How dynamic QR codes work.

The technical mechanics, briefly.

The problem

Dynamic QR codes seem magical at first — same printed image, different destinations over time. But the way they actually work is straightforward once you see it. Understanding the mechanics helps you make smart decisions about when to use them and what their failure modes are.

The fix

A dynamic QR encodes a permanent short URL (like qrth.is/r/abc) into the image, instead of your final destination. When someone scans, their phone follows that short URL — which hits our redirect server, which looks up the current destination in a database, which responds with an HTTP 302 redirect to that destination. The phone then loads the destination URL. All in under 200ms.

What you get

  • Step 1: Image encodes a permanent short URL (qrth.is/r/abc). This part is identical to how any static QR works.
  • Step 2: Phone scans and follows the URL. Hits our redirect server, which is just a regular HTTP endpoint.
  • Step 3: Server looks up the current destination in a database (this is what makes it 'dynamic') and returns a 302 redirect.
  • Step 4: Phone follows the redirect to the final destination page. User sees it as a single tap-and-load.

Questions

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Last updated: August 2026

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