hardSystem Design

How would you design a URL shortener like TinyURL?

Q: How would you design a URL shortener like TinyURL?

## URL shortener — scaling the read path (Key generation uses **base62 of a unique id** — collision-free; see the core design. This answer focuses on the part that actually decides the architecture: serving **billions of redirects** fast and cheap.) Because reads outnumber writes ~100:1 and a redirect must be near-instant, you build **layers of caching** in front of a simple, replicated store: User CDN edge <rect class='d-box-accent' x='194' y='76' width='84' hei

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url-shortener

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Cache-aside redirect lookup

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cache = {}   # Redis in production (code -> url, with a TTL)

def resolve(code, kv):
    if code in cache:               # hot code -> served from memory
        return cache[code]
    url = kv.get(code)              # miss -> fall back to the KV store
    if url:
        cache[code] = url           # populate for next time
    return url

kv = {"abc": "https://example.com/a/very/long/path"}
print(resolve("abc", kv))   # miss -> KV, then cached
print(resolve("abc", kv))   # hit  -> cache

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