Design a visual / image search system (search by image, or text-to-image search).

Image search is embedding retrieval at billion-image scale. The tell of a strong answer is knowing when a vision-only encoder suffices and when you need a CLIP-style shared space, plus how the ANN index actually serves the query. Here is the design.

Updated Aug 2026 · Grounded in real Applied AI Engineer interview loops and written to a senior-engineer editorial bar.