Tech stack explained: frontend, backend, APIs, and more

What the user sees and interacts with. The frontend runs in the user's browser — the buttons, forms, layouts, animations, and navigation. Frontend engineers translate designs into interactive interfaces. When something looks wrong or a click does nothing, it is usually a frontend issue.

The server, database, and business logic. Users never see the backend directly — it powers what the frontend displays. When you submit a form, the backend validates the data, writes it to the database, and sends a response back. When something saves incorrectly or a calculation is wrong, that is usually a backend issue.

Can work on both layers. Highly valued at startups and smaller teams because one engineer can ship an entire feature end-to-end. Requires broader knowledge but often means slightly less depth in each area than a dedicated specialist.

Where data is stored permanently. SQL databases (PostgreSQL, MySQL) organize data in tables with rows and columns — think of a structured spreadsheet. NoSQL databases (MongoDB, DynamoDB) store flexible, document-style data in JSON-like formats. Most products use SQL for core data and NoSQL for specific use cases like caching or search.

Servers rented from a cloud provider instead of physically owned. AWS (Amazon), Google Cloud, and Azure (Microsoft) are the three dominant providers. Instead of buying a server and putting it in a data center, you pay for compute power by the hour. This is why startups can scale without huge upfront infrastructure costs.

Deployment is the act of releasing new or updated code to the live environment that real users interact with. When an engineer says 'I deployed this morning,' they mean they pushed a code change to production. A failed deployment means something broke when code went live.

Automated pipelines that test and release code without manual steps. When a developer pushes code, CI runs automated tests to check nothing is broken. If tests pass, CD automatically deploys the change. This is why modern teams can ship multiple times per day safely.

Instead of one large application, the product is split into small, independent services that communicate via APIs. The payments service, the notifications service, and the user service all run separately. This means one service can be updated or fail without taking down the entire product.

A repository is the folder structure that contains all the code for a project, tracked with a version control system (almost always Git). GitHub, GitLab, and Bitbucket are platforms that host repos. When engineers say 'open a PR' (pull request), they mean proposing changes to the code in the repo.

Code runs in different environments at different stages. Dev is the local environment where engineers build. Staging is a copy of production used for testing before release. Production is the live site that real users see. A bug in staging is a near miss; a bug in production affects your users.

Fast to build, scales well, large talent pool. Most B2B SaaS products launched after 2015 follow a similar pattern.

Mature, audited, integrates with legacy systems. Common in finance, healthcare, and government. Slower to change.

Shopify for speed; custom builds for complex catalogs or unique checkout flows. Stripe is the default payments layer.

Python to move and transform data, dbt to model it, Snowflake to store it, Looker to visualize it. This is the modern analytics stack.