity token patterns.

Use useNavigation to implement 'submitting' or 'loading' states on buttons and forms to provide immediate feedback during mutations.

Use useFetcher or useNavigation.formData to optimistically update the UI for high-frequency actions like toggling checkboxes or deleting items.

Disable submit buttons or implement server-side idempotency keys to prevent duplicate data entry on slow network connections.

Verify that session cookies are configured with 'httpOnly: true', 'secure: true', and 'sameSite: "lax"' (or "strict") in the createCookieSessionStorage settings.

Ensure the SESSION_SECRET environment variable is long, random, and not committed to version control.

Add a validation script in entry.server.tsx or a separate init file to throw an error if required production environment variables are missing.

Ensure that 'redirectTo' parameters in login or multi-step forms are validated against a whitelist to prevent Open Redirect vulnerabilities.

Implement a CSP header in the entry.server.tsx 'handleRequest' function to restrict script execution and style sources.

Verify that the Remix build process is correctly appending hashes to assets and that the server is serving them with long-lived 'immutable' cache headers.

Utilize the 'links' function to preload critical fonts or hero images for specific routes to improve Largest Contentful Paint (LCP).

Run a bundle analyzer (e.g., esbuild-visualizer) to identify and remove large dependencies that are inadvertently included in the client-side bundle.

Ensure images are served in modern formats (WebP/AVIF) and use the 'srcset' attribute for responsive sizing.

Confirm that the hosting provider or the Express/Node server adapter has compression enabled for text-based assets and HTML responses.

Verify that 'remix build' is executed with NODE_ENV set to 'production' to ensure React development checks are disabled.

Create a resource route at /healthcheck that verifies database and cache connectivity for automated load balancer health checks.

If deploying to a serverless environment (e.g., Cloudflare Workers or AWS Lambda), implement a connection pooler like Prisma Accelerate or PgBouncer.

Replace console.log with a structured logging library (e.g., Pino or Winston) in loaders and actions for better observability in production logs.

Integrate Sentry or a similar service within entry.client.tsx and entry.server.tsx to capture runtime exceptions and sourcemaps.

Implement the 'meta' function for every public route to ensure unique titles, descriptions, and Open Graph tags based on loader data.

Ensure every page includes a canonical link tag to prevent duplicate content issues, especially when using query parameters for filtering.

Configure an automated sitemap generation script or resource route that dynamically lists all public-facing URLs.

Add a robots.txt file to the public directory or as a resource route to control crawler access to sensitive paths like /admin or /api.

Inject JSON-LD structured data into the head for product, article, or organization pages to improve search engine rich snippets.