HTMX + Rails

The ecosystem-standard authentication gem for Rails: registration, password reset, session management, and confirmable/lockable modules out of the box. The default here because it's what nearly every Rails project reaches for; Rails itself ships with no built-in auth system the way Django does.

A hosted identity platform with an official Ruby SDK for verifying sessions in Rails controllers, worth it over Devise if you'd rather not self-host the auth logic at all, or need enterprise features like SSO that Devise doesn't cover.

A transactional email API for account verification, password resets, and notification emails, sent via Resend's official Ruby SDK from a Rails controller or mailer, with a free tier for getting started.

The established high-volume choice, with dedicated IP addresses and deliverability tooling for apps sending at serious scale. No permanent free plan (a 60-day trial, then paid tiers), so it earns its slot when volume and deliverability matter more than upfront cost.

An all-in-one platform combining the transactional email API with marketing campaigns, a built-in CRM, and SMS from the same dashboard. A permanent free tier of 300 emails a day with no card required makes it an easy starting pick for an early-stage app.

Adds subscription billing, one-time checkout, and invoicing via Stripe's hosted Checkout or embedded Elements, with Rails handling webhook verification and API calls server-side. The stack works fully without it; add this once the product is ready to charge for something.

A utility-class CSS framework: styles are composed directly in markup via class names instead of writing separate stylesheet files. The default styling choice bundled by most modern framework CLIs (create-next-app, create-vue, the SvelteKit and Astro starters all offer it), and the base layer shadcn/ui components are built on when that's loaded into the catalog in the future.

Ready-made components and a grid for ERB views, set up with rails new --css bootstrap or the bootstrap gem, which compiles the Sass source through Rails' CSS bundling. A familiar choice for admin screens and long-lived Rails apps. Pick it or Tailwind, not both.

Alpine.js adds lightweight, declarative client-side interactivity on top of this stack's HTMX-driven Rails views: toggling a mobile menu, showing a modal, or switching an active tab, all without triggering a server round trip HTMX would otherwise need. It is included via a script tag, with behavior written as HTML attributes (x-data, x-show, x-on) rather than a build step, keeping the stack's zero-bundler approach intact.

S3-compatible object storage with no egress fees, so serving uploads, images, and exports costs only for storage and operations. Active Storage has an S3 service in storage.yml that accepts a custom endpoint, and its direct uploads send files from the browser straight to the bucket, with the keys in Rails credentials. The 10 GB free tier covers an early product.

The reference object store and the API the others copy, with the most storage classes, regional controls, and lifecycle rules. Active Storage has an S3 service in storage.yml that accepts a custom endpoint, and its direct uploads send files from the browser straight to the bucket, with the keys in Rails credentials. It fits best when the rest of the app already runs on AWS, though data transfer out is billed.

An S3-compatible store at roughly a third of S3 Standard's storage price, a fit for backups and large media libraries. Active Storage has an S3 service in storage.yml that accepts a custom endpoint, and its direct uploads send files from the browser straight to the bucket, with the keys in Rails credentials. Egress is free up to three times the stored data, and a CDN in front of a public bucket covers heavier delivery.

Rails.cache backed by :redis_cache_store, which makes fragment caching of the partials HTMX swaps in, and Russian-doll caching of nested ones, shared across every Puma process and server. Rails 8 defaults to Solid Cache, which stores the cache in the database, so Redis is the faster choice once cache reads become a load of their own. PostgreSQL already keeps hot rows in memory, so no cache is needed until pages repeat expensive work.

Runs the test suite and triggers deployments on every push, directly from the same GitHub repo the code already lives in, with no separate CI service to configure.

GitLab's built-in CI/CD system, configured via .gitlab-ci.yml in the repository, the natural pick if the project's code lives on GitLab (self-hosted or gitlab.com) rather than GitHub, with the same YAML-pipeline model as GitHub Actions.

Packages the whole Rails + HTMX app into a container image for consistent local development and deployment, independent of the hosting platform chosen above.

Error tracking and performance monitoring with dedicated sentry-ruby and sentry-rails gems, covering both controller errors and background-job failures. Open-source with a self-hosted path, alongside its own managed cloud.

A broader observability platform covering APM, infrastructure metrics, and log management in one dashboard, useful once a team is already running other services worth monitoring alongside this app. Managed-only, with pricing that scales by host and usage rather than Sentry's per-error volume.

An all-in-one product analytics platform: event tracking, session replay, feature flags, and A/B testing in one SDK. The richest feature set if you want more than pageviews.

The industry-standard, free analytics platform, with native Google Ads and Search Console integration. Requires a cookie consent banner in most jurisdictions (GDPR/CCPA), and all data lives on Google's infrastructure, the tradeoff the other three picks were built to avoid.

A lightweight, privacy-first analytics tool with no cookie banner required. A good fit for simple traffic metrics without PostHog's broader feature surface.

Open-source and self-hostable, keeping analytics data on infrastructure you control. Pairs naturally with the self-hosted Hetzner hosting option above if you want to avoid a third-party analytics vendor entirely.