Startup & App Dev Glossary

Every term you need to know — SaaS metrics, product concepts, engineering jargon, and fundraising vocabulary, explained simply.

Product

Engineering

Technical Debt

Technical debt refers to the implied cost of future rework required when shortcuts or suboptimal solutions are chosen during software development for the sake of speed.

API (Application Programming Interface)

An API (Application Programming Interface) is a set of rules and protocols that allows different software applications to communicate with each other — like a contract defining how one piece of software can request data or actions from another.

Row Level Security (RLS)

Row Level Security (RLS) is a PostgreSQL feature that controls which rows in a database table a user can read, insert, update, or delete — enforced at the database level, not the application layer.

Webhook

A webhook is an HTTP callback — a real-time notification sent from one application to another when a specific event occurs, without the receiving application needing to continuously poll for updates.

Sprint

A sprint is a fixed-length, time-boxed development cycle in Agile/Scrum methodology — typically 1 or 2 weeks — during which a defined set of features or tasks are built, tested, and delivered.

Multi-tenancy

Multi-tenancy is an architecture where a single instance of a software application serves multiple customers ('tenants'), with each tenant's data logically isolated from others — sharing the same infrastructure but with strict separation.

React Native

React Native is an open-source framework by Meta that lets developers build native mobile apps for iOS and Android using JavaScript and React — sharing one codebase across both platforms.

Supabase

Supabase is an open-source Backend-as-a-Service (BaaS) that provides a PostgreSQL database, authentication, file storage, real-time subscriptions, and edge functions — positioned as an open-source alternative to Firebase.

Expo

Expo is a framework and platform built on React Native that simplifies mobile app development with managed tooling, cloud builds (EAS), over-the-air updates, and pre-built native modules.

RevenueCat

RevenueCat is a subscription infrastructure platform that abstracts App Store and Google Play billing — handling receipt validation, subscription status, trials, and analytics through a single SDK and API.

No-Code

No-code development uses visual builders and drag-and-drop interfaces to create applications without writing traditional code — platforms include Bubble, Webflow, Adalo, and Glide.