How Trello, Notion, and Other Apps Use Object-Oriented Design to Make Interfaces That Feel Obvious

# Overview Object-oriented design for interfaces treats any user-meaningful thing as an object with visible properties and direct actions. Trello's Cards, Notion's Blocks, and Tinder's Profiles look and behave differently, but they follow the same pattern: give users a stable unit they can recognize, edit, and move. That stability makes complex workflows feel simple.

# What an object is in UI design An object is a thing the interface makes visible and actionable. Each object has two concrete parts: attributes (title, labels, dates, content) and operations (drag, open, edit, like). When those parts are surfaced clearly on the object itself, users learn what the object does by using it instead of reading documentation.

# Trello: Cards as composable work units

# Notion: One universal object that scales Notion standardizes on a single universal object: the Block. Every page element—text, heading, image, to-do, database—is a Block. That uniform foundation makes composition straightforward: different Block types add attributes and operations on top of the same basic rules. A database Block, for example, can be rendered as a table, board, or calendar while remaining the same underlying object. That approach reduces cognitive load as users create and rearrange content.

# How Amazon illustrates object stability across redesigns Amazon's homepage has changed visually many times, but core objects like the Basket, Account, and Search persisted. Those objects survived visual overhauls because they represent the same user-meaningful things across contexts. When the right objects are chosen and kept stable, redesigns can improve aesthetics without breaking the user's mental model.

# Practical steps to apply object-oriented UI design

• Identify the smallest meaningful unit users interact with (task, paragraph, profile). Call it an object.
• Define attributes clearly so what's editable or visible is obvious.
• Attach operations directly to the object's surface (drag handles, action buttons) so actions map to the object.

• Test whether new views reuse existing objects or force users to treat the same thing as different entities.

# Career and product impact Designers who think in objects move beyond producing screens to shaping product structure. Object-first thinking makes interfaces easier to learn, easier to extend, and easier for cross-functional teams to implement. Hiring managers and stakeholders look for designers who can point to a small set of objects that organize a product, because that clarity scales with product complexity.