What to work through
Work through a prompt playground as a spoken system design interview. Start by clarifying the scope, sketch a working design and explain the trade-offs behind your choices.
- Pick a model and set its parameters
- Write a system prompt and messages, run them and watch the output stream in
- Save the setup as a preset, then load, update and share it
- Stop a run while it is still streaming
- Compare runs of different setups side by side
Constraints to discuss
- A change to any control answers within 200 milliseconds
- A run can be repeated: the exact setup it used is kept with it
- Unsaved changes are never lost without a warning
- Provider keys never reach the browser
Need a starting point?
Watch for these common gaps as you prepare:
- Each control keeping its own value, so a preset load or a run misses some
- A run that reads the controls while the person is still editing
- Loading a preset without checking it against the chosen model's limits
- Last save wins on a shared preset
- Provider keys sent to the browser
- Waiting to be asked about timeouts, partial outputs and retries
Why this question is in the collection
These sources connect the problem to company interview reports or preparation guides. They do not guarantee what a company will ask you.
- OpenAI: Listed by the Front End Interview Handbook, which mirrors GreatFrontEnd's candidate tips, among OpenAI's frontend system design questions: an internal playground with model choice, editable parameters and presets to save, share and load. The dated tip itself was seen only in a search snippet.
- OpenAI: Listed by PracHub on 2026-04-25 as a frontend engineer technical screen question: a prompt-testing console with model choice, parameters, streamed output and presets, with no candidate narrative.
- Anthropic: Listed by PracHub on 2026-10-05 as a software engineer onsite question on the general loop, not a frontend round: a collaborative prompt playground with versions, runs and comparison, with no candidate narrative.