Express + MongoDB

A transactional email API for account verification, password resets, and notification emails, sent via Resend's official Node.js SDK from an Express route handler, 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 Express 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.

S3-compatible object storage with no egress fees, so serving uploads, images, and exports costs only for storage and operations. An Express route signs a presigned URL with @aws-sdk/client-s3 and the s3-request-presigner package so the browser uploads straight to the bucket, and the keys stay in server environment variables. 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. An Express route signs a presigned URL with @aws-sdk/client-s3 and the s3-request-presigner package so the browser uploads straight to the bucket, and the keys stay in server environment variables. 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. An Express route signs a presigned URL with @aws-sdk/client-s3 and the s3-request-presigner package so the browser uploads straight to the bucket, and the keys stay in server environment variables. Egress is free up to three times the stored data, and a CDN in front of a public bucket covers heavier delivery.

Caches expensive MongoDB aggregations and third-party API responses, so repeat requests return from memory instead of rerunning the query. Express reaches it through ioredis, a small cache-aside helper stores each result with an expiry, and a Redis-backed rate limiter protects public endpoints across every API instance. It is worth adding when response times or database load start to grow under real traffic, rather than on day one.

Background work for an Express API, such as webhook delivery, bulk imports, or third-party syncs, needs somewhere durable to wait. BullMQ queues it in Redis and runs it in worker processes with typed job data, retries with exponential backoff, rate limits for upstream APIs, and cron-style job schedulers. Express itself offers nothing beyond a promise that dies with the process. Redis comes with BullMQ, and the instance used for caching can carry the queues as well.

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 Express API into a container image for consistent local development and deployment, independent of the hosting platform chosen above.

Error tracking and performance monitoring with Sentry's Node SDK, wired into Express middleware. 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 API. Managed-only, with pricing that scales by host and usage rather than Sentry's per-error volume.