Design a rich text editor component
PremiumFrontend systemHard
- Contenteditable
- Document model
- Undo redo
Quick answer
This frontend system interview question asks you to design a rich text editor component. Aim for a design that loads fast, stays responsive and is easy to maintain, then explain components, state, data fetching and trade-offs. Interviewers want to see how you structure the interface, manage state and keep the experience fast.
The problem
Design a rich text editor component, like the editors in Medium or Notion, that other teams embed in comment boxes, blog posts and support tickets. The hard part is behaving the same in Chrome, Safari and Firefox, surviving paste from Word and Google Docs, and making undo feel natural.
It supports bold, italic, underline, headings, bulleted and numbered lists, links, inline code and images.
What must a rich text editor component do?
- Formatting: Toggle marks (bold, italic, underline, code) on a selection or at the caret; set block types (paragraph, heading 1 to 3, list item, blockquote).
- Undo and redo: Ctrl+Z and Ctrl+Shift+Z; continuous typing is grouped into one undo step, while a formatting change is its own step.
How well must it do it?
- Latency: A keystroke appears within 16 ms in a 5,000-word document.
- Safety: Pasted or loaded HTML can never execute scripts or inject styles into the host page.
What scale should you design for?
Use these numbers in your estimates.
The scale numbers unlock with this questionUnlock
Key concepts
- Contenteditable
- Document model
- Undo redo
- Command pattern
- Selection API
- IME composition
How you’ll practise
- Requirements
- Components
- State and data
- Network and caching
- Performance and accessibility
- Wrap-up
Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.
What do interviewers look for?
In any frontend system design round.
- Starts from the user flows and the screens
- Splits the interface into clear components
- Decides where state lives and how it stays in sync
- Plans data fetching, caching and loading states
- Covers performance, accessibility and error states
- Explains how the design holds up on slow networks and small screens
Questions people ask about this interview question
- Which design type is this question?
- It is a frontend system question. You design a rich text editor component and explain your choices the way you would in an interview.
- Is this question asked at entry level?
- It is marked Hard. It suits engineers preparing for senior interviews, where you are expected to drive the discussion and go deep on trade-offs.
- What should I cover first?
- Start with the main user flows, the screens and the data each one needs. Agree on scope with the interviewer before you design anything.
- Can I practise it for free?
- It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.
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Updated · Written by the SevyDevy team